The guitar is a fretted musical instrument that has six strings. It is played with both hands by strumming or plucking the strings with either a guitar pick or the finger/fingernails of one hand, while fretting with the fingers of the other hand; the sound of the vibrating strings is projected either acoustically, by means of the hollow chamber of the guitar, or through an electrical amplifier and a speaker. The guitar is a type of chordophone, traditionally constructed from wood and strung with either gut, nylon or steel strings and distinguished from other chordophones by its construction and tuning; the modern guitar was preceded by the gittern, the vihuela, the four-course Renaissance guitar, the five-course baroque guitar, all of which contributed to the development of the modern six-string instrument. There are three main types of modern acoustic guitar: the classical guitar, the steel-string acoustic guitar, the archtop guitar, sometimes called a "jazz guitar"; the tone of an acoustic guitar is produced by the strings' vibration, amplified by the hollow body of the guitar, which acts as a resonating chamber.
The classical guitar is played as a solo instrument using a comprehensive finger-picking technique where each string is plucked individually by the player's fingers, as opposed to being strummed. The term "finger-picking" can refer to a specific tradition of folk, blues and country guitar playing in the United States; the acoustic bass guitar is a low-pitched instrument, one octave below a regular guitar. Electric guitars, introduced in the 1930s, use an amplifier and a loudspeaker that both makes the sound of the instrument loud enough for the performers and audience to hear, given that it produces an electric signal when played, that can electronically manipulate and shape the tone using an equalizer and a huge variety of electronic effects units, the most used ones being distortion and reverb. Early amplified guitars employed a hollow body, but solid wood guitars began to dominate during the 1960s and 1970s, as they are less prone to unwanted acoustic feedback "howls"; as with acoustic guitars, there are a number of types of electric guitars, including hollowbody guitars, archtop guitars and solid-body guitars, which are used in rock music.
The loud, amplified sound and sonic power of the electric guitar played through a guitar amp has played a key role in the development of blues and rock music, both as an accompaniment instrument and performing guitar solos, in many rock subgenres, notably heavy metal music and punk rock. The electric guitar has had a major influence on popular culture; the guitar is used in a wide variety of musical genres worldwide. It is recognized as a primary instrument in genres such as blues, country, folk, jota, metal, reggae, rock and many forms of pop. Before the development of the electric guitar and the use of synthetic materials, a guitar was defined as being an instrument having "a long, fretted neck, flat wooden soundboard, a flat back, most with incurved sides." The term is used to refer to a number of chordophones that were developed and used across Europe, beginning in the 12th century and in the Americas. A 3,300-year-old stone carving of a Hittite bard playing a stringed instrument is the oldest iconographic representation of a chordophone and clay plaques from Babylonia show people playing an instrument that has a strong resemblance to the guitar, indicating a possible Babylonian origin for the guitar.
The modern word guitar, its antecedents, has been applied to a wide variety of chordophones since classical times and as such causes confusion. The English word guitar, the German Gitarre, the French guitare were all adopted from the Spanish guitarra, which comes from the Andalusian Arabic قيثارة and the Latin cithara, which in turn came from the Ancient Greek κιθάρα. Which comes from the Persian word "sihtar"; this pattern of naming is visible in setar and sitar. The word "tar" at the end of all of these words is a Persian word that means "string". Many influences are cited as antecedents to the modern guitar. Although the development of the earliest "guitars" is lost in the history of medieval Spain, two instruments are cited as their most influential predecessors, the European lute and its cousin, the four-string oud. At least two instruments called "guitars" were in use in Spain by 1200: the guitarra latina and the so-called guitarra morisca; the guitarra morisca had a rounded back, wide fingerboard, several sound holes.
