A dropped ceiling is a secondary ceiling, hung below the main ceiling. It may be referred to as a drop ceiling, T-bar ceiling, false ceiling, suspended ceiling, grid ceiling, drop in ceiling, drop out ceiling, or ceiling tiles and is a staple of modern construction and architecture in both residential and commercial applications. Dropped ceilings and ceiling tiles were being used in Japan for aesthetic reasons as early as the Muromachi Period. Blackfriars Theater in London, 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 and granted on October 16, 1923. Modern dropped ceilings were built using interlocking tiles and the only way to provide access for repair or inspection of the area above the tiles was by starting at the edge of the ceiling, or at a designated "key tile", removing contiguous tiles one at a time until the desired place of access was reached. Once the repair or inspection was completed, the tiles had to be reinstalled.
This process could be 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 be obtained at any desired location. Patent Number US 2,984,946 A was granted on May 23, 1961. Brown has sometimes been credited as being the inventor of the dropped ceiling though other patents preceded his as shown in the table below. Effective building design requires balancing multiple objectives: aesthetics, environmental factors, integration with the building's infrastructure—not to mention cost of construction as well as long-term operation costs. Modern dropped ceilings were created to hide the building infrastructure, including piping, and/or ductwork, by creating a plenum space above the dropped ceiling, while allowing access for repairs and inspections. Drop ceilings may be used to hide problems, such as structural damage. Further, drop out ceilings can conceal the sprinkler systems while still providing full fire suppression functionality.
For many years, dropped ceilings were made of basic white tiles, but modern innovations now offer a plethora of options in sizes, materials, visual effects and shapes and textures as well as support systems and ways to access the plenum. 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 uninviting; the acoustic performance of suspended ceilings has improved over the years, with enhanced sound absorption and attenuation. This is sometimes achieved by adding insulation known as Sound Attenuation Batts, more referred to as "sound batts", above the panels to help deaden sounds and keep adjacent rooms quieter. Indoor environmental quality includes ventilation, VOC emissions and thermal system control, thermal comfort, use of daylight for natural illumination and optimization of outdoor view availability. Many manufacturers of modern dropped.
Sustainable features may include: Energy efficiency, including daylight efficacy and thermal insulating qualities. This uses the ceiling plane to reflect daylight as well as electrical illumination to maximize lumen efficacy, which improves the comfort and usability of interior spaces. A common measure of the light reflectance of a ceiling material is ASTM E 1477 for Light Reflectance. A level of about 75 % is considered good. Reduced resources needed for construction of the tiles Recyclable/reused/renewable materials Integration with mechanical and plumbing is important with dropped ceilings, since most of these systems are by definition above the ceiling. Most ceiling system products are now designed with this integration in mind. Decisions here can affect aesthetics as well as access and maintenance. Dropped ceilings may have an improved return on investment over open ceilings A typical dropped ceiling consists of a grid-work of metal channels in the shape of an upside-down "T", suspended on wires from the overhead structure.
These channels snap together in a spaced pattern of cells. Each cell is filled with lightweight ceiling tiles or "panels" which drop into the grid; the primary grid types are "Standard 1", concealed grid. In the United States the cell size in the suspension grids is 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 suspension grids is 600×600 mm, while the ceiling tiles are smaller at 595mm x 595mm or 595mm x 1195mm. An older, less common type of dropped; this type of dropped ceiling employs a method of interlocking panels into each other and the grid with the use of small strips of metal called'splines', thus making it difficult to remove panels to gain access above the ceiling without damaging the installation or the panels. These type of ceilings will have a "key panel" which can be removed, allowing for the other panels to be slid out of the grid one by one, until removing the desired panel; this type of ceiling is more found in older installations or installations where access to above the ceiling is considered unnecessary.
A rehearsal is an activity in the performing arts that occurs as preparation for a performance in music, theatre and related arts, such as opera, musical theatre and film production. It is undertaken as a form of practising, to ensure that all details of the subsequent performance are adequately prepared and coordinated; the term "rehearsal" refers to ensemble activities undertaken by a group of people. For example, when a musician is preparing a piano concerto in their music studio, this is called "practicing", but when they practice the concerto with an orchestra, this is called a "rehearsal"; the music rehearsal takes place in a music rehearsal space. A rehearsal may involve as few as two people, as with a small play for two actors, an art song by a singer and pianist or a folk duo of a singer and guitarist. On the other end of the spectrum, a rehearsal can be held for a large orchestra with over 100 performers and a choir. A rehearsal can involve only performers of one type, as in an a cappella choir show, in which a group of singers perform without instrumental accompaniment or a play involving only theatre actors.
