1.
Symphony Hall, Birmingham
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Symphony Hall is a 2,262 seat concert venue in Birmingham, England. It was officially opened by the Queen in June 1991, although had been opened on April 15,1991 and it is home to the City of Birmingham Symphony Orchestra and hosts around 270 events a year. It was completed at a cost of £30 million, the halls interior is modelled upon the Musikverein in Vienna and the Concertgebouw in Amsterdam. A particularly innovative feature is the halls acoustic flexibility and it has a reverberation chamber behind the stage and extending high along the sides, adding 50% to the halls volume, the doors to which can be remotely opened or closed. The U-shaped reverberation chamber area has a volume of 12,700 cubic metres, there is an acoustic canopy which can be raised or lowered above the stage. Dampening panels can be extended or retracted to ensure that the sound of the space is perfectly matched to the scale and style of the music to be performed, there are also reverse fan walls at the rear of the hall which provide further reflections of sound. All the walls and the ceiling are 200 millimetres thick and are made of concrete, the hall is built only 30 metres from a covered railway line. To prevent the transmission of vibrations, the hall is mounted on rubber cushions, the hall is also shielded from heavy traffic on Broad Street by double skins of concrete. Large, low-speed air ducting cuts the ventilation noise, in 2001, a 6000-pipe symphony organ was installed, designed and built by Johannes Klais Orgelbau in Bonn and specially tailored to the halls reverberation chambers. This is now the largest mechanical organ in the UK. List of concert halls Official website Klais pipe organ
2.
Acoustical engineering
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Acoustical engineering is the branch of engineering dealing with sound and vibration. It is the application of acoustics, the science of sound and vibration, Acoustical engineers are typically concerned with the design, analysis and control of sound. One goal of engineering can be the reduction of unwanted noise. Unwanted noise can have significant impacts on animal and human health and well-being, reduce attainment by pupils in schools, acoustic engineers usually possess a bachelors degree or higher qualification in acoustics, physics or another engineering discipline. Practicing as an acoustic engineer usually requires a degree with significant scientific. Acoustic engineers might work in consultancy, specializing in particular fields, such as architectural acoustics. Acousticians are also involved in researching and understanding sound scientifically, some positions, such as faculty require a Doctor of Philosophy. In most countries, a degree in acoustics can represent the first step towards professional certification, after completing a certified degree program the engineer must satisfy a range of requirements before being certified. Once certified, the engineer is designated the title of Chartered Engineer, the listed subdisciplines are loosely based on the PACS coding used by the Acoustical Society of America. Aeroacoustics is concerned with how noise is generated by the movement of air, for instance via turbulence, aeroacoustics plays an important role in understanding how noise is generated by aircraft and wind turbines, as well as exploring how wind musical instruments work. Audio signal processing is the manipulation of audio signals using analog. Perceptual coding in MP3 and Opus, and to understand the content of the signal, audio engineers develop and use audio signal processing algorithms. Architectural acoustics is the science and engineering of achieving a good sound within a building, architectural acoustic design is usually done by acoustic consultants. Bioacoustics usually concerns the study of sound production and hearing in animals. This branch of acoustic engineering deals with the design of headphones, microphones, loudspeakers, sound systems, sound reproduction, environmental acoustics work is usually done by acoustic consultants or those working in environmental health. Recent research work has put an emphasis on soundscapes, the positive use of sound. Musical acoustics is concerned with researching and describing the physics of music, noise control is a set of strategies to reduce noise pollution by reducing noise at its source, by inhibiting sound propagation using noise barriers or similar, or by the use of ear protection. Control at the source is the most cost-effective way of providing noise control, noise control engineering applied to cars and trucks is known as noise, vibration, and harshness
3.
Wallace Clement Sabine
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Wallace Clement Sabine was an American physicist who founded the field of architectural acoustics. He graduated from Ohio State University in 1886 at the age of 18 before joining Harvard University for graduate study, Sabine was architectural acoustician of Bostons Symphony Hall, widely considered one of the two or three best concert halls in the world for its acoustics. Sabines career is the story of the birth of the field of architectural acoustics. In 1895, acoustically improving the Fogg Lecture Hall, part of the recently constructed Fogg Art Museum, was considered a task by the senior staff of the physics department at Harvard. The assignment was passed down until it landed on the shoulders of a physics professor. Although considered a popular lecturer by the students, Sabine had never received his Ph. D. Sabine tackled the problem by trying to determine what made the Fogg Lecture Hall different from other, acoustically acceptable facilities. In particular, the Sanders Theater was considered acoustically excellent, for the next several years, Sabine and a group of assistants spent each night moving materials between the two lecture halls and testing the acoustics. On some nights they would borrow hundreds of seat cushions from the Sanders Theater, once the measurements were taken and before morning arrived, everything was quickly replaced in both lecture halls, in order to be ready for classes the next day. His formula, if all units are SI, is T = V A ⋅0.25 seconds, while optimal lecture hall acoustics featured reverberation times of slightly under 1 second. Regarding the Fogg Museum lecture room, Sabine noted that a word remained audible for about 5.5 seconds. Listeners thus contended with a high degree of resonance and echo. Using what he discovered, Sabine deployed sound absorbing materials throughout the Fogg Lecture Hall to cut its reverberation time and reduce the echo effect. This accomplishment cemented Wallace Sabines career, and led to his hiring as the consultant for Bostons Symphony Hall. His acoustic design was successful and Symphony Hall is generally considered one of the best symphony halls in the world, the unit of sound absorption, the sabin, was named in his honor. F. Sanders Theatre Wallace Clement Sabine at the Mathematics Genealogy Project
4.
Harvard Art Museums
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The Harvard Art Museums are part of Harvard University and comprise three museums, the Fogg Museum, the Busch-Reisinger Museum, and the Arthur M. The three museums that constitute the Harvard Art Museums were initially integrated into an institution under the name Harvard University Art Museums in 1983. The word University was dropped from the name in 2008. In 2008, the Harvard Art Museums historic building at 32 Quincy Street, in a view of the front facade, the glass roof and other expansions are mostly concealed, largely preserving the original appearance of the building. The renovation adds six levels of galleries, classrooms, lecture halls, the new building was opened in November 2014. The museum was housed in an Italian Renaissance-style building designed by Richard Morris Hunt. In 1925, the building was replaced by a Georgian Revival-style structure on Quincy Street, designed by Coolidge, Shepley, Bulfinch, and Abbott. The Fogg Museum is renowned for its holdings of Western paintings, sculpture, decorative arts, photographs, prints, particular strengths include Italian Renaissance, British Pre-Raphaelite, and French art of the 19th century, as well as 19th- and 20th-century American paintings and drawings. Central to the Foggs holdings is the Grenville L. Winthrop Collection, flemish Renaissance paintings — Master of Catholic Kings, Jan Provoost, Master of Holy Blood, Aelbert Bouts, and Master of Saint Ursula. Italian Renaissance period paintings — Fra Angelico, Sandro Botticelli, Domenico Ghirlandaio, Gherardo Starnina, Cosme Tura, Giovanni di Paolo, French Baroque period paintings — Nicolas Poussin, Jacques Stella, Nicolas Regnier, and Philippe de Champaigne. Dutch Master paintings — Rembrandt, Emanuel de Witte, Jan Steen, Willem Van de Velde, Jacob Van Ruisdael, Salomon van Ruysdael, Jan van der Heyden, william James spoke at its dedication. Its holdings include significant works of Austrian Secession art, German expressionism, 1920s abstraction, other strengths include late medieval sculpture and 18th-century art. It has sculpture by Alfred Barye, Kathe Kollwitz, George Minne, from 1921 to 1991, the Busch-Reisinger was located in Adolphus Busch Hall at 29 Kirkland Street. In 1991, the Busch-Reisinger moved to the new Werner Otto Hall, designed by Gwathmey Siegel & Associates, kuno Francke, 1903-1930 Charles L. Kuhn, 1930-1968 Peter Nisbet Lynette Roth The Arthur M. Sackler Museum opened in 1985. The museum building, which was designed by British architect James Stirling, was named for the donor, Arthur M. Sackler, a psychiatrist, entrepreneur. The museum also housed offices for the History of Art and Architecture faculty, as of 2016, the old Sackler Museum building houses the History of Art and Architecture Department and the Media Slide Library. The ancient Mediterranean and Byzantine collections comprise significant works in all media from Greece, Rome, Egypt, strengths include Greek vases, small bronzes, and coins from throughout the ancient Mediterranean world. The building is remarkable for the creative virtuosity with which its functions are accommodated while suggesting a monumentality that belies actual dimensions, Stirling was lucky to have as a client the director of the Fogg, Seymour Slive, who understood this achievement immediately
5.
Symphony Hall, Boston
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Symphony Hall is a concert hall located at 301 Massachusetts Avenue in Boston, Massachusetts. Designed by McKim, Mead and White, it was built in 1900 for the Boston Symphony Orchestra, the hall was designated a U. S. National Historic Landmark in 1999 and is a pending Boston Landmark. It was then noted that Symphony Hall remains, acoustically, among the top three concert halls in the world, and is considered the finest in the United States. Symphony Hall was inaugurated on October 15,1900, after the Orchestras original home was threatened by road-building, admired for its lively acoustics from the time of its opening, the hall is often cited as one of the best sounding classical concert venues in the world. The hall is modeled on the second Gewandhaus concert hall in Leipzig, the Hall is relatively long, narrow, and high, in a rectangular shoebox shape like Amsterdams Concertgebouw and Viennas Musikverein. It is 18. 6m high,22. 9m wide, stage walls slope inward to help focus the sound. With the exception of its floors, the Hall is built of brick, steel. Side balconies are very shallow to avoid trapping or muffling sound, conductor Herbert von Karajan, in comparing it to the Musikverein, stated that for much music, it is even better. Because of its slightly lower reverberation time, in 2006, due to years of wear and tear, the original concert stage floor was replaced at a cost of $250,000. In order to any change to the sound of the hall. These included tongue-in-groove, three-quarter inch, hard maple boards, a compressed wool underlayment and hardened steel cut nails, the vertical grain fir subfloor from 1899 was in excellent shape and was left in place. The nails used in the new floor were hand cut using the size and construction as the originals. Beethovens name is inscribed over the stage, the musicians name that appears in the hall since the original directors could agree on no other name. The halls leather seats are the ones installed in 1900. The hall seats 2,625 people during Symphony season and 2,371 during the Pops season, sixteen replicas of Greek and Roman statues line the upper level of the halls walls. Ten are of subjects, and six of historical figures. All are of plaster cast by P. P. Caproni, the Symphony Hall organ, a 4, 800-pipe Aeolian-Skinner was designed by G. Donald Harrison, installed in 1949, and autographed by Albert Schweitzer. It replaced the halls first organ, built in 1900 by George S. Hutchings of Boston, the Hutchings organ had fallen out of fashion by the 1940s when lighter, clearer tones became preferred
6.