The guitarra Latina had a narrower neck. By the 14th century the qualifiers "moresca" or "morisca" and "latina" had been dropped, these two cordophones were referred to as guitars; the Spanish vihuela, called in Italian the "viola da mano", a guitar-like instrument of the 15th and 16th centuries, is considered to have been the single most important influence in the development of the baroque guitar. It had six courses, lute-like tuning in fourths and a guitar-like body, although early representations reveal an instrument with a cut waist, it was larger than the contemporary four-course guitars. By the 16th century, the vihuela's construction had more in common with the modern guitar, with its curved one-piece ribs, than with the viols, more like a larger version of the contemporary four-course guita
Charles Hardin Holley, known as Buddy Holly, was an American musician, singer-songwriter and record producer, a central and pioneering figure of mid-1950s rock and roll. He was born in Lubbock, Texas, to a musical family during the Great Depression, learned to play guitar and sing alongside his siblings, his style was influenced by gospel music, country music, rhythm and blues acts, he performed in Lubbock with his friends from high school. He made his first appearance on local television in 1952, the following year he formed the group "Buddy and Bob" with his friend Bob Montgomery. In 1955, after opening for Elvis Presley, he decided to pursue a career in music, he opened for Presley three times that year. In October that year, when he opened for Bill Haley & His Comets, he was spotted by Nashville scout Eddie Crandall, who helped him get a contract with Decca Records. Holly's recording sessions at Decca were produced by Owen Bradley, who had become famous for producing orchestrated country hits for stars like Patsy Cline.
Unhappy with Bradley's musical style and control in the studio, Holly went to producer Norman Petty in Clovis, New Mexico, recorded a demo of "That'll Be the Day", among other songs. Petty became the band's manager and sent the demo to Brunswick Records, which released it as a single credited to "The Crickets", which became the name of Holly's band. In September 1957, as the band toured, "That'll Be the Day" topped the UK singles charts, its success was followed in October by another major hit, "Peggy Sue". The album Chirping Crickets, released in November 1957, reached number five on the UK Albums Chart. Holly made his second appearance on The Ed Sullivan Show in January 1958 and soon after, toured Australia and the UK. In early 1959, he assembled a new band, consisting of future country music star Waylon Jennings, famed session musician Tommy Allsup, Carl Bunch, embarked on a tour of the midwestern U. S. After a show in Clear Lake, Iowa, he chartered an airplane to travel to his next show, in Moorhead, Minnesota.
Soon after takeoff, the plane crashed, killing Holly, Ritchie Valens, The Big Bopper, pilot Roger Peterson in a tragedy referred to by Don McLean as "The Day the Music Died". During his short career, Holly wrote and produced his own material, he is regarded as the artist who defined the traditional rock-and-roll lineup of two guitars and drums. He was a major influence on popular music artists, including Bob Dylan, The Beatles, The Rolling Stones, Eric Clapton, Elton John, he was among the first artists inducted into the Rock and Roll Hall of Fame, in 1986. Rolling Stone magazine ranked him number 13 in its list of "100 Greatest Artists". Holly was born Charles Hardin Holley on September 7, 1936, in Texas. O." Holley and Ella Pauline Drake. His elder siblings were Larry and Patricia Lou. Buddy Holly was of English and Welsh descent but had small amounts of Native American ancestry as well. From early childhood, he was nicknamed "Buddy". During the Great Depression, the Holleys moved residence within Lubbock.
O. changed jobs several times. Buddy Holly was baptized a Baptist, the family were members of the Tabernacle Baptist Church; the Holleys had an interest in music. O. were able to sing. The elder Holley brothers performed in local talent shows. Since he could not play it, his brother Larry greased the strings; the brothers won the contest. During World War II, Larry and Travis were called to military service. Upon his return, Larry brought with him a guitar he had bought from a shipmate while serving in the Pacific. At age 11, Buddy abandoned them after nine months, he switched to the guitar after he saw a classmate singing on the school bus. Buddy's parents bought him a steel guitar, but he insisted that he wanted a guitar like his brother's, his parents bought the guitar from a pawnshop, Travis taught him to play it. During his early childhood, Holley was influenced by the music of Hank Williams, Jimmie Rodgers, Hank Snow, Bob Wills, the Carter Family. At Roscoe Wilson Elementary, he became friends with Bob Montgomery, the two played together, practicing with songs by the Louvin Brothers and Johnnie & Jack.
They both listened to the radio programs Grand Ole Opry on WSM, Louisiana Hayride on KWKH, Big D Jamboree. At the same time, Holley played with other musicians he met in high school, including Sonny Curtis and Jerry Allison. In 1952, Holley and Jack Neal participated as a duo billed as "Buddy and Jack" in a talent contest on a local television show. After Neal left, he was replaced by Montgomery and they were billed as "Buddy and Bob"; the two soon started performing on the Sunday Party show on KDAV in 1953 and performed live gigs in Lubbock. At that time, Holley was influenced by late-night radio stations that played blues and rhythm and blues. Holley would sit in his car with Curtis and tune to distant radio stations that could only be received at night, when local transmissions ceased. Holley modified his music by blending his earlier country and western influence with R & B. By 1955, after graduating from high school, Holley decided to pursue a full-time career in music, he was further encouraged after seeing Elvis Presley performing live in Lubbock, whose act was booked by Pappy Dave Stone of KDAV.
In February, Holley opened for Presley at the Fair Park Coliseum
Robert Michael Nesmith is an American musician, actor, novelist and philanthropist, best known as a member of the pop rock band the Monkees and co-star of the TV series The Monkees. Nesmith's songwriting credits include "Different Drum". After the break-up of the Monkees, Nesmith continued his successful songwriting and performing career, first with the seminal country rock group the First National Band, with whom he had a top-40 hit, "Joanne", as a solo artist, he is a noted player of the 12-string guitar, performing on custom-built 12-string electric guitars with the Monkees and various 12-string acoustic models during his post-Monkees career. He is an executive producer of the cult film Repo Man. In 1981, Nesmith won the first Grammy Award given for Video of the Year for his hour-long television show, Elephant Parts. Nesmith was born in Houston, Texas, in 1942, he is an only child. He and his mother moved to Dallas to be closer to her family. Bette took temporary jobs ranging from clerical work to graphic design.
When Nesmith was 13, his mother invented the typewriter correction fluid known commercially as Liquid Paper. Over the next 25 years, she built the Liquid Paper Corporation into a multimillion-dollar international company, which she sold to Gillette in 1979 for US$48 million, she died a few months aged 56. Nesmith participated in drama activities at Thomas Jefferson High School in Dallas, he began to write verse poetry. At 15, he was in the Dallas Theater Center teen program. Without graduating from high school, Nesmith enlisted in the United States Air Force in 1960, he completed basic training at Lackland Air Force Base in San Antonio, was trained as an aircraft mechanic at Sheppard Air Force Base in Wichita Falls and was permanently stationed at the Clinton-Sherman Air Force Base near Burns Flat, Oklahoma. While in the Air Force, Nesmith obtained a GED and was discharged under honorable conditions in 1962, he enrolled in San Antonio College, a community college, where he met John Kuehne and began a musical collaboration.
The duo won the first San Antonio College talent award, performing a mixture of standard folk songs and a few of Nesmith's original songs. While in college, Nesmith began to write more songs and poetry and after moving to Los Angeles, began singing in folk clubs around the city, he served as the "Hootmaster" for the Monday night hootenannies at The Troubadour, a West Hollywood nightclub that featured new artists. Nesmith performed with many different members of the burgeoning new LA music scene. Randy Sparks from the New Christy Minstrels offered Nesmith a publishing deal for his songs, it was during this time that Barry Friedman, aka the Rev. Frazier Mohawk, showed him an ad for auditions for a new TV series, The Monkees. In October 1965, Nesmith landed the role as the wool hat-wearing guitar player "Mike" in the show, which required real-life musical talent; the Monkees television series aired from 1966 until 1968, has developed a cult following over the years. After a tour of duty in the Air Force, Nesmith was given a guitar as a Christmas present from his mother and stepfather.
Learning as he went, he played solo and in a series of working bands, performing folk and rock and roll. His verse poems became the basis for song lyrics, after moving to Los Angeles with Phyllis and friend John London, he signed a publishing deal for his songs. Nesmith's "Mary, Mary" was recorded by the Paul Butterfield Blues Band, while "Different Drum" and "Some of Shelly's Blues" were recorded by Linda Ronstadt and the Stone Poneys. "Pretty Little Princess", written in 1965, was recorded by Frankie Laine and released as a single in 1968 on ABC Records. "Some of Shelly's Blues" and "Propinquity" were made popular by the Nitty Gritty Dirt Band on their 1970 album Uncle Charlie & His Dog Teddy. Nesmith began his recording career in 1963 by releasing a single on the Highness label, he followed this in 1965 with a one-off single released on Edan Records followed by two more recorded singles. From 1965 to early 1970, Nesmith was a member of the television pop-rock band The Monkees, created for the television situation comedy of the same name.
Nesmith won his role by appearing nonchalant when he auditioned. He rode his motorcycle to the audition, wore a wool hat to keep his hair out of his eyes. Once he was cast, Screen Gems bought his songs. Many of the songs Nesmith wrote for The Monkees, such as "The Girl I Knew Somewhere", "Mary, Mary", "Listen to the Band", became minor hits. One song he wrote, "You Just May Be the One", is in mixed meter, interspersing 5/4 bars into an otherwise 4/4 structure; as part of a promotional deal, Gretsch guitar company built a one-off, natural-finish, 12-string electric guitar for Nesmith when he was performing with The Monkees. The custom-made guitar was cited at that time as being worth $5,000, undoubtedly inflated for publicity purposes, he earlier played a customized Gretsch 12-string, a six-str
Ampex is an American electronics company founded in 1944 by Alexander M. Poniatoff as a spin-off of Dalmo-Victor; the name AMPEX is a portmanteau, created by its founder, which stands for Alexander M. Poniatoff Excellence. Today, Ampex operates as Ampex Data Systems Corporation, a subsidiary of Delta Information Systems, consists of two business units; the Silicon Valley unit, known internally as Ampex Data Systems, manufactures ruggedized, high-capacity, high-performance digital data storage systems capable of functioning in harsh environments on land, in the air, at sea, in space. The Colorado Springs, Colorado unit, referred to as Ampex Intelligent Systems, serves as a laboratory and hub for the company’s line of industrial control system cyber security products and services and its artificial intelligence/machine learning technology, available across all of the company’s products. Ampex's first great success was a line of reel-to-reel tape recorders developed from the German wartime Magnetophon system at the behest of Bing Crosby.
Ampex became a leader in audio tape technology, developing many of the analog recording formats for both music and movies that remained in use into the 1990s. Starting in the 1950s, the company began developing video tape recorders, introduced the helical scan concept that make home video players possible, they introduced multi-track recording, slow-motion and instant playback television, a host of other advances. Ampex's tape business was rendered obsolete during the 1990s, the company turned to digital storage products. Ampex moved into digital storage for DoD Flight Test Instrumentation with the introduction of the first, true all digital flight test recorder. Ampex supports numerous major DoD programs with the US Air Force, US Army, US Marines, US Navy and other government entities. Ampex works with all major DoD primes and integrators including Boeing, General Atomics, Northrop and many others; the new Ampex is attempting to do more with the data stored on its network attached storage devices.
This includes adding advanced encryption for more secure data storage. Russian-American inventor Alexander Matthew Poniatoff established the company in San Carlos, California, in 1944 as the Ampex Electric and Manufacturing Company; the company name came from his initials plus "ex" to avoid using the name AMP in use. During World War II, Ampex was a subcontractor to Dalmo-Victor, manufacturing high quality electric motors and generators for radars that used alnico 5 magnets from General Electric. Ampex was setup in abandoned loft-space above the Dalmo-Victor plant. Near the end of the war, while serving in the U. S. Army Signal Corps, Major Jack Mullin was assigned to investigate German radio and electronics experiments, he discovered the Magnetophons with AC biasing on a trip to Radio Frankfurt. The device produced much better fidelity than shellac records; the technological processes in tape recording and equipment developed by German companies before and during the 1939-45 War had copyrights which were voided after Germany's 1945 surrender and defeat.
Mullin acquired two Magnetophon recorders and 50 reels of BASF Type L tape, brought them to America, where he produced modified versions. He demonstrated them to the Institute of Radio Engineers in San Francisco on May 16, 1946. Bing Crosby, a big star on radio at the time, was receptive to the idea of pre-recording his radio programs, he disliked the regimentation of live broadcasts, much preferred the relaxed atmosphere of the recording studio. He had asked the NBC network to let him pre-record his 1944-45 series on transcription discs, but the network refused, so Crosby had withdrawn from live radio for a year and returned for the 1946-47 season only reluctantly. Another possible motivation wasn't so much that Crosby wanted the more relaxed atmosphere of taping vs live but that live network radio required performing two identical shows a night, one for the east coast and one for the west coast; this may have been what Crosby was hoping to avoid, as, the argument Crosby used with the radio network when he asked to use transcription disc recordings of his show.
Those recordings were made directly from the live east coast show, as were the taped versions. In June 1947, pitching the technology to the major Hollywood movie studios, got the chance to demonstrate his modified tape recorders to Crosby; when Crosby heard a demonstration of Mullin's tape recorders, he saw the potential of the new technology and commissioned Mullin to prepare a test recording of his radio show. Ampex was finishing its prototype of the Model 200 tape recorder and Mullin used the first two models as soon as they were built. After a successful test broadcast, ABC agreed to allow Crosby to pre-record his shows on tape. Crosby appointed Mullin as his chief engineer and placed an order for $50,000 worth of the new recorders so that Ampex could develop a commercial production model from the prototypes. Crosby Enterprises was Ampex's West Coast representative until 1957; the company's first tape recorder, the Ampex Model 200, was first shipped in April 1948. The first two units, serial numbers 1 and 2, were used to record the Bing Crosby Show.
The American Broadcasting Company used these recorders alon
Audio mixing (recorded music)
In sound recording and reproduction, audio mixing is the process of combining multitrack recordings into a final mono, stereo or surround sound product. In the process of combining the separate tracks, their relative levels are adjusted and balanced and various processes such as equalization and compression are applied to individual tracks, groups of tracks, the overall mix. In stereo and surround sound mixing, the placement of the tracks within the stereo field are adjusted and balanced. Audio mixing techniques and approaches vary and have a significant influence on the final product. Audio mixing techniques depend on music genres and the quality of sound recordings involved; the process is carried out by a mixing engineer, though sometimes the record producer or recording artist may assist. After mixing, a mastering engineer prepares the final product for production. Audio mixing may be performed on digital audio workstation. In the late 19th century, Thomas Edison and Emile Berliner developed the first recording machines.
The recording and reproduction process itself was mechanical with little or no electrical parts. Edison's phonograph cylinder system utilized a small horn terminated in a stretched, flexible diaphragm attached to a stylus which cut a groove of varying depth into the malleable tin foil of the cylinder. Emile Berliner's gramophone system recorded music by inscribing spiraling lateral cuts onto a vinyl disc. Electronic recording became more used during the 1920s, it was based on the principles of electromagnetic transduction. The possibility for a microphone to be connected remotely to a recording machine meant that microphones could be positioned in more suitable places; the process was improved when outputs of the microphones could be mixed before being fed to the disc cutter, allowing greater flexibility in the balance. Before the introduction of multitrack recording, all sounds and effects that were to be part of a record were mixed at one time during a live performance. If the recorded mix wasn't satisfactory, or if one musician made a mistake, the selection had to be performed over until the desired balance and performance was obtained.
With the introduction of multi-track recording, the production of a modern recording changed into one that involves three stages: recording and mixing. Modern mixing emerged with the introduction of commercial multi-track tape machines, most notably when 8-track recorders were introduced during the 1960s; the ability to record sounds into separate channels meant that combining and treating these sounds could be postponed to the mixing stage. In the 1980s, home recording and mixing became more efficient; the 4-track Portastudio was introduced in 1979. Bruce Springsteen released the album Nebraska in 1982 using one; the Eurythmics topped the charts in 1983 with the song "Sweet Dreams", recorded by band member Dave Stewart on a makeshift 8-track recorder. In the mid-to-late 1990s, computers replaced tape-based recording for most home studios, with the Power Macintosh proving popular. At the same time, digital audio workstations, first used in the mid-1980s, began to replace tape in many professional recording studios.
A mixer is the operational heart of the mixing process. Mixers offer a multitude of inputs, each fed by a track from a multitrack recorder. Mixers have 2 main outputs or 8. Mixers offer three main functionalities. Summing signals together, done by a dedicated summing amplifier or, in the case of a digital mixer, by a simple algorithm. Routing of source signals to external processing units and effects. On-board processors with equalizers and compressors. Mixing consoles can be intimidating due to the exceptional number of controls. However, because many of these controls are duplicated, much of the console can be learned by studying one small part of it; the controls on a mixing console will fall into one of two categories: processing and configuration. Processing controls are used to manipulate the sound; these can vary in complexity, from simple level controls, to sophisticated outboard reverberation units. Configuration controls deal with the signal routing from the input to the output of the console through the various processes.
Digital audio workstations can perform many mixing features in addition to other processing. An audio control surface gives a DAW the same user interface as a mixing console; the distinction between a large console and a DAW equipped with a control surface is that a digital console will consist of dedicated digital signal processors for each channel. DAWs can dynamically assign resources like digital audio signal processing power, but may run out if too many signal processes are in simultaneous use; this overload can be solved by increasing the capacity of the DAW. Outboard gear and software plugins can be inserted into the signal path to extend processing possibilities. Outboard gear and plugins fall into two main categories: Processors – these devices are connected in series to the signal path, so the input signal is replaced with the processed signal. Examples include dynamic processing. However, some processors are used in parallel, as is the case in techniques such as parallel compression/limiting and sidechain equalization.
Effects – these can be considered as any unit that has an effect upon the signal, the term is used to describe units that are connected in parallel to the sig
A microphone, colloquially nicknamed mic or mike, is a transducer that converts sound into an electrical signal. Microphones are used in many applications such as telephones, hearing aids, public address systems for concert halls and public events, motion picture production and recorded audio engineering, sound recording, two-way radios, megaphones and television broadcasting, in computers for recording voice, speech recognition, VoIP, for non-acoustic purposes such as ultrasonic sensors or knock sensors. Several different types of microphone are in use, which employ different methods to convert the air pressure variations of a sound wave to an electrical signal; the most common are the dynamic microphone. Microphones need to be connected to a preamplifier before the signal can be recorded or reproduced. In order to speak to larger groups of people, a need arose to increase the volume of the human voice; the earliest devices used to achieve this were acoustic megaphones. Some of the first examples, from fifth century BC Greece, were theater masks with horn-shaped mouth openings that acoustically amplified the voice of actors in amphitheatres.
In 1665, the English physicist Robert Hooke was the first to experiment with a medium other than air with the invention of the "lovers' telephone" made of stretched wire with a cup attached at each end. In 1861, German inventor Johann Philipp Reis built an early sound transmitter that used a metallic strip attached to a vibrating membrane that would produce intermittent current. Better results were achieved in 1876 with the "liquid transmitter" design in early telephones from Alexander Graham Bell and Elisha Gray – the diaphragm was attached to a conductive rod in an acid solution; these systems, gave a poor sound quality. The first microphone that enabled proper voice telephony was the carbon microphone; this was independently developed by David Edward Hughes in England and Emile Berliner and Thomas Edison in the US. Although Edison was awarded the first patent in mid-1877, Hughes had demonstrated his working device in front of many witnesses some years earlier, most historians credit him with its invention.
The carbon microphone is the direct prototype of today's microphones and was critical in the development of telephony and the recording industries. Thomas Edison refined the carbon microphone into his carbon-button transmitter of 1886; this microphone was employed at the first radio broadcast, a performance at the New York Metropolitan Opera House in 1910. In 1916, E. C. Wente of Western Electric developed the next breakthrough with the first condenser microphone. In 1923, the first practical moving coil microphone was built; the Marconi-Sykes magnetophone, developed by Captain H. J. Round, became the standard for BBC studios in London; this was improved in 1930 by Alan Blumlein and Herbert Holman who released the HB1A and was the best standard of the day. In 1923, the ribbon microphone was introduced, another electromagnetic type, believed to have been developed by Harry F. Olson, who reverse-engineered a ribbon speaker. Over the years these microphones were developed by several companies, most notably RCA that made large advancements in pattern control, to give the microphone directionality.
With television and film technology booming there was demand for high fidelity microphones and greater directionality. Electro-Voice responded with their Academy Award-winning shotgun microphone in 1963. During the second half of 20th century development advanced with the Shure Brothers bringing out the SM58 and SM57; the latest research developments include the use of fibre optics and interferometers. The sensitive transducer element of a microphone is called its capsule. Sound is first converted to mechanical motion by means of a diaphragm, the motion of, converted to an electrical signal. A complete microphone includes a housing, some means of bringing the signal from the element to other equipment, an electronic circuit to adapt the output of the capsule to the equipment being driven. A wireless microphone contains a radio transmitter. Microphones are categorized by their transducer principle, such as condenser, etc. and by their directional characteristics. Sometimes other characteristics such as diaphragm size, intended use or orientation of the principal sound input to the principal axis of the microphone are used to describe the microphone.
The condenser microphone, invented at Western Electric in 1916 by E. C. Wente, is called a capacitor microphone or electrostatic microphone—capacitors were called condensers. Here, the diaphragm acts as one plate of a capacitor, the vibrations produce changes in the distance between the plates. There are two types, depending on the method of extracting the audio signal from the transducer: DC-biased microphones, radio frequency or high frequency condenser microphones. With a DC-biased microphone, the plates are biased with a fixed charge; the voltage maintained across the capacitor plates changes with the vibrations in the air, according to the capacitance equation, where Q = charge in coulombs, C = capacitance in farads and V = potential difference in volts. The capacitance of the plates is inversely proportional to the distance between them for a parallel-plate capacitor; the assembly of fixed and movable plates is called an "element" or "capsule". A nearly constant charge is maintained on the capa
A choir is a musical ensemble of singers. Choral music, in turn, is the music written for such an ensemble to perform. Choirs may perform music from the classical music repertoire, which spans from the medieval era to the present, or popular music repertoire. Most choirs are led by a conductor, who leads the performances with face gestures. A body of singers who perform together as a group is called a chorus; the former term is often applied to groups affiliated with a church and the second to groups that perform in theatres or concert halls, but this distinction is far from rigid. Choirs may sing without instrumental accompaniment, with the accompaniment of a piano or pipe organ, with a small ensemble, or with a full orchestra of 70 to 100 musicians; the term "Choir" has the secondary definition of a subset of an ensemble. In typical 18th- to 21st-century oratorios and masses, chorus or choir is understood to imply more than one singer per part, in contrast to the quartet of soloists featured in these works.
Choirs are led by a conductor or choirmaster. Most choirs consist of four sections intended to sing in four part harmony, but there is no limit to the number of possible parts as long as there is a singer available to sing the part: Thomas Tallis wrote a 40-part motet entitled Spem in alium, for eight choirs of five parts each. Other than four, the most common number of parts are three, five and eight. Choirs can sing without instrumental accompaniment. Singing without accompaniment is called a cappella singing. Accompanying instruments vary from only one instrument to a full orchestra of 70 to 100 musicians. Many choirs perform in many locations such as a church, opera house, or school hall. In some cases choirs join up to become one "mass" choir. In this case they provide a series of songs or musical works to celebrate and provide entertainment to others. Conducting is the art of directing a musical performance, such as a choral concert, by way of visible gestures with the hands, arms and head.
The primary duties of the conductor or choirmaster are to unify performers, set the tempo, execute clear preparations and beats, to listen critically and shape the sound of the ensemble. The conductor or choral director stands on a raised platform and he or she may or may not use a baton. In the 2010s, most conductors do not play an instrument when conducting, although in earlier periods of classical music history, leading an ensemble while playing an instrument was common. In Baroque music from the 1600s to the 1750s, conductors performing in the 2010s may lead an ensemble while playing a harpsichord or the violin. Conducting while playing a piano may be done with musical theatre pit orchestras. Communication is non-verbal during a performance. However, in rehearsals, the conductor will give verbal instructions to the ensemble, since they also serve as an artistic director who crafts the ensemble's interpretation of the music. Conductors act as guides to the choirs they conduct, they choose the works to be performed and study their scores, to which they may make certain adjustments, work out their interpretation, relay their vision to the singers.
Choral conductors may have to conduct instrumental ensembles such as orchestras if the choir is singing a piece for choir and orchestra. They may attend to organizational matters, such as scheduling rehearsals, planning a concert season, hearing auditions, promoting their ensemble in the media. Eastern Orthodox churches, some American Protestant groups, traditional synagogues do not use instruments. In churches of the Western Rite the accompanying instrument is the organ, although in colonial America, the Moravian Church used groups of strings and winds. Many churches which use a contemporary worship format use a small amplified band to accompany the singing, Roman Catholic Churches may use, at their discretion, additional orchestral accompaniment. In addition to leading of singing in which the congregation participates, such as hymns and service music, some church choirs sing full liturgies, including propers. Chief among these are the Roman Catholic churches. Mixed choirs; this is the most common type consisting of soprano, alto and bass voices abbreviate