Rehearsals of small groups, such as small rock bands, jazz quartets or organ trios may be held without a leader. Some small groups may have their rehearsals led by a bandleader. All mid- to large-group performances have a person who leads the rehearsals. While the term is most used in the performing arts to refer to preparation for a public presentation, the term is used to refer to the preparation for other anticipated activities, such as wedding guests and couples practicing a wedding ceremony, paramedics practicing responding to a simulated emergency, or troops practicing for an attack using a mock-up of the building; the dress rehearsal is a full-scale rehearsal where the actors and/or musicians perform every detail of the performance. For a theatrical performance, cast members wear their costumes; the actors may use backdrops. For a musical performance, the dress rehearsal does not require wearing formal concert outfits. In music, the dress rehearsal is the final rehearsal before the performance.
In theatre, a performing arts ensemble rehearses a work in preparation for performance before an audience. Rehearsals that occur early in the production process are sometimes referred to as "run-throughs". A run-through does not contain many of the technical aspects of a performance, is used to assist performers in learning dialogue and to solidify aspects of blocking and stage movement. A "Q-2-Q" or "cue to cue" is a type of technical rehearsal and is intended for the lighting and audio technicians involved in a performance, although they are of great value to the entire ensemble, it is intended to allow the technicians and stage manager to rehearse the technical aspects of a performance—when lights have to be turned on, sound effects triggered, items rolled on and off the stage—and identify and resolve any glitches that might arise. Performers do not rehearse entire scenes during Q-2-Q's, but instead only perform dialogue or actions that are used by the stage manager as a marker for when to initiate technical sequences or cues.
Abbreviated Q-2-Q's in which only the opening and closing sequences of each act or scene are performed is sometimes referred to as "tops and tails". It is rare for any but the most technically complex performances to have Q-2-Q rehearsals outside of technical week. Cue to cues are preceded by a "dry tech", in which the technicians rehearse their technical cues without the actual performers present at the rehearsal. A "dress rehearsal" is a rehearsal or series of rehearsals in which the ensemble dresses in costume, as they will dress at the performance for the audience; the entire performance will be run from beginning to end as the real performances will be, including pauses for intermissions. An "open dress" is a dress rehearsal to which specific individuals have been invited to attend as audience members, they may include patrons and friends of the ensemble, or reviewers from the media. The dress rehearsal is the last set of rehearsals before the concert performance and falls at the end of technical week.
A "preview", although technically a performance as there is a full audience, including individuals who have paid for admission, is arguably a rehearsal in as far as it is not uncommon in complex performances for the production to stop, or return to an earlier point in the performance if there are unavoidable or unresolvable problems. Audience members pay a lower price to attend a preview performance. In traditional Japanese Noh theatre, performers rehearse separately, only rehearsing together once, a few days before the show; this is to emphasize the transience of the show, in the philosophy of "ichi-g
A sound baffle is a construction or device which reduces the strength of airborne sound. Sound baffles are a fundamental tool of noise mitigation, the practice of minimizing noise pollution or reverberation. An important type of sound baffle is the noise barrier constructed along highways to reduce sound levels at properties in the vicinity. Sound baffles are applied to walls and ceilings in building interiors to absorb sound energy and thus lessen reverberation; the technology for accurate prediction of the effects of noise barrier design using a computer model to analyze roadway noise has been available since the early 1970s. The earliest published scientific design of a noise barrier may have occurred in Santa Clara County, California in 1970 for a section of the Foothill Expressway in Los Altos, California; the county used a computer model to predict the effects of sound propagation from roadways, with variables consisting of vehicle speed, ratio of trucks to automobiles, road surface type, roadway geometrics, micro-meteorology and the design of proposed soundwalls.
Since the early 1900s, scientists have been aware of the utility of certain types of interior coatings or baffles to improve the acoustics of concert halls, conference rooms and other spaces where sound quality is important. By the mid-1950s, Bolt and Newman and a few other U. S. research organizations were developing technology to address sound quality's design challenges. This design field draws on several disciplines including acoustical science, computer modeling and materials science. Sound baffles are used in speaker cabinets to absorb energy from the pressure created by the speakers, thus reducing cabinet resonance. In 1973, Pearl P. Randolph, a school bus driver in Virginia, won a new school bus in a national contest held by Wayne Corporation for the suggestion that sound baffles be installed in the ceiling of school buses. In 1981, they were first made mandatory by the state of California. Baffles are found in the exhaust pipes of vehicles motorcycles. Noise pollution Noise health effects