Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording.
Acoustic analog recording is achieved by a microphone diaphragm that senses changes in atmospheric pressure caused by acoustic sound waves and records them as a mechanical representation of the sound waves on a medium such as a phonograph record (in which a stylus cuts grooves on a record). In magnetic tape recording, the sound waves vibrate the microphone diaphragm and are converted into a varying electric current, which is then converted to a varying magnetic field by an electromagnet, which makes a representation of the sound as magnetized areas on a plastic tape with a magnetic coating on it. Analog sound reproduction is the reverse process, with a bigger loudspeaker diaphragm causing changes to atmospheric pressure to form acoustic sound waves.
Digital recording and reproduction converts the analog sound signal picked up by the microphone to a digital form by the process of sampling. This lets the audio data be stored and transmitted by a wider variety of media. Digital recording stores audio as a series of binary numbers (zeros and ones) representing samples of the amplitude of the audio signal at equal time intervals, at a sample rate high enough to convey all sounds capable of being heard. A digital audio signal must be reconverted to analog form during playback before it is amplified and connected to a loudspeaker to produce sound.
Long before sound was first recorded, music was recorded—first by written music notation, then also by mechanical devices (e.g., wind-up music boxes, in which a mechanism turns a spindle, which plucks metal tines, thus reproducing a melody). Automatic music reproduction traces back as far as the 9th century, when the Banū Mūsā brothers invented the earliest known mechanical musical instrument, in this case, a hydropowered (water-powered) organ that played interchangeable cylinders. According to Charles B. Fowler, this "...cylinder with raised pins on the surface remained the basic device to produce and reproduce music mechanically until the second half of the nineteenth century." The Banū Mūsā brothers also invented an automatic flute player, which appears to have been the first programmable machine.
Carvings in the Rosslyn Chapel from the 1560s may represent an early attempt to record the Chladni patterns produced by sound in stone representations, although this theory has not been conclusively proved.
In the 14th century, a mechanical bell-ringer controlled by a rotating cylinder was introduced in Flanders. Similar designs appeared in barrel organs (15th century), musical clocks (1598), barrel pianos (1805), and music boxes (ca. 1800). A music box is an automatic musical instrument that produces sounds by the use of a set of pins placed on a revolving cylinder or disc so as to pluck the tuned teeth (or lamellae) of a steel comb.
The fairground organ, developed in 1892, used a system of accordion-folded punched cardboard books. The player piano, first demonstrated in 1876, used a punched paper scroll that could store a long piece of music. The most sophisticated of the piano rolls were hand-played, meaning that the roll represented the actual performance of an individual, not just a transcription of the sheet music. This technology to record a live performance onto a piano roll was not developed until 1904. Piano rolls were in continuous mass production from 1896 to 2008. A 1908 U.S. Supreme Court copyright case noted that, in 1902 alone, there were between 70,000 and 75,000 player pianos manufactured, and between 1,000,000 and 1,500,000 piano rolls produced.
The first device that could record actual sounds as they passed through the air (but could not play them back—the purpose was only visual study) was the phonautograph, patented in 1857 by Parisian inventor Édouard-Léon Scott de Martinville. The earliest known recordings of the human voice are phonautograph recordings, called phonautograms, made in 1857. They consist of sheets of paper with sound-wave-modulated white lines created by a vibrating stylus that cut through a coating of soot as the paper was passed under it. An 1860 phonautogram of Au Clair de la Lune, a French folk song, was played back as sound for the first time in 2008 by scanning it and using software to convert the undulating line, which graphically encoded the sound, into a corresponding digital audio file.
On April 30, 1877, French poet, humorous writer and inventor Charles Cros submitted a sealed envelope containing a letter to the Academy of Sciences in Paris fully explaining his proposed method, called the paleophone. Though no trace of a working paleophone was ever found, Cros is remembered as the earliest inventor of a sound recording and reproduction machine.
The first practical sound recording and reproduction device was the mechanical phonograph cylinder, invented by Thomas Edison in 1877 and patented in 1878. The invention soon spread across the globe and over the next two decades the commercial recording, distribution, and sale of sound recordings became a growing new international industry, with the most popular titles selling millions of units by the early 1900s. The development of mass-production techniques enabled cylinder recordings to become a major new consumer item in industrial countries and the cylinder was the main consumer format from the late 1880s until around 1910.
The next major technical development was the invention of the gramophone record, generally credited to Emile Berliner and patented in 1887, though others had demonstrated similar disk apparatus earlier, most notably Alexander Graham Bell in 1881. Discs were easier to manufacture, transport and store, and they had the additional benefit of being marginally louder than cylinders. Sales of the gramophone record overtook the cylinder ca. 1910, and by the end of World War I the disc had become the dominant commercial recording format. Edison, who was the main producer of cylinders, created the Edison Disc Record in an attempt to regain his market. The double-sided 78 rpm shellac disc was the standard consumer music format from the early 1910s to the late 1950s. In various permutations, the audio disc format became the primary medium for consumer sound recordings until the end of the 20th century.
Although there was no universally accepted speed, and various companies offered discs that played at several different speeds, the major recording companies eventually settled on a de facto industry standard of nominally 78 revolutions per minute. The specified speed was 78.26 rpm in America and 77.92 rpm throughout the rest of the world. The difference in speeds was due to the difference in the cycle frequencies of the AC electricity that powered the stroboscopes used to calibrate recording lathes and turntables. The nominal speed of the disc format gave rise to its common nickname, the "seventy-eight" (though not until other speeds had become available). Discs were made of shellac or similar brittle plastic-like materials, played with needles made from a variety of materials including mild steel, thorn, and even sapphire. Discs had a distinctly limited playing life that varied depending on how they were manufactured.
Earlier, purely acoustic methods of recording had limited sensitivity and frequency range. Mid-frequency range notes could be recorded, but very low and very high frequencies could not. Instruments such as the violin were difficult to transfer to disc. One technique to deal with this involved using a Stroh violin to which was fitted a conical horn connected to a diaphragm that vibrated due to the violin bridge. The horn was no longer needed once electrical recording was developed.
The long-playing 331⁄3 rpm microgroove vinyl record, or "LP", was developed at Columbia Records and introduced in 1948. The short-playing but convenient 7-inch (18 cm) 45 rpm microgroove vinyl single was introduced by RCA Victor in 1949. In the US and most developed countries, the two new vinyl formats completely replaced 78 rpm shellac discs by the end of the 1950s, but in some corners of the world, the "78" lingered on far into the 1960s. Vinyl was much more expensive than shellac, one of the several factors that made its use for 78 rpm records very unusual, but with a long-playing disc the added cost was acceptable and the compact "45" format required very little material. Vinyl offered improved performance, both in stamping and in playback. If played with a good diamond stylus mounted in a lightweight pickup on a well-adjusted tonearm, it was long-lasting. If protected from dust, scuffs and scratches there was very little noise. Vinyl records were, over-optimistically, advertised as "unbreakable". They were not, but they were much less fragile than shellac, which had itself once been touted as "unbreakable" compared to wax cylinders.
Between the invention of the phonograph in 1877 and the first commercial digital recordings in the early 1970s, arguably the most important milestone in the history of sound recording was the introduction of what was then called electrical recording, in which a microphone was used to convert the sound into an electrical signal that was amplified and used to actuate the recording stylus. This innovation eliminated the "horn sound" resonances characteristic of the acoustical process, produced clearer and more full-bodied recordings by greatly extending the useful range of audio frequencies, and allowed previously unrecordable distant and feeble sounds to be captured.
Sound recording began as a purely mechanical process. Except for a few crude telephone-based recording devices with no means of amplification, such as the Telegraphone, it remained so until the 1920s when several radio-related developments in electronics converged to revolutionize the recording process. These included improved microphones and auxiliary devices such as electronic filters, all dependent on electronic amplification to be of practical use in recording. In 1906, Lee De Forest invented the Audion triode vacuum tube, an electronic valve that could amplify weak electrical signals. By 1915, it was in use in long-distance telephone circuits that made conversations between New York and San Francisco practical. Refined versions of this tube were the basis of all electronic sound systems until the commercial introduction of the first transistor-based audio devices in the mid-1950s.
During World War I, engineers in the United States and Great Britain worked on ways to record and reproduce, among other things, the sound of a German U-boat for training purposes. Acoustical recording methods of the time could not reproduce the sounds accurately. The earliest results were not promising.