Roof
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A roof is part of a building envelope. It is the covering on the uppermost part of a building or shelter which provides protection from animals and weather, notably rain or snow, the word also denotes the framing or structure which supports that covering. In most countries a roof protects primarily against rain, a verandah may be roofed with material that protects against sunlight but admits the other elements. The roof of a garden conservatory protects plants from cold, wind, and rain, a roof may also provide additional living space, for example a roof garden. Old English hrof roof, ceiling, top, summit, heaven, sky, also figuratively, highest point of something, there are no apparent connections outside the Germanic family. English alone has retained the word in a sense, for which the other languages use forms corresponding to OE. In many parts of the ceramic tiles have been the predominant roofing material for centuries. Other roofing materials include asphalt, coal tar pitch, EPDM rubber, Hypalon, polyurethane foam, PVC, slate, Teflon fabric, TPO, and wood shakes and shingles. The construction of a roof is determined by its method of support and how the space is bridged. The pitch is the angle at which the roof rises from its lowest to highest point, most US domestic architecture, except in very dry regions, has roofs that are sloped, or pitched. Although modern construction such as drainpipes may remove the need for pitch, roofs are pitched for reasons of tradition. So the pitch is dependent upon stylistic factors, and partially to do with practicalities. Some types of roofing, for example thatch, require a steep pitch in order to be waterproof, other types of roofing, for example pantiles, are unstable on a steeply pitched roof but provide excellent weather protection at a relatively low angle. In regions where there is rain, an almost flat roof with a slight run-off provides adequate protection against an occasional downpour. Drainpipes also remove the need for a sloping roof, a person that specializes in roof construction is called a roofer. The shape of roofs differs greatly from region to region, the main factors which influence the shape of roofs are the climate and the materials available for roof structure and the outer covering. The basic shapes of roofs are flat, mono-pitched, gabled, hipped, butterfly, there are many variations on these types. Roofs constructed of sections that are sloped are referred to as pitched roofs
7.
Eaves
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The eaves are the edges of the roof which overhang the face of a wall and, normally, project beyond the side of a building. The eaves form an overhang to throw water clear of the walls and may be decorated as part of an architectural style. Eaves is derived from Old English efes meaning edge, according to the Oxford English Dictionary, eaves is both the singular and plural form of the word. However, the Merriam-Webster website lists the word as eave and states that it is used in plural. The word was used before the 12th century in the form efes, the primary function of the eaves is to keep rain water off the walls and to prevent the ingress of water at the junction where the roof meets the wall. The eaves may also protect a pathway around the building from the rain, prevent erosion of the footings, the eaves overhang may also shelter openings to ventilate the roof space. Aesthetic, traditional or purely decorative considerations may prevail over the functional requirements of the eaves. At the gables the eaves may extend beyond the end wall by projecting the purlins and are usually capped off by bargeboards to protect the wall. Eaves must be designed for wind speeds as the overhang can significantly increase the wind loading on the roof. Chhajja Eavesdrip Eavesdropping Gargoyle Lookout Rainhead Soffit Media related to Eaves at Wikimedia Commons
8.
Wall
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A wall is a structure that defines an area, carries a load, or provides shelter or security. an earthen wall or rampart set with palisades, a row or line of stakes, a wall, a rampart, fortification. While the Latin word murus means a stone wall. English uses the word to mean an external wall and the internal sides of a room. Many languages distinguish between the two, in German, some of this distinction can be seen between Wand and Mauer, in Spanish between pared and muro. The word wall originally referred to defensive walls and ramparts, building walls purposes are to support roofs, floors and ceilings, enclose a space as part of the building envelope, along with a roof to give buildings form, and to provide shelter and security. In addition, the wall may house various types of such as electrical wiring or plumbing. Wall construction falls into two categories, framed walls or mass-walls. In framed walls the load is transferred to the foundation through posts, framed walls most often have three or more separate components, the structural elements, insulation, and finish elements or surfaces. There are three basic methods walls control water intrusion, moisture storage, drained cladding, or face-sealed cladding, moisture storage is typical of stone and brick mass-wall buildings where moisture is absorbed and released by the walls of the structure itself. Sometimes ventilation is provided in addition to the plane such as in rainscreen construction. Face-sealed also called barrier wall or perfect barrier cladding relies on maintaining a leak-free surface of the cladding, examples of face sealed cladding are the early exterior insulation finishing systems, structural glazing, metal clad panels, and corrugated metal. In architecture and civil engineering, curtain wall refers to a facade that is not load-bearing but provides decoration, finish, front, face. Mullion walls are a system that carries the load of the floor slab on prefabricated panels around the perimeter. A partition wall is a wall that separates rooms, or divides a room, partition walls are usually not load-bearing. Partition walls are constructed of materials, including steel panels, bricks, blocks of clay, terra-cotta, concrete. Some partition walls are made of sheet glass, glass partition walls are a series of individual toughened glass panels mounted in wood or metal framing. They may be suspended from or slide along a robust aluminium ceiling track, the system does not require the use of a floor guide, which allows easy operation and an uninterrupted threshold. A timber partition consists of a framework, supported on the floor or by side walls
9.
Window
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A window is an opening in a wall, door, roof or vehicle that allows the passage of light and, if not closed or sealed, air and sound by using sheet glass. Modern windows are glazed or covered in some other transparent or translucent material. Windows are held in place by frames, many glazed windows may be opened, to allow ventilation, or closed, to exclude inclement weather. Windows often have a latch or similar mechanism to lock the window shut, the Romans were the first known to use glass for windows, a technology likely first produced in Roman Egypt, in Alexandria ca.100 AD. Paper windows were economical and widely used in ancient China, Korea, in England, glass became common in the windows of ordinary homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century. In the 19th century American west, greased paper windows came to be used by itinerant groups, modern-style floor-to-ceiling windows became possible only after the industrial plate glass making processes were perfected. The English language-word window originates from the Old Norse vindauga, from vindr – wind and auga – eye, the Danish word is pronounced fairly similarly to window. Window is first recorded in the early 13th century, and originally referred to a hole in a roof. Window replaced the Old English eagþyrl, which literally means eye-hole, many Germanic languages however adopted the Latin word fenestra to describe a window with glass, such as standard Swedish fönster, or German Fenster. The use of window in English is probably because of the Scandinavian influence on the English language by means of loanwords during the Viking Age, in English the word fenester was used as a parallel until the mid-18th century. Fenestration is still used to describe the arrangement of windows within a façade, as well as defenestration, in the 13th century, the earliest windows were unglazed openings cut in a roof to admit light during the day. Later, windows were covered with animal hide, cloth, or wood, shutters that could be opened and closed came next. Over time, windows were built that both protected the inhabitants from the elements and transmitted light, using small pieces of translucent material set in frameworks of wood. In the Far East, paper was used to fill windows, the Romans were the first known to use glass for windows, a technology likely first produced in Roman Egypt. It would be over a millennium before a window glass became transparent enough to see through clearly, over the centuries techniques were developed to shear through one side of a blown glass cylinder and produce thinner rectangular window panes from the same amount of glass material. This gave rise to tall narrow windows, usually separated by a vertical support called a mullion, mullioned glass windows were the windows of choice among European well-to-do, whereas paper windows were economical and widely used in ancient China, Korea and Japan. In England, glass became common in the windows of homes only in the early 17th century whereas windows made up of panes of flattened animal horn were used as early as the 14th century. Modern-style floor-to-ceiling windows became possible only after the plate glass making processes were perfected
10.
Door
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A door is a moving structure used to block off, and allow access to, an entrance to or within an enclosed space, such as a building or vehicle. Doors normally consist of a panel that swings on hinges on the edge, similar exterior structures to doors are called gates. Typically, doors have a side that faces the inside of a space. In many cases the interior side of a door mostly matches its exterior side, when open, doors admit people, animals, ventilation or light. The door is used to control the atmosphere within a space by enclosing the air drafts. Doors are significant in preventing the spread of fire and they also act as a barrier to noise. Many doors are equipped with locking mechanisms to allow entrance to certain people, as a form of courtesy and civility, people often knock before opening a door and entering a room. Doors are used to screen areas of a building for aesthetics, keeping formal, Doors also have an aesthetic role in creating an impression of what lies beyond. Doors are often endowed with ritual purposes, and the guarding or receiving of the keys to a door, or being granted access to a door can have special significance. Similarly, doors and doorways frequently appear in metaphorical or allegorical situations, literature, the earliest in records are those represented in the paintings of the Egyptian tombs, in which they are shown as single or double doors, each in a single piece of wood. Doors were once believed to be the doorway to the afterlife. The stiles were the boards, one of which, tenoned or hinged, is known as the hanging stile. The horizontal cross pieces are the top rail, bottom rail, the most ancient doors were made timber, such as those referred to in the Biblical depiction of King Solomons temple being in olive wood, which were carved and overlaid with gold. The doors dwelt upon in Homer would appear to have been cased in silver or brass, besides olive wood, elm, cedar, oak and cypress were used. A5, 000-year-old door has been found by archaeologists in Switzerland. All ancient doors were hung by pivots at the top and bottom of the hanging stile which worked in sockets in the lintel and sill and those found at Nippur by Dr. Hilprecht dating from 2000 B. C. were in dolerite. The tenons of the gates at Balawat were sheathed with bronze and these doors or gates were hung in two leaves, each about 8 ft 4 in wide and 27 ft. high, they were encased with bronze bands or strips,10 in. High, covered with decoration of figures, etc
11.
Ceiling
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A ceiling /ˈsiːlɪŋ/ is an overhead interior surface that covers the upper limits of a room. It is not generally considered an element, but a finished surface concealing the underside of the roof structure or the floor of a storey above. Ceilings can be decorated to taste, and there are fine examples of frescoes. The most common type of ceiling is the ceiling which is suspended from structural elements above. Pipework or ducts can be run in the gap above the ceiling, other types of ceiling include the cathedral ceiling, the concave or barrel-shaped ceiling, the stretched ceiling and the coffered ceiling. Coving often links the ceiling to the surrounding walls, ceilings can play a part in reducing fire hazard, and a system is available for rating the fire resistance of dropped ceilings. Ceilings are classified according to their appearance or construction, a cathedral ceiling is any tall ceiling area similar to those in a church. A dropped ceiling is one in which the surface is constructed anywhere from a few inches or centimetres to several feet or a few metres below the structure above it. This may be done for aesthetic purposes, such as achieving a desirable ceiling height, an inverse of this would be a raised floor. A cove ceiling uses a curved plaster transition between wall and ceiling, it is named for cove molding, a molding with a concave curve, a stretched ceiling uses a number of individual panels using material such as PVC fixed to a permieter rail. Ceilings have frequently been decorated with painting, mosaic tiles. While hard to execute a decorated ceiling has the advantage that it is protected from damage by fingers. In the past, however, this was more than compensated for by the damage from smoke from candles or a fireplace, many historic buildings have celebrated ceilings. Perhaps the most famous is the Sistine Chapel ceiling by Michelangelo, ceiling height may have psychological impacts. The most common ceiling that contributes to fire-resistance ratings in commercial and residential construction is the dropped ceiling, an independent ceiling, however, can be constructed such that it has a stand-alone fire-resistance rating. Such systems must be tested without the benefit of being suspended from a slab above in order to prove that the system is capable of holding itself up. This type of ceiling would be installed to protect items above from fire, merriam-Webster ceiling definition Diydata. com treatise on lath & plasterboard ceilings Virtualmuseum. ca treatise on ceiling construction
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Dropped ceiling
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A dropped ceiling is a secondary ceiling, hung below the main ceiling. Dropped ceilings and ceiling tiles were being used in Japan for aesthetic reasons as early as the Muromachi Period, blackfriars Theater in London, England, built in 1596, had dropped ceilings to aid acoustics. U. S. Patent No.1,470,728 for modern dropped ceilings was applied for by E. E. Hall on May 28,1919, once the repair or inspection was completed, the tiles had to be reinstalled. This process could be very time-consuming and expensive, on September 8,1958 Donald A. Brown of Westlake, Ohio filed for a patent for Accessible Suspended Ceiling Construction. This invention provided suspended ceiling construction in which access may readily be obtained at any desired location, Patent Number US2,984,946 A was granted on May 23,1961. Brown has sometimes credited as being the inventor of the dropped ceiling even though other patents preceded his as shown in the table below. Drop ceilings may also be used to hide problems, such as structural damage, further, drop out ceilings can also conceal the sprinkler systems while still providing full fire suppression functionality. Custom runs of specialty ceiling tiles can be done at low cost compared with the past. Acoustic balance and control was another early objective of dropped ceilings, a noisy room can overstimulate occupants, while a too quiet interior may seem dull and uninviting. The acoustic performance of suspended ceilings has improved dramatically over the years and this is sometimes achieved by adding insulation known as Sound Attenuation Batts, more commonly referred to as sound batts, above the panels to help deaden sounds and keep adjacent rooms quieter. Many manufacturers of modern dropped ceilings include sustainability as an objective, sustainable features may include, Energy efficiency, including daylight efficacy and thermal insulating qualities. This uses the plane to reflect daylight as well as electrical illumination to maximize lumen efficacy. A common measure of the reflectance of a ceiling material is ASTM E1477 for Light Reflectance. A level of about 75% is considered good, although levels are possible. Fortunately, most ceiling system products are now designed with this integration in mind, decisions here can also affect aesthetics as well as access and maintenance. These channels snap together in a regularly spaced pattern of cells, each cell is then filled with lightweight ceiling tiles or panels which simply drop into the grid. The primary grid types are Standard 1, Slimline, and concealed grid, in the United States the cell size in the suspension grids is typically either 2 ft ×2 ft or 2 ft ×4 ft and the ceiling tiles are the same size. In Europe the cell size in the grids is 600×600 mm
13.
Duct (flow)
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Ducts are conduits or passages used in heating, ventilation, and air conditioning to deliver and remove air. The needed airflows include, for example, supply air, return air, as such, air ducts are one method of ensuring acceptable indoor air quality as well as thermal comfort. A duct system is also called ductwork, planning, sizing, optimizing, detailing, and finding the pressure losses through a duct system is called duct design. For insulation purposes, metal ducts are lined with faced fiberglass blankets or wrapped externally with fiberglass blankets. When called for, a double walled duct is used and this will usually have an inner perforated liner, then a 1–2 layer of fiberglass insulation contained inside an outer solid pipe. Rectangular ductwork commonly is fabricated to suit by specialized metal shops, for ease of handling, it most often comes in 4 sections. Stock pipe is sold in 10 joints. There are also 5 joints of non-spiral type pipe available, which is used in residential applications. Aluminium ductwork is lightweight and quick to install, also, custom or special shapes of ducts can be easily fabricated in the shop or on site. The ductwork construction starts with the tracing of the duct outline onto the aluminium preinsulated panel, the parts are then typically cut at 45°, bent if required to obtain the different fittings and finally assembled with glue. Aluminium tape is applied to all seams where the surface of the aluminium foil has been cut. A variety of flanges are available to suit various installation requirements, all internal joints are sealed with sealant. Aluminum is also used to make round spiral duct, but it is less common than galvanized steel. Traditionally, air ductwork is made of metal which was installed first. Today, a metal fabrication shop would commonly fabricate the galvanized steel duct. However, ductwork manufactured from rigid insulation panels does not need any further insulation, both polyurethane and phenolic foam panels are manufactured with factory applied aluminium facings on both sides. The thickness of the foil can vary from 25 micrometres for indoor use to 200 micrometres for external use or for higher mechanical characteristics. Most manufacturers of rigid polyurethane or phenolic foam panels use pentane as foaming agent instead of the aforementioned gasses, a rigid phenolic insulation ductwork system is listed as a class 1 air duct to UL181 Standard for Safety
14.
Acoustic transmission
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Acoustic transmission is the transmission of sounds through and between materials, including air, wall, and musical instruments. The degree to which sound is transferred between two materials depends on how well their acoustical impedances match, musical instruments are generally designed to radiate sound effectively. A high-impedance part of the instrument, such as a string, the soundboard then moves the still lower-impedance air. Without bridge and soundboard, the instrument does not transmit sound to the air. An electric guitar has no soundboard, it uses a microphone pick-up, without amplification, electric guitars are very quiet. Stethoscopes roughly match the impedance of the human body, so they transmit sounds from a patients chest to the doctors ear much more effectively than the air does. Putting an ear to someones chest would have a similar effect, acoustic transmission in building design refers to a number of processes by which sound can be transferred from one part of a building to another. Structural isolation therefore becomes an important consideration in the design of buildings. Highly sensitive areas of buildings, for recording studios, may be almost entirely isolated from the rest of a structure by constructing the studios as effective boxes supported by springs. Air tightness also becomes an important control technique, a tightly sealed door might have reasonable sound reduction properties, but if it is left open only a few millimeters its effectiveness is reduced to practically nothing. The most important acoustic control method is adding mass into the structure, such as a dividing wall. Impact transmission - a noise source in one room results from an impact of an object onto a surface, such as a floor. A typical example would be the sound of footsteps in a room being heard in a room below, acoustic control measures usually include attempts to isolate the source of the impact, or cushioning it. For example carpets will perform better than hard floors. For example, in a framed building, once the frame itself is set into motion the effective transmission can be pronounced. Handbook of building technology, acoustics and daylighting
15.
Party wall
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A party wall is a dividing partition between two adjoining buildings that is shared by the tenants of each residence or business. When built for purpose, the builder will lay the wall along a property line dividing two terraced flats or row houses, so that one half of the walls thickness lies on each property. This type of wall is usually structural, Party walls can also be formed by two abutting walls built at different times. The term can be used to describe a division between separate units within a multi-unit apartment complex. Very often the wall in case is non-structural but designed to meet established criteria for sound and/or fire protection between residential units. Party walls are made of non-combustible material. Where required by code, the party wall could be a firewall, the wall starts at the foundation and continues up to a parapet, creating two separate and structurally independent buildings on either side. In cases where the ownership is not shared, both parties have use of the wall, if not ownership, other party structures can exist, such as floors dividing flats or apartments. Apart from special statutory definitions, the term Party Wall may be used in four different legal senses, for this reason, expert surveyors are used in the main to issue notices, deal with the response from someone receiving a notice and settling any dispute by an Award. Details can be obtained from the Royal Institution of Chartered Surveyors, originating in London as early as the 11th century, requirements for terraced houses to have a dividing wall substantially capable of acting as a fire break have been applied in some form or other. Evidently, this was not enough to prevent the great fires of London. In England and Wales, the Party Wall etc, act 1996, to afford rights on the owners of party walls, other party structures, and other matters affecting adjoining structures. Nothing can be done to the party wall without legal consent of both neighboring parties, repairs to the wall are split equally between the two neighboring parties. No beams can be placed in the walls by either party more than a one-half inch the thickness of the wall. If a party does wish to install beams into the greater than one-half inch thickness of the wall then materials such as jams. Rights and obligations are governed by statutes, and common law. Party wall guidance Royal Institution of Chartered Surveyors Paris Party Wall The Law and Practice of Party Walls – The most recent and comprehensive text on party wall issues
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Apartment
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An apartment or a flat is a self-contained housing unit that occupies only part of a building, correctly, on a single level without a stair. In Scotland it is called a block of flats or, if its a traditional building, a tenement. Apartments may be owned by an owner/occupier, by leasehold tenure or rented by tenants, the term apartment is favoured in North America. In the UK, the apartment is more usual in professional real estate and architectural circles where otherwise the term flat is commonly. Technically multi-storey apartments are referred to as duplex indicating the number of floors within the property, usage generally follows the British in Ireland, Singapore, Hong Kong and most Commonwealth nations. In Malaysian English, flat often denotes a housing block of lesser quality meant for lower-income groups, while apartment is more generic, in Australian English, the term flat is traditionally used, but the term unit is frequently used. More recently, the apartment is being used. Tenement law refers to the basis of permanent property such as land or rents. It may be combined as in Messuage or Tenement to encompass all the land, buildings. Most apartments are in buildings designed for the purpose, but large older houses are divided into apartments. The word apartment denotes a unit or section in a building. In some locations, particularly the United States, the word connotes a rental unit owned by the building owner, in the England and Wales, some flat owners own shares in the company that owns the freehold of the building as well as holding the flat under a lease. This is commonly known as a share of freehold flat, the freehold company has the right to collect annual ground rents from each of the flat owners in the building. The freeholder can also develop or sell the building, subject to the usual planning and this does not happen in Scotland, where long leasehold of residential property was formerly unusual, and is now not possible. In some countries the word unit is a general term referring to both apartments and rental business suites. The word unit is used only in the context of a specific building. This building has three units or Im going to rent a unit in this building, but not Im going to rent a unit somewhere, in Australia, a unit refers to flats, apartments or even semi-detached houses. An industrial, warehouse, or commercial space converted to an apartment is called a loft
17.
Science
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Science is a systematic enterprise that builds and organizes knowledge in the form of testable explanations and predictions about the universe. The formal sciences are often excluded as they do not depend on empirical observations, disciplines which use science, like engineering and medicine, may also be considered to be applied sciences. However, during the Islamic Golden Age foundations for the method were laid by Ibn al-Haytham in his Book of Optics. In the 17th and 18th centuries, scientists increasingly sought to formulate knowledge in terms of physical laws, over the course of the 19th century, the word science became increasingly associated with the scientific method itself as a disciplined way to study the natural world. It was during this time that scientific disciplines such as biology, chemistry, Science in a broad sense existed before the modern era and in many historical civilizations. Modern science is distinct in its approach and successful in its results, Science in its original sense was a word for a type of knowledge rather than a specialized word for the pursuit of such knowledge. In particular, it was the type of knowledge which people can communicate to each other, for example, knowledge about the working of natural things was gathered long before recorded history and led to the development of complex abstract thought. This is shown by the construction of calendars, techniques for making poisonous plants edible. For this reason, it is claimed these men were the first philosophers in the strict sense and they were mainly speculators or theorists, particularly interested in astronomy. In contrast, trying to use knowledge of nature to imitate nature was seen by scientists as a more appropriate interest for lower class artisans. A clear-cut distinction between formal and empirical science was made by the pre-Socratic philosopher Parmenides, although his work Peri Physeos is a poem, it may be viewed as an epistemological essay on method in natural science. Parmenides ἐὸν may refer to a system or calculus which can describe nature more precisely than natural languages. Physis may be identical to ἐὸν and he criticized the older type of study of physics as too purely speculative and lacking in self-criticism. He was particularly concerned that some of the early physicists treated nature as if it could be assumed that it had no intelligent order, explaining things merely in terms of motion and matter. The study of things had been the realm of mythology and tradition, however. Aristotle later created a less controversial systematic programme of Socratic philosophy which was teleological and he rejected many of the conclusions of earlier scientists. For example, in his physics, the sun goes around the earth, each thing has a formal cause and final cause and a role in the rational cosmic order. Motion and change is described as the actualization of potentials already in things, while the Socratics insisted that philosophy should be used to consider the practical question of the best way to live for a human being, they did not argue for any other types of applied science
18.
Surface science
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It includes the fields of surface chemistry and surface physics. Some related practical applications are classed as surface engineering, the science encompasses concepts such as heterogeneous catalysis, semiconductor device fabrication, fuel cells, self-assembled monolayers, and adhesives. Surface science is related to interface and colloid science. Interfacial chemistry and physics are common subjects for both, in addition, interface and colloid science studies macroscopic phenomena that occur in heterogeneous systems due to peculiarities of interfaces. The field of surface chemistry started with heterogeneous catalysis pioneered by Paul Sabatier on hydrogenation, irving Langmuir was also one of the founders of this field, and the scientific journal on surface science, Langmuir, bears his name. The Langmuir adsorption equation is used to model monolayer adsorption where all surface adsorption sites have the affinity for the adsorbing species. Gerhard Ertl in 1974 described for the first time the adsorption of hydrogen on a surface using a novel technique called LEED. Similar studies with platinum, nickel, and iron followed, Surface chemistry can be roughly defined as the study of chemical reactions at interfaces. Surface science is of importance to the fields of heterogeneous catalysis, electrochemistry. The adhesion of gas or liquid molecules to the surface is known as adsorption and this can be due to either chemisorption or physisorption, and the strength of molecular adsorption to a catalyst surface is critically important to the catalysts performance. However, it is difficult to study these phenomena in real catalyst particles, instead, well-defined single crystal surfaces of catalytically active materials such as platinum are often used as model catalysts. Results can be fed into chemical models or used toward the design of new catalysts. Reaction mechanisms can also be clarified due to the precision of surface science measurements. The behavior of an interface is affected by the distribution of ions within the electrical double layer. These studies link traditional electrochemical techniques such as cyclic voltammetry to direct observations of interfacial processes, geologic phenomena such as iron cycling and soil contamination are controlled by the interfaces between minerals and their environment. Surface physics can be defined as the study of physical changes that occur at interfaces. The study and analysis of surfaces involves both physical and chemical analysis techniques, several modern methods probe the topmost 1–10 nm of surfaces exposed to vacuum. Many of these techniques require vacuum as they rely on the detection of electrons or ions emitted from the surface under study, at 0.1 mPa, it only takes 1 second to cover a surface with a contaminant, so much lower pressures are needed for measurements
19.
Reverberation
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Reverberation, in psychoacoustics and acoustics, is the persistence of sound after a sound is produced. This is most noticeable when the sound source stops but the reflections continue, decreasing in amplitude, until they reach zero amplitude. In comparison to an echo that is a minimum of 50 to 100 ms after the initial sound. As time passes, the amplitude of the reflections is reduced until it is reduced to zero, Reverberation is not limited to indoor spaces as it exists in forests and other outdoor environments where reflection exists. Reverberation occurs naturally when a person sings, talks or plays an instrument acoustically in a hall or performance space with sound-reflective surfaces. The sound of reverberation is often added to the vocals of singers in live sound systems. The time it takes for a signal to drop by 60 dB is the reverberation time, RT60 is the time required for reflections of a direct sound to decay 60 dB. Reverberation time is stated as a single value, if measured as a wide band signal, however, being frequency dependent. Being frequency dependent, the time measured in narrow bands will differ depending on the frequency band being measured. For precision, it is important to know what ranges of frequencies are being described by a time measurement. In the late 19th century, Wallace Clement Sabine started experiments at Harvard University to investigate the impact of absorption on the reverberation time. Using a portable wind chest and organ pipes as a sound source and he found that the reverberation time is proportional to room dimensions and inversely proportional to the amount of absorption present. The optimum reverberation time for a space in which music is played depends on the type of music that is to be played in the space, rooms used for speech typically need a shorter reverberation time so that speech can be understood more clearly. If the reflected sound from one syllable is still heard when the syllable is spoken. Cat, Cab, and Cap may all sound very similar, if on the other hand the reverberation time is too short, tonal balance and loudness may suffer. Reverberation effects are used in studios to add depth to sounds. Reverberation changes the perceived spectral structure of a sound, but does not alter the pitch, basic factors that affect a rooms reverberation time include the size and shape of the enclosure as well as the materials used in the construction of the room. Every object placed within the enclosure can also affect this time, including people
20.
Heichal HaTarbut
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The Culture Palace or Charles Bronfman Auditorium is the biggest concert hall in Tel Aviv, Israel, and home to the Israel Philharmonic Orchestra. It was opened in 1957 at Habima Square, architects were Dov Karmi, Zeev Rechter and Yaakov Rechter. Leonard Bernstein conducted the concert, with the Israel Philharmonic and pianist Arthur Rubinstein. Until 2013, the palace was named Fredric R. Mann Auditorium, from 2011 to 2013, the auditorium was thoroughly renovated under the supervision of Israeli architect Ofer Kolker. Responsible for the new acoustics was Japanese Yasuhisa Toyota, in May 2013, the reopening of the auditorium took place with Gustav Mahlers 5th Symphony, performed by the Israel Philharmonic under their Music Director Zubin Mehta. Now the palace is called Charles Bronfman Auditorium, after Canadian / American businessman and philanthropist Charles Bronfman
21.
Perforated metal
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Materials used to manufacture perforated metal sheets include stainless steel, cold rolled steel, galvanized steel, brass, aluminum, tinplate, copper, Monel, Inconel, titanium, plastic, and more. The process of perforating metal sheets has been practiced for over 150 years, in the late 19th century, metal screens were use as an efficient means of separating coal. Unfortunately, the first perforators were laborers who would manually punch individual holes into the metal sheet, modern day perforation methods involve the use of technology and machines. Common equipment used for the perforation of metal include rotary pinned perforation rollers, die and punch presses, and laser perforations. Food & beverage - beehive construction, grain dryers, wine vats, fish farming, silo ventilation, sorting machines, fruit and vegetable juice presses, cheese molds, baking trays, coffee screens, etc. Chemical & energy - filters, centrifuges, drying machine baskets, battery plates, water screens, gas purifiers, liquid gas burning tubes, mine cages, coal washing. Material development - glass reinforcement, cement slurry screens, dyeing machines, textile printers and felt mills, cinder screens, blast furnace screens, etc. Automotive - air filters, oil filters, silencer tubes, radiator grilles, running boards, flooring, motorcycle silencers, ventilation grids, tractor engine ventilation, etc. Construction - ceiling noise protection, acoustic panels, stair treads, pipe guards, ventilation grilles, sun protection slats, facades, sign boards, the acoustic performance of perforated metal helps people or workers to limit health effects from noise. Studies have shown that perforated metals help reduce sound levels, studies have shown that having buildings use perforated metal sheets in front of their façade can bring in one study 29% energy savings and in the second one 45% energy savings. Depending on the location of the building, solar irradiation can be decrease by 77. 9%
22.
Classroom
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A classroom is a learning space, a room in which classes are held. The classroom attempts to provide a space where learning can take place uninterrupted by outside distractions, for lessons that require specific resources or a vocational approach different types of classrooms both indoors and outdoors are used. This allows for learning in a context that fosters the natural development of the particular vocational skill. This is known as situated learning, classrooms can range from small groups of five or six to big classrooms with hundreds of students. A large class room is called a lecture hall. A few examples of classrooms are computer labs which are used for IT lessons in schools, gymnasiums for sports, there are also small group classrooms where students learn in groups of about 7 or less. Most classrooms have a writing surface where the instructor or students can share notes with other members of the class. Traditionally, this was in the form of a blackboard but these are becoming common in well-equipped schools because of new alternatives like flipcharts, whiteboards. Many classrooms also have TVs, maps, charts, pencils, books, monographs and LCD projectors for presenting information, in the past, schools and institutions would often have one computer lab that served the entire school only at certain times of the week. Computers in the classroom itself increase interest in learning and awareness of the importance of what is being taught, children are less likely to feel that a subject is archaic if the teacher uses new technological instructional techniques, increasing the students’ interest in learning something new. A study shows that children taught with the integration of technology improved in testing significantly over those who did not, the Classroom of the Future is an education project in the United Kingdom. Twelve local education authorities sharing about £13 million to develop around 30 pilot projects, the buildings have roughly three classrooms in them, which contain enough laptops or tablet computers for each person. The classrooms are designed to be environmentally friendly, the buildings contain toilets which use rainwater, and use windturbines and solar panels for electricity and heating. Both the facilities and the curriculum of educational institutions can be organized in different models, including the configuration of individual classrooms, clusters and these include departmental, academies, integrated, learning communities, and school-within-a-school models. The layout, design and decor of the classroom has a significant effect upon the quality of the educational experience, attention to the acoustics and colour scheme may reduce distractions and aid concentration. The lighting and furniture likewise influence factors such as student attention span, historically, relatively few pupil-centric design principles were used in the construction of classrooms. Desks were often arranged in columns and rows, with a desk at the front. Little color was used for fear of distracting the children, in the 1950s and 60s cheap and harsh fluorescent lights were sometimes used, which could cause eyestrain
23.
Anechoic chamber
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An anechoic chamber is a room designed to completely absorb reflections of either sound or electromagnetic waves. They are also isolated from waves entering from their surroundings. This combination means that a person or detector exclusively hears direct sounds, Anechoic chambers, a term coined by American acoustics expert Leo Beranek, were initially exclusively used to refer to acoustic anechoic chambers. Recently, the term has been extended to RF anechoic chambers, Anechoic chambers range from small compartments the size of household microwave ovens to ones as large as aircraft hangars. The size of the chamber depends on the size of the objects, Anechoic chambers are commonly used in acoustics to conduct experiments in nominally free field conditions, free-field meaning that there are no reflected signals. All sound energy will be traveling away from the source with almost none reflected back, common anechoic chamber experiments include measuring the transfer function of a loudspeaker or the directivity of noise radiation from industrial machinery. In general, the interior of a chamber is very quiet. In 2005, the best anechoic chamber measured at −9.4 dBA, in 2015, an anechoic chamber on the campus of Microsoft broke the world record with a measurement of −20.6 dBA. The human ear can detect sounds above 0 dBA, so a human in such a chamber would perceive the surroundings as devoid of sound. Anecdotally, some humans may not like such quietness and can become disoriented and this wall is composed of a series of wedges W with height H. After the impingement, the incident wave I is reflected as a series of waves R which in turn bounce up-and-down in the gap of air A between the wedges W, such bouncing may produce a standing wave pattern in A. During this process, the energy of the waves R gets dissipated via the airs molecular viscosity. In addition, with the use of materials to fabricate the wedges. As a result, the component of the reflected waves R along the direction of I that escapes the gaps A, even though this explanation is two-dimensional, it is representative and applicable to the actual three-dimensional wedge structures used in anechoic chambers. Full anechoic chambers aim to absorb energy in all directions and this floor is damped and floating on absorbent buffers to isolate it from outside vibration or electromagnetic signals. Uses for RF anechoic chambers include testing antennae, radars, and is used to house the equipment for performing measurements of antenna radiation patterns. Performance expectations constitute primary challenges in designing stand alone or embedded antennae, designs are becoming ever more complex with a single device incorporating multiple technologies such as cellular, WiFi, Bluetooth, LTE, MIMO, RFID and GPS. RAM is designed and shaped to absorb incident RF radiation as effectively as possible, the more effective the RAM, the lower the resulting level of reflected RF radiation
24.
Textile
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A textile or cloth is a flexible material consisting of a network of natural or artificial fibres. Yarn is produced by spinning raw fibres of wool, flax, cotton, hemp, Textiles are formed by weaving, knitting, crocheting, knotting, or felting. The words fabric and cloth are used in textile assembly trades as synonyms for textile, however, there are subtle differences in these terms in specialized usage. Textile refers to any material made of interlacing fibres, a fabric is a material made through weaving, knitting, spreading, crocheting, or bonding that may be used in production of further goods. Cloth may be used synonymously with fabric but is often a piece of fabric used for a specific purpose. The word textile is from Latin, from the adjective textilis, meaning woven, from textus, the word cloth derives from the Old English clað, meaning a cloth, woven or felted material to wrap around one, from Proto-Germanic kalithaz. The discovery of dyed flax fibres in a cave in the Republic of Georgia dated to 34,000 BCE suggests textile-like materials were made even in prehistoric times. The production of textiles is a craft whose speed and scale of production has been altered almost beyond recognition by industrialization, however, for the main types of textiles, plain weave, twill, or satin weave, there is little difference between the ancient and modern methods. Textiles have an assortment of uses, the most common of which are for clothing and for such as bags. In the household they are used in carpeting, upholstered furnishings, window shades, towels, coverings for tables, beds, and other flat surfaces, in the workplace they are used in industrial and scientific processes such as filtering. Textiles are used in traditional crafts such as sewing, quilting. Textiles for industrial purposes, and chosen for other than their appearance, are commonly referred to as technical textiles. Technical textiles include textile structures for applications, medical textiles, geotextiles, agrotextiles. In all these applications stringent performance requirements must be met, woven of threads coated with zinc oxide nanowires, laboratory fabric has been shown capable of self-powering nanosystems using vibrations created by everyday actions like wind or body movements. Fashion designers commonly rely on textile designs to set their fashion collections apart from others, armani, the late Gianni Versace, and Emilio Pucci can be easily recognized by their signature print driven designs. Textiles can be made from many materials and these materials come from four main sources, animal, plant, mineral, and synthetic. In the past, all textiles were made from natural fibres, including plant, animal, in the 20th century, these were supplemented by artificial fibres made from petroleum. Textiles are made in various strengths and degrees of durability, from the finest gossamer to the sturdiest canvas, microfibre refers to fibres made of strands thinner than one denier
25.
HVAC
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Heating, ventilation and air conditioning is the technology of indoor and vehicular environmental comfort. Its goal is to provide comfort and acceptable indoor air quality. HVAC system design is a subdiscipline of mechanical engineering, based on the principles of thermodynamics, fluid mechanics, Refrigeration is sometimes added to the fields abbreviation as HVAC&R or HVACR, or ventilating is dropped as in HACR. Ventilation removes unpleasant smells and excessive moisture, introduces outside air, keeps interior building air circulating, ventilation includes both the exchange of air to the outside as well as circulation of air within the building. It is one of the most important factors for maintaining acceptable indoor air quality in buildings, methods for ventilating a building may be divided into mechanical/forced and natural types. HVAC systems can be used in domestic and commercial environments. HVAC systems can provide ventilation, reduce air infiltration, and maintain pressure relationships between spaces, the means of air delivery and removal from spaces is known as room air distribution. In modern buildings the design, installation, and control systems of functions are integrated into one or more HVAC systems. For very small buildings, contractors normally estimate the capacity, engineer, for larger buildings, building service designers, mechanical engineers, or building services engineers analyze, design, and specify the HVAC systems. Specialty mechanical contractors then fabricate and commission the systems, Building permits and code-compliance inspections of the installations are normally required for all sizes of building. HVAC is based on inventions and discoveries made by Nikolay Lvov, Michael Faraday, Willis Carrier, Edwin Ruud, Reuben Trane, James Joule, William Rankine, Sadi Carnot, heaters are appliances whose purpose is to generate heat for the building. This can be done via central heating, such a system contains a boiler, furnace, or heat pump to heat water, steam, or air in a central location such as a furnace room in a home, or a mechanical room in a large building. The heat can be transferred by convection, conduction, or radiation, heaters exist for various types of fuel, including solid fuels, liquids, and gases. Another type of source is electricity, normally heating ribbons composed of high resistance wire. This principle is used for baseboard heaters and portable heaters. Electrical heaters are used as backup or supplemental heat for heat pump systems. The heat pump gained popularity in the 1950s in Japan and the United States, heat pumps can extract heat from various sources, such as environmental air, exhaust air from a building, or from the ground. In the case of heated water or steam, piping is used to transport the heat to the rooms, most modern hot water boiler heating systems have a circulator, which is a pump, to move hot water through the distribution system
26.
North America
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North America is a continent entirely within the Northern Hemisphere and almost all within the Western Hemisphere. It can also be considered a subcontinent of the Americas. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the west and south by the Pacific Ocean, and to the southeast by South America and the Caribbean Sea. North America covers an area of about 24,709,000 square kilometers, about 16. 5% of the land area. North America is the third largest continent by area, following Asia and Africa, and the fourth by population after Asia, Africa, and Europe. In 2013, its population was estimated at nearly 565 million people in 23 independent states, or about 7. 5% of the worlds population, North America was reached by its first human populations during the last glacial period, via crossing the Bering land bridge. The so-called Paleo-Indian period is taken to have lasted until about 10,000 years ago, the Classic stage spans roughly the 6th to 13th centuries. The Pre-Columbian era ended with the migrations and the arrival of European settlers during the Age of Discovery. Present-day cultural and ethnic patterns reflect different kind of interactions between European colonists, indigenous peoples, African slaves and their descendants, European influences are strongest in the northern parts of the continent while indigenous and African influences are relatively stronger in the south. Because of the history of colonialism, most North Americans speak English, Spanish or French, the Americas are usually accepted as having been named after the Italian explorer Amerigo Vespucci by the German cartographers Martin Waldseemüller and Matthias Ringmann. Vespucci, who explored South America between 1497 and 1502, was the first European to suggest that the Americas were not the East Indies, but a different landmass previously unknown by Europeans. In 1507, Waldseemüller produced a map, in which he placed the word America on the continent of South America. He explained the rationale for the name in the accompanying book Cosmographiae Introductio, for Waldseemüller, no one should object to the naming of the land after its discoverer. He used the Latinized version of Vespuccis name, but in its feminine form America, following the examples of Europa, Asia and Africa. Later, other mapmakers extended the name America to the continent, In 1538. Some argue that the convention is to use the surname for naming discoveries except in the case of royalty, a minutely explored belief that has been advanced is that America was named for a Spanish sailor bearing the ancient Visigothic name of Amairick. Another is that the name is rooted in a Native American language, the term North America maintains various definitions in accordance with location and context. In Canadian English, North America may be used to refer to the United States, alternatively, usage sometimes includes Greenland and Mexico, as well as offshore islands
27.
Elevator
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An elevator or lift is a type of vertical transportation that moves people or goods between floors of a building, vessel, or other structure. Elevators are generally powered by electric motors that either drive traction cables or counterweight systems like a hoist, in agriculture and manufacturing, an elevator is any type of conveyor device used to lift materials in a continuous stream into bins or silos. Several types exist, such as the chain and bucket elevator, grain auger screw conveyor using the principle of Archimedes screw, or the chain, languages other than English may have loanwords based on either elevator or lift. Because of wheelchair access laws, elevators are often a requirement in new multistory buildings. The earliest known reference to an elevator is in the works of the Roman architect Vitruvius, some sources from later historical periods mention elevators as cabs on a hemp rope powered by hand or by animals. In 1000, the Book of Secrets by al-Muradi in Islamic Spain described the use of a lifting device. In the 17th century the prototypes of elevators were located in the buildings of England. Louis XV of France had a flying chair built for one of his mistresses at the Chateau de Versailles in 1743. Ancient and medieval elevators used drive systems based on hoists or winders, the invention of a system based on the screw drive was perhaps the most important step in elevator technology since ancient times, leading to the creation of modern passenger elevators. The first screw drive elevator was built by Ivan Kulibin and installed in Winter Palace in 1793, several years later another of Kulibins elevators was installed in Arkhangelskoye near Moscow. The development of elevators was led by the need for movement of raw materials including coal, the technology developed by these industries and the introduction of steel beam construction worked together to provide the passenger and freight elevators in use today. Starting in the mines, by the mid-19th century elevators were operated with steam power and were used for moving goods in bulk in mines and factories. It elevated paying customers to a height in the center of London. Early, crude steam-driven elevators were refined in the decade, – in 1835 an innovative elevator called the Teagle was developed by the company Frost. The elevator was belt-driven and used a counterweight for extra power, the hydraulic crane was invented by Sir William Armstrong in 1846, primarily for use at the Tyneside docks for loading cargo. These quickly supplanted the steam driven elevators, exploiting Pascals law. A water pump supplied a variable level of pressure to a plunger encased inside a vertical cylinder. Counterweights and balances were used to increase the lifting power of the apparatus
28.
Electric generator
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In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, the first electromagnetic generator, the Faraday disk, was built in 1831 by British scientist Michael Faraday. Generators provide nearly all of the power for electric power grids, the reverse conversion of electrical energy into mechanical energy is done by an electric motor, and motors and generators have many similarities. Many motors can be driven to generate electricity and frequently make acceptable manual generators. Electromagnetic generators fall into one of two categories, dynamos and alternators. The magnetic field of the dynamo or alternator can be provided by either wire windings called field coils or permanent magnets, a generator using permanent magnets is sometimes called a magneto. Armature, The power-producing component of an electrical machine, in a generator, alternator, or dynamo the armature windings generate the electric current, which provides power to an external circuit. The armature can be on either the rotor or the stator, depending on the design, before the connection between magnetism and electricity was discovered, electrostatic generators were invented. They operated on electrostatic principles, by using moving electrically charged belts, plates, the charge was generated using either of two mechanisms, electrostatic induction or the triboelectric effect. Such generators generated very high voltage and low current and their only practical applications were to power early X-ray tubes, and later in some atomic particle accelerators. The operating principle of electromagnetic generators was discovered in the years of 1831–1832 by Michael Faraday, the principle later called Faradays law, is that an electromotive force is generated in an electrical conductor which encircles a varying magnetic flux. He also built the first electromagnetic generator, called the Faraday disk and it produced a small DC voltage. This design was inefficient, due to self-cancelling counterflows of current in regions of the disk that were not under the influence of the magnetic field. While current was induced directly underneath the magnet, the current would circulate backwards in regions that were outside the influence of the magnetic field and this counterflow limited the power output to the pickup wires, and induced waste heating of the copper disc. Later homopolar generators would solve this problem by using an array of magnets arranged around the perimeter to maintain a steady field effect in one current-flow direction. Another disadvantage was that the voltage was very low, due to the single current path through the magnetic flux. Experimenters found that using multiple turns of wire in a coil could produce higher, since the output voltage is proportional to the number of turns, generators could be easily designed to produce any desired voltage by varying the number of turns. Wire windings became a feature of all subsequent generator designs
29.
Vibration isolation
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Vibration isolation is the process of isolating an object, such as a piece of equipment, from the source of vibrations. Vibration is undesirable in many domains, primarily engineered systems and habitable spaces, vibrations propagate via mechanical waves and certain mechanical linkages conduct vibrations more efficiently than others. Passive vibration isolation makes use of materials and mechanical linkages that absorb, Active vibration isolation involves sensors and actuators that produce destructive interference that cancels-out incoming vibration. Passive vibration isolation is a vast subject, since there are types of passive vibration isolators used for many different applications. A source of compressed air is required to maintain them, air springs are rubber bladders which provide damping as well as isolation and are used in large trucks. Some pneumatic isolators can attain low resonant frequencies and are used for isolating large industrial equipment, air tables consist of a working surface or optical surface mounted on air legs. These tables provide enough isolation for laboratory instrument under some conditions, air systems may leak under vacuum conditions. The air container can interfere with isolation of low-amplitude vibration, mechanical springs and spring-dampers These are heavy-duty isolators used for building systems and industry. Sometimes they serve as mounts for a block, which provides further isolation. Pads or sheets of materials such as elastomers, rubber, cork, dense foam. Elastomer pads, dense closed cell foams and laminate materials are used under heavy machinery, under common household items, in vehicles. Molded and bonded rubber and elastomeric isolators and mounts These are often used as mounts or in vehicles. They absorb shock and attenuate some vibration, Negative-stiffness isolators Negative-stiffness isolators are less common than other types and have generally been developed for high-level research applications such as gravity wave detection. Lee, Goverdovskiy, and Temnikov proposed a system for isolating vehicle seats. All higher frequencies are also isolated, Negative-stiffness systems can be made with low stiction, so that they are effective in isolating low-amplitude vibrations. Negative-stiffness mechanisms are mechanical and typically involve the configuration and loading of components such as beams or inverted pendulums. Greater loading of the mechanism, within the range of its operability. Wire rope isolators These isolators are durable and can withstand extreme environments and they are often used in military applications
30.
Sound masking
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Sound masking is the addition of sound created by special digital generators and distributed by normally unseen speakers through an area to reduce distractions or provide confidentiality where needed. The sound is broad band random that conveys no information about itself to a listener and it is often referred to erroneously as white noise or pink noise, the sound spectrum and level is specially shaped to provide the degree of privacy desired by occupants. Masking operates by covering up or masking unwanted sounds, similar to perfume that covers up other odors and this is in contrast to the technique of active noise control which attempts to eliminate the unwanted sound. Sound masking is used in homes, commercial offices, medical facilities, court rooms, based on Sound Masking Done Right. A seminal work covers the subject in some detail, Noise is defined as unwanted sound. It can have three effects depending mostly on level, at high levels, there are mechanical changes in a person, such as heating of the skin, rupture of the eardrum, or vibration of the eyeballs or internal organs. At lower levels, there are changes in a person, such as elevation of blood pressure. At still lower levels, the changes are such as annoyance. Annoyance is based on such as the persons evaluation of the necessity of the noise, or whether it can be controlled. The levels of masking are sufficiently low that they have no known physical or physiological effects on people. One aim of sound masking design is to make the sound be normal, since most sound masking is used in offices, a number of cognitive psychology studies have been made that relate specifically to the office environment. One study found there was a modest stress increase and diminished motivation caused by typical office noises. It is recommended that the use of masking is under the control of the worker. Another study suggested that changes in level are an important factor, in the office, habituation can be interpreted to mean I’ve grown used to the noise and it no longer distracts me or Since I cannot do anything about it, I will have to live with it. Another study point out that the information within the speech intrusion is not important nor is the intensity of the sound between 48 and 76 dBA. Since the energy level of the sound was 1,000 times that of the least. For arithmetic tasks, both speech and non-verbal intrusive noises caused significant performance decreases, for prose tasks it was found that speech caused a greater performance decrease than nonverbal noises. In another study the author added several significant observations and it was found that during a serial recall task, the accuracy of report decreases 30 to 50%
31.
Health effects from noise
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Noise health effects are the health consequences of regular exposure, to consistent elevated sound levels. Elevated workplace or environmental noise can cause hearing impairment, hypertension, ischemic heart disease, annoyance, changes in the immune system and birth defects have been also attributed to noise exposure. Noise exposure also has known to induce tinnitus, hypertension, vasoconstriction. Beyond these effects, elevated noise levels can create stress, increase workplace accident rates, the most significant causes are vehicle and aircraft noise, prolonged exposure to loud music, and industrial noise. In Norway, road traffic has been demonstrated to cause almost 80% of the annoyances reported. There may be psychological definitions of noise as well, firecrackers may upset domestic and wild animals or noise-traumatized individuals. The most common noise-traumatized persons are exposed to military conflicts. Infants are easily startled by noise, the social costs of traffic noise in EU22 are more than €40 billion per year, and passenger cars and lorries are responsible for bulk of costs. Traffic noise alone is harming the health of almost every person in the WHO European Region. One in five Europeans is regularly exposed to levels at night that could significantly damage health. Noise also is a threat to species in marine and terrestrial ecosystems alike. Underlying pathology to the cochlea are reactive species, which play a significant role in noise-induced necrosis and apoptosis of the stereocilia. The elevated sound levels cause trauma to cochlear structure in the inner ear, the outer ear combined with the middle ear amplifies sound levels by a factor of 20 when sound reaches the inner ear. Hearing loss is inevitable with age. Though older males exposed to significant occupational noise demonstrate significantly reduced hearing sensitivity compared to non-exposed peers, differences in hearing sensitivity decrease with time and the two groups are indistinguishable by age 79. Over time, the detection of high-pitched sound frequencies becomes more difficult and this affects speech perception, particularly of those words involving sibilants and fricatives. Both ears tend to be affected, women exposed to occupational noise do not differ from their peers in hearing sensitivity, although they do hear better than their non-exposed male counterparts. Consistent exposure to music, young people in the United States have a rate of impaired hearing 2.5 times greater than their parents and grandparents
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Noise control
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Noise control or noise mitigation is a set of strategies to reduce noise pollution or to reduce the impact of that noise, whether outdoors or indoors. The main areas of noise mitigation or abatement are, transportation noise control, architectural design, urban planning through zoning codes, roadway noise and aircraft noise are the most pervasive sources of environmental noise. Many of these techniques rely upon materials science applications of constructing sound baffles or using sound-absorbing liners for interior spaces, sound masking is the active addition of noise to reduce the annoyance of certain sounds, the opposite of soundproofing. Sound insulation, prevent the transmission of noise by the introduction of a mass barrier, common materials have high-density properties such as brick, thick glass, concrete, metal etc. Sound absorption, a material which acts as a ‘noise sponge’ by converting the sound energy into heat within the material. Common sound absorption materials include decoupled lead-based tiles, open cell foams and fiberglass Vibration damping, the damping mechanism works by extracting the vibration energy from the thin sheet and dissipating it as heat. A common material is sound deadened steel, Vibration isolation, prevents transmission of vibration energy from a source to a receiver by introducing a flexible element or a physical break. Common vibration isolators are springs, rubber mounts, cork etc, highway noise is today less affected by motor type, since the effects in higher speed are aerodynamic and tire noise related. The most fertile areas for roadway noise mitigation are in planning decisions, roadway design, noise barrier design, speed control, surface pavement selection. Speed control is effective since the lowest sound emissions arise from vehicles moving smoothly at 30 to 60 kilometres per hour, above that range, sound emissions double with each five miles per hour of speed. At the lowest speeds, braking and acceleration noise dominates, selection of road surface pavement can make a difference of a factor of two in sound levels, for the speed regime above 30 kilometres per hour. Surface friction and roadway safety are important considerations as well for pavement decisions, when designing new urban freeways or arterials, there are numerous design decisions regarding alignment and roadway geometrics. Use of a model to calculate sound levels has become standard practice since the early 1970s. In this way exposure of sensitive receptors to elevated sound levels can be minimized, an analogous process exists for urban mass transit systems and other rail transportation decisions. Noise barriers can be applicable for existing or planned surface transportation projects and they are probably the single most effective weapon in retrofitting an existing roadway, and commonly can reduce adjacent land use sound levels by up to ten decibels. A computer model is required to design the barrier since terrain, micrometeorology, for example, a roadway in cut or strong prevailing winds can produce a setting where atmospheric sound propagation is unfavorable to any noise barrier. As in the case of noise, little progress has been made in quelling aircraft noise at the source, other than elimination of loud engine designs from the 1960s. Because of its velocity and volume, jet engine exhaust noise defies reduction by any simple means
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Noise regulation
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Noise regulation includes statutes or guidelines relating to sound transmission established by national, state or provincial and municipal levels of government. After the watershed passage of the United States Noise Control Act of 1972, other local, a noise regulation restricts the amount of noise, the duration of noise and the source of noise. It usually places restrictions for certain times of the day, in the 1960s and earlier, few people recognized that citizens might be entitled to be protected from adverse sound level exposure. Most concerted actions consisted of groups organized to oppose a specific highway or airport. Passage of the NCA was remarkable considering the lack of historic organized citizen concern, many municipalities do not follow up on complaints. Even where a municipality has an enforcement office, it may only be willing to issue warnings, japan actually passed the first national noise control act, but its scope was much more limited than the U. S. law, addressing mainly workplace and construction noise. Initially these laws had a significant effect on thoughtful study of transportation programs and they also gave states and cities an impetus to consider environmental noise in their planning and zoning decisions, and led to a host of statutes below the federal level. Awareness of the need for control was rising. In fact, by 1973 a national poll of 60,000 U. S. residents found that sixty percent of people considered street noise to have a disturbing, harmful or dangerous impact. This trend continued throughout the 1970s in the U. S. with about half of the states. Noise regulation subsided sharply in 1981, when Congress ended funding for the NCA, EPA had pre-empted lower levels of government from regulating sources, so states could not legislate standards such as for truck noise emissions. Nevertheless, some continued to act. Many cities throughout the U. S. also have noise ordinances and these ordinances can be enforced with local police powers. Several European countries emulated the U. S. national noise control law, Netherlands, France, Spain, in some cases unlegislated innovations have led to quieter products exceeding legal mandates. Environmental noise is a definition in the European directive 2002/49/EC article 10.1. The U. S. activities lag by 10 to 20 years behind most European countries, russia, China and undeveloped countries lag even further behind. After the passage of the NCA, EPA promulgated regulations setting maximum noise limits on a gamut of motor vehicles, industrial machinery, the Agency conducted extensive testing and consulted with industry on the practicality of manufacturing quieter devices. EPAs efforts had an influence on the future of a generation of machines
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Noise, vibration, and harshness
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Noise, vibration, and harshness, also known as noise and vibration, is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks. These latter tools belong to the known as psychoacoustics. NVH is mostly engineering, but often objective measurements fail to predict or correlate well with the impression on human observers. For example, although the response at moderate noise levels is approximated by A-weighting. The field of psychoacoustics is partly concerned with this correlation, in some cases the NVH engineer is asked to change the sound quality, by adding or subtracting particular harmonics, rather than making the vehicle quieter. The sources of noise in a vehicle are many, including the engine, driveline, tire patch and road surface, brakes. Noise from cooling fans, or the HVAC, alternator, many problems are generated as either vibration or noise, transmitted via a variety of paths, and then radiated acoustically into the cabin. These are classified as structure-borne noise, others are generated acoustically and propagated by airborne paths. Structure-borne noise is attenuated by isolation, while noise is reduced by absorption or through the use of barrier materials. Vibrations are sensed at the wheel, the seat, armrests, or the floor. Some resonant systems respond at characteristic frequencies, but in response to random excitation, therefore, although they look like tonal problems on any one spectrum, their amplitude varies considerably. Other problems are self resonant, such as whistles from antennas, here is the noise spectrum of Michael Schumachers Ferrari at 16680 rpm, showing the various harmonics. The x axis is given in terms of multiples of engine speed, the y axis is logarithmic, and uncalibrated. Typical instrumentation used to measure NVH include microphones, accelerometers and force gauges, many NVH facilities will have semi-anechoic chambers, and rolling road dynamometers. Typically signals are recorded direct to hard disk via an analog-to-digital converter, in the past magnetic or DAT tape recorders were used. The integrity of the chain is very important, typically each of the instruments used are fully calibrated in a lab once per year. Laser scanning vibrometry is an tool for effective NVH optimization. The vibrational characteristics of a sample is acquired full field under operational or excited conditions, the results represent the actual vibrations
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International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
36.
Acoustics
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Acoustics is the interdisciplinary science that deals with the study of all mechanical waves in gases, liquids, and solids including topics such as vibration, sound, ultrasound and infrasound. A scientist who works in the field of acoustics is an acoustician while someone working in the field of technology may be called an acoustical engineer. The application of acoustics is present in almost all aspects of society with the most obvious being the audio. Hearing is one of the most crucial means of survival in the animal world, accordingly, the science of acoustics spreads across many facets of human society—music, medicine, architecture, industrial production, warfare and more. Likewise, animal species such as songbirds and frogs use sound, art, craft, science and technology have provoked one another to advance the whole, as in many other fields of knowledge. Robert Bruce Lindsays Wheel of Acoustics is a well accepted overview of the fields in acoustics. The word acoustic is derived from the Greek word ἀκουστικός, meaning of or for hearing, ready to hear and that from ἀκουστός, heard, audible, which in turn derives from the verb ἀκούω, I hear. The Latin synonym is sonic, after which the term used to be a synonym for acoustics. Frequencies above and below the range are called ultrasonic and infrasonic. If, for example, a string of a length would sound particularly harmonious with a string of twice the length. In modern parlance, if a string sounds the note C when plucked, a string twice as long will sound a C an octave lower. In one system of tuning, the tones in between are then given by 16,9 for D,8,5 for E,3,2 for F,4,3 for G,6,5 for A. Aristotle understood that sound consisted of compressions and rarefactions of air which falls upon, a very good expression of the nature of wave motion. The physical understanding of acoustical processes advanced rapidly during and after the Scientific Revolution, mainly Galileo Galilei but also Marin Mersenne, independently, discovered the complete laws of vibrating strings. Experimental measurements of the speed of sound in air were carried out successfully between 1630 and 1680 by a number of investigators, prominently Mersenne, meanwhile, Newton derived the relationship for wave velocity in solids, a cornerstone of physical acoustics. The eighteenth century saw advances in acoustics as mathematicians applied the new techniques of calculus to elaborate theories of sound wave propagation. Also in the 19th century, Wheatstone, Ohm, and Henry developed the analogy between electricity and acoustics, the twentieth century saw a burgeoning of technological applications of the large body of scientific knowledge that was by then in place. The first such application was Sabine’s groundbreaking work in architectural acoustics, Underwater acoustics was used for detecting submarines in the first World War
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Monochord
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A monochord, also known as sonometer, is an ancient musical and scientific laboratory instrument, involving one string. The term monochord is sometimes used as the class-name for any musical stringed instrument having only one string, according to the Hornbostel–Sachs system, string bows are bar zithers while monochords are traditionally board zithers. A string is fixed at both ends and stretched over a sound box, one or more movable bridges are then manipulated to demonstrate mathematical relationships among the frequencies produced. With its single string, movable bridge and graduated rule, the monochord straddled the gap between notes and numbers, intervals and ratios, sense-perception and mathematical reason, however, music, mathematics, and astronomy were inexorably linked in the monochord. For example, when a string is open it vibrates at a particular frequency. When the length of the string is halved, and plucked, it produces a pitch an octave higher, half of this length will produce a pitch two octaves higher than the original—four times the initial frequency —and so on. Standard diatonic Pythagorean tuning is easily derived starting from superparticular ratios, /n, constructed from the first four counting numbers, the mathematics involved include the multiplication table, least common multiples, and prime and composite numbers. A bichord instrument is one, having two strings in unison for each note, such as the mandolin, with two strings one can easily demonstrate how various musical intervals sound. Parts of a monochord include a tuning peg, nut, string, moveable bridge, fixed bridge, calibration marks, belly or resonating box, instruments derived from the monochord include the guqin, dan bau, koto, vina, hurdy-gurdy, and clavichord. A monopipe is the wind instrument version of a monochord, an open pipe which can produce variable pitches. End correction must be used with this method, to achieve accuracy, the monochord is mentioned in Sumerian writings, while some attribute its invention to Pythagorus. Dolge attributes the invention of the bridge to Guido of Arezzo around 1000 CE. In 1618, Robert Fludd devised a mundane monochord that linked the Ptolemaic universe to musical intervals, was it physical intuition or a Pythagorean confidence in the importance of small whole numbers. 1,5 &10, which is music that uses pitch ratios extended to higher partials beyond the standard Pythagorean tuning system. A modern playing technique used in rock as well as contemporary classical music is 3rd bridge. This technique shares the same mechanism as used on the monochord, a sonometer is a diagnostic instrument used to measure the tension, frequency or density of vibrations. They are used in medical settings to test both hearing and bone density, a sonometer, or audiometer, is used to determine hearing sensitivity, while a clinical bone sonometer measures bone density to help determine such conditions as the risk of osteoporosis. In audiology, the device is used to test for hearing loss, the audiometer measures the ability to hear sounds at frequencies normally detectable by the human ear
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Soundproofing
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Soundproofing is any means of reducing the sound pressure with respect to a specified sound source and receptor. Two distinct soundproofing problems may need to be considered when designing acoustic treatments - to improve the sound within a room, acoustic quieting, noise mitigation, and noise control can be used to limit unwanted noise. Soundproofing can suppress unwanted indirect sound waves such as reflections that cause echoes and resonances that cause reverberation, soundproofing can reduce the transmission of unwanted direct sound waves from the source to an involuntary listener through the use of distance and intervening objects in the sound path. The energy density of sound waves decreases as they spread out, in a normal three-dimensional setting, with a point source and point receptor, the intensity of sound waves will be attenuated according to the inverse square of the distance from the source. Damping means to reduce resonance in the room, by absorption or redirection, absorption will reduce the overall sound level, whereas redirection makes unwanted sound harmless or even beneficial by reducing coherence. Damping can reduce the acoustic resonance in the air, or mechanical resonance in the structure of the room itself or things in the room. Absorbing sound spontaneously converts part of the energy to a very small amount of heat in the intervening object. There are several ways in which a material can absorb sound, the choice of sound absorbing material will be determined by the frequency distribution of noise to be absorbed and the acoustic absorption profile required. Porous absorbers, typically open cell rubber foams or melamine sponges, porous open cell foams are highly effective noise absorbers across a broad range of medium-high frequencies. Performance is less impressive at low frequencies, unlike porous absorbers, resonant absorbers are most effective at low-medium frequencies and the absorption of resonant absorbers is always matched to a narrow frequency range. In an outdoor environment such as engineering, embankments or panelling are often used to reflect sound upwards into the sky. If a specular reflection from a flat surface is giving a problematic echo then an acoustic diffuser may be applied to the surface. It will scatter sound in all directions and this is effective to eliminate pockets of noise in a room. A room within a room is one method of isolating sound, most vibration / sound transfer from a room to the outside occurs through mechanical means. The vibration passes directly through the brick, woodwork and other structural elements. When it meets with an element such as a wall, ceiling, floor or window, which acts as a sounding board, a mechanical transmission is much faster, more efficient and may be more readily amplified than an airborne transmission of the same initial strength. The use of foam and other absorbent means is less effective against this transmitted vibration. The user is advised to break the connection between the room contains the noise source and the outside world
39.
String vibration
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A vibration in a string is a wave. Resonance causes a string to produce a sound with constant frequency. If the length or tension of the string is correctly adjusted, vibrating strings are the basis of string instruments such as guitars, cellos, and pianos. Let Δ x be the length of a piece of string, m its mass, and μ its linear density. If the horizontal component of tension in the string is a constant, T, if both angles are small, then the tensions on either side are equal and the net horizontal force is zero. This is the equation for y, and the coefficient of the second time derivative term is equal to v −2, thus v = T μ. Once the speed of propagation is known, the frequency of the produced by the string can be calculated. The speed of propagation of a wave is equal to the wavelength λ divided by the period τ, or multiplied by the frequency f, v = λ τ = λ f. If the length of the string is L, the harmonic is the one produced by the vibration whose nodes are the two ends of the string, so L is half of the wavelength of the fundamental harmonic. Hence one obtains Mersennes laws, f = v 2 L =12 L T μ where T is the tension, μ is the linear density, and L is the length of the vibrating part of the string. This effect is called the effect, and the rate at which the string seems to vibrate is the difference between the frequency of the string and the refresh rate of the screen. The same can happen with a fluorescent lamp, at a rate that is the difference between the frequency of the string and the frequency of the alternating current. In daylight and other non-oscillating light sources, this effect does not occur and the string appears still but thicker, a similar but more controllable effect can be obtained using a stroboscope. This device allows matching the frequency of the flash lamp to the frequency of vibration of the string. In a dark room, this shows the waveform. Otherwise, one can use bending or, perhaps more easily, by adjusting the machine heads, to obtain the same, or a multiple, of the AC frequency to achieve the same effect. For example, in the case of a guitar, the 6th string pressed to the third gives a G at 97.999 Hz. A slight adjustment can alter it to 100 Hz, exactly one octave above the current frequency in Europe and most countries in Africa
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String resonance
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String resonance occurs on string instruments. Strings or parts of strings may resonate at their fundamental or overtone frequencies when other strings are sounded, for example, an A string at 440 Hz will cause an E string at 330 Hz to resonate, because they share an overtone of 1320 Hz. Electric guitars can have string trees near the tuning pegs to mute this type of reverberation, the string length behind the bridge also must be as short as possible to prevent the resonance. String resonance is a factor in the timbre of a string instrument, tailed bridge guitars like the Fender Jaguar differ in timbre from guitars with short bridges, because of their floating bridge. The Japanese Koto is also an example of an instrument with occurring string resonance, sometimes string resonance is used in the construction of the instrument, like for instance the Sympathetic strings in many Eastern instruments. In the octave duplex piano by Hoerr of Toronto, each note had four strings, the following table shows the created resonating overtones on the koto for various positions on a stopped string
41.
Spectrogram
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A spectrogram is a visual representation of the spectrum of frequencies in a sound or other signal as they vary with time or some other variable. Spectrograms are sometimes called spectral waterfalls, voiceprints, or voicegrams, spectrograms can be used to identify spoken words phonetically, and to analyse the various calls of animals. They are used extensively in the development of the fields of music, sonar, radar, the frequency and amplitude axes can be either linear or logarithmic, depending on what the graph is being used for. Audio would usually be represented with a logarithmic amplitude axis, and frequency would be linear to emphasize harmonic relationships, or logarithmic to emphasize musical, tonal relationships. Spectrograms are usually created in one of two ways, approximated as a filterbank that results from a series of filters, or calculated from the time signal using the Fourier transform. These two methods actually form two different time–frequency representations, but are equivalent under some conditions, creating a spectrogram using the FFT is a digital process. Digitally sampled data, in the domain, is broken up into chunks, which usually overlap. Each chunk then corresponds to a line in the image. These spectrums or time plots are laid side by side to form the image or a three-dimensional surface, or slightly overlapped in various ways. Early analog spectrograms were applied to a range of areas including the study of bird calls, with current research continuing using modern digital equipment. Contemporary use of the spectrogram is especially useful for studying frequency modulation in animal calls. Specifically, the characteristics of FM chirps, broadband clicks. By reversing the process of producing a spectrogram, it is possible to create a signal whose spectrogram is an arbitrary image and this technique can be used to hide a picture in a piece of audio and has been employed by several electronic music artists. See Audio timescale-pitch modification and Phase vocoder, spectrograms can be used to analyze the results of passing a test signal through a signal processor such as a filter in order to check its performance. The Analysis & Resynthesis Sound Spectrograph is an example of a program that attempts to do this. The Pattern Playback was a speech synthesizer, designed at Haskins Laboratories in the late 1940s. In fact, there is some information in the spectrogram. The size and shape of the window can be varied
42.
Psychoacoustics
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Psychoacoustics is the scientific study of sound perception. More specifically, it is the branch of science studying the psychological and physiological responses associated with sound and it can be further categorized as a branch of psychophysics. Psychoacoustics received its name from a field within psychology—i. e, recognition science—which deals with all kinds of human perceptions. It is a field of many areas, including psychology, acoustics, electronic engineering, physics, biology, physiology. These nerve pulses then travel to the brain where they are perceived, the inner ear, for example, does significant signal processing in converting sound waveforms into neural stimuli, so certain differences between waveforms may be imperceptible. Data compression techniques, such as MP3, make use of this fact, in addition, the ear has a nonlinear response to sounds of different intensity levels, this nonlinear response is called loudness. Telephone networks and audio noise reduction systems make use of this fact by nonlinearly compressing data samples before transmission, another effect of the ears nonlinear response is that sounds that are close in frequency produce phantom beat notes, or intermodulation distortion products. The expression that one hears what one wants to hear may pertain in such discussions, the human ear can nominally hear sounds in the range 20 Hz to 20,000 Hz. The upper limit tends to decrease with age, most adults are unable to hear above 16 kHz, the lowest frequency that has been identified as a musical tone is 12 Hz under ideal laboratory conditions. Tones between 4 and 16 Hz can be perceived via the sense of touch. Frequency resolution of the ear is 3.6 Hz within the octave of 1000 –2000 Hz and that is, changes in pitch larger than 3.6 Hz can be perceived in a clinical setting. However, even smaller pitch differences can be perceived through other means, for example, the interference of two pitches can often be heard as a repetitive variation in volume of the tone. This amplitude modulation occurs with a equal to the difference in frequencies of the two tones and is known as beating. The semitone scale used in Western musical notation is not a frequency scale. The intensity range of sounds is enormous. Human ear drums are sensitive to variations in the sound pressure, for this reason, sound pressure level is also measured logarithmically, with all pressures referenced to 20 µPa. The lower limit of audibility is defined as 0 dB. The upper limit is more a question of the limit where the ear will be harmed or with the potential to cause noise-induced hearing loss
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Bark scale
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The Bark scale is a psychoacoustical scale proposed by Eberhard Zwicker in 1961. Above about 500 Hz this scale is more or less equal to a logarithmic frequency axis, below 500 Hz the Bark scale becomes more and more linear. The scale ranges from 1 to 24 and corresponds to the first 24 critical bands of hearing and it is related to, but somewhat less popular than, the mel scale, a perceptual scale of pitches judged by listeners to be equal in distance from one another. Since the direct measurements of the bands are subject to error. In all these phenomena, the band seems to play an important role. Thus the important attribute of the Bark scale is the width of the band at any given frequency. OR f = 600*sinh Luminosity function, which describes the average sensitivity of the eye to light of different wavelengths. Fletcher–Munson curves Equivalent rectangular bandwidth, the ERB scale Critical bands Smith and Abel - Bark and ERB Bilinear Transforms Auditory scales of frequency representation
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Combination tone
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A combination tone is a psychoacoustic phenomenon of an additional tone or tones that are artificially perceived when two real tones are sounded at the same time. Their discovery is credited to the violinist Giuseppe Tartini and so are also called Tartini tones, combination tones are heard when two pure tones, differing in frequency by about 50 cycles per second or more, sound together at sufficient intensity. Combination tones can also be produced electronically by combining two signals in a circuit that has nonlinear distortion, such as a subject to clipping or a ring modulator. One way a difference tone can be heard is when two tones with fairly complete sets of harmonics make a just fifth and this can be explained as an example of the missing fundamental phenomenon. If f is the fundamental frequency, then 2 f would be the frequency of the lower tone. Since a fifth corresponds to a ratio of 2,3. When both tones are sounded, there are components with frequencies of 2 f,3 f,4 f,6 f,8 f,9 f, the missing fundamental is heard because so many of these components refer to it. The specific phenomenon that Tartini discovered was physical, sum and difference tones are thought to be caused sometimes by the non-linearity of the inner ear. This causes intermodulation distortion of the frequencies which enter the ear. They are combined linearly, generating relatively faint components with frequencies equal to the sums and differences of whole multiples of the original frequencies. Any components which are heard are usually lower, with the most commonly heard frequency being just the tone, f 2 − f 1. However, experiments show evidence that even when using headphones providing a single pure tone to each ear separately, since the peculiar, non-linear physics of the ear doesnt come into play in this case, it is thought that this must be a separate, neural phenomenon. Heinz Bohlen proposed what is now known as the Bohlen–Pierce scale on the basis of combination tones, a resultant tone is produced when any two loud and sustained musical sounds are heard at the same time. In pipe organs, this is done by having two pipes, one pipe of the note being played, and another related, typically at its fifth. The result is a pitch at a common subharmonic of the pitches played and this effect is useful especially in the lowest ranks of the pipe organ where cost or space could prohibit having a rank of such low pitch. For example, a 64 pipe would be costly and take up at least 32 of space for each pipe, using a resultant tone for such low pitches would eliminate the cost and space factor, but would not sound as full as a true 64 pipe. This effect is most often used in the lowest octave of the organ only and it can vary from highly effective to disappointing depending on several factors, primarily the skill of the organ voicer, and the acoustics of the room the instrument is installed in. Uses combination tones for pitch recognition, if certain intervals are played in double-stop, the program can display its Tartini-tone
45.
Equal-loudness contour
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An equal-loudness contour is a measure of sound pressure, over the frequency spectrum, for which a listener perceives a constant loudness when presented with pure steady tones. The unit of measurement for loudness levels is the phon, and is arrived at by reference to equal-loudness contours, Equal-loudness contours are often referred to as Fletcher-Munson curves, after the earliest researchers, but those studies have been superseded and incorporated into newer standards. The definitive curves are defined in the international standard ISO226,2003. The human auditory system is sensitive to frequencies from about 20 Hz to a maximum of around 22,000 Hz, although the upper hearing limit decreases with age. Within this range, the ear is most sensitive between 2 and 5 kHz, largely due to the resonance of the ear canal and the transfer function of the ossicles of the middle ear. Fletcher and Munson first measured equal-loudness contours using headphones, in their study, test subjects listened to pure tones at various frequencies and over 10 dB increments in stimulus intensity. For each frequency and intensity, the listener also listened to a tone at 1000 Hz. Fletcher and Munson adjusted the reference tone until the listener perceived that it was the same loudness as the test tone, loudness, being a psychological quantity, is difficult to measure, so Fletcher and Munson averaged their results over many test subjects to derive reasonable averages. The lowest equal-loudness contour represents the quietest audible tone—the absolute threshold of hearing, the highest contour is the threshold of pain. Churcher and King carried out a second determination in 1937, but their results and Fletcher, in 1956 Robinson and Dadson produced a new experimental determination that they believed was more accurate. It became the basis for a standard that was considered definitive until 2003, perceived discrepancies between early and more recent determinations led the International Organization for Standardization to revise the standard curves in ISO226. They did this in response to recommendations in a study coordinated by the Research Institute of Electrical Communication, Tohoku University, the study produced new curves by combining the results of several studies—by researchers in Japan, Germany, Denmark, UK, and USA. This has resulted in the recent acceptance of a new set of curves standardized as ISO226,2003, Equal-loudness curves derived using headphones are valid only for the special case of what is called side-presentation, which is not how we normally hear. Real-life sounds arrive as planar wavefronts, if from a distant source. Off-centre sounds result in increased head masking at one ear, and subtle changes in the effect of the pinna and this combined effect of head-masking and pinna reflection is quantified in a set of curves in three-dimensional space referred to as head-related transfer functions. Frontal presentation is now regarded as preferable when deriving equal-loudness contours, the Robinson-Dadson determination used loudspeakers, and for a long time the difference from the Fletcher-Munson curves was explained partly on the basis that the latter used headphones. However, the ISO report actually lists the latter as using compensated headphones, good headphones, well sealed to the ear, provide a flat low-frequency pressure response to the ear canal, with low distortion even at high intensities. At low frequencies the ear is purely pressure-sensitive, and the cavity formed between headphones and ear is too small to introduce modifying resonances