The first electrical recording issued to the public, with little fanfare, was of November 11, 1920 funeral services for The Unknown Warrior in Westminster Abbey, London. The recording engineers used microphones of the type used in contemporary telephones. Four were discreetly set up in the abbey and wired to recording equipment in a vehicle outside. Although electronic amplification was used, the audio was weak and unclear. The procedure did, however, produce a recording that would otherwise not have been possible in those circumstances. For several years, this little-noted disc remained the only issued electrical recording.
Several record companies and independent inventors, notably Orlando Marsh, experimented with equipment and techniques for electrical recording in the early 1920s. Marsh's electrically recorded Autograph Records were already being sold to the public in 1924, a year before the first such offerings from the major record companies, but their overall sound quality was too low to demonstrate any obvious advantage over traditional acoustical methods. Marsh's microphone technique was idiosyncratic and his work had little if any impact on the systems being developed by others.
Telephone industry giant Western Electric had research laboratories (merged with the AT&T engineering department in 1925 to form Bell Telephone Laboratories) with material and human resources that no record company or independent inventor could match. They had the best microphone, a condenser type developed there in 1916 and greatly improved in 1922, and the best amplifiers and test equipment. They had already patented an electromechanical recorder in 1918, and in the early 1920s, they decided to intensively apply their hardware and expertise to developing two state-of-the-art systems for electronically recording and reproducing sound: one that employed conventional discs and another that recorded optically on motion picture film. Their engineers pioneered the use of mechanical analogs of electrical circuits and developed a superior "rubber line" recorder for cutting the groove into the wax master in the disc recording system.
By 1924, such dramatic progress had been made that Western Electric arranged a demonstration for the two leading record companies, the Victor Talking Machine Company and the Columbia Phonograph Company. Both soon licensed the system and both made their earliest published electrical recordings in February 1925, but neither actually released them until several months later. To avoid making their existing catalogs instantly obsolete, the two long-time archrivals agreed privately not to publicize the new process until November 1925, by which time enough electrically recorded repertory would be available to meet the anticipated demand. During the next few years, the lesser record companies licensed or developed other electrical recording systems. By 1929 only the budget label Harmony was still issuing new recordings made by the old acoustical process.
Comparison of some surviving Western Electric test recordings with early commercial releases indicates that the record companies "dumbed down" the frequency range of the system so the recordings would not overwhelm non-electronic playback equipment, which reproduced very low frequencies as an unpleasant rattle and rapidly wore out discs with strongly recorded high frequencies.
In the 1920s, Phonofilm and other early motion picture sound systems employed optical recording technology, in which the audio signal was graphically recorded on photographic film. The amplitude variations comprising the signal were used to modulate a light source which was imaged onto the moving film through a narrow slit, allowing the signal to be photographed as variations in the density or width of a "sound track". The projector used a steady light and a photoelectric cell to convert these variations back into an electrical signal, which was amplified and sent to loudspeakers behind the screen. Ironically, the introduction of "talkies" was spearheaded by The Jazz Singer (1927), which used the Vitaphone sound-on-disc system rather than an optical soundtrack. Optical sound became the standard motion picture audio system throughout the world and remains so for theatrical release prints despite attempts in the 1950s to substitute magnetic soundtracks. Currently, all release prints on 35 mm film include an analog optical soundtrack, usually stereo with Dolby SR noise reduction. In addition, an optically recorded digital soundtrack in Dolby Digital and/or Sony SDDS form is likely to be present. An optically recorded timecode is also commonly included to synchronise CDROMs that contain a DTS soundtrack.
This period also saw several other historic developments including the introduction of the first practical magnetic sound recording system, the magnetic wire recorder, which was based on the work of Danish inventor Valdemar Poulsen. Magnetic wire recorders were effective, but the sound quality was poor, so between the wars, they were primarily used for voice recording and marketed as business dictating machines. In 1924, a German engineer, Dr. Kurt Stille, developed the Poulsen wire recorder as a dictating machine. The following year, Ludwig Blattner began work that eventually produced the Blattnerphone, enhancing it to use steel tape instead of wire. The BBC started using Blattnerphones in 1930 to record radio programmes. In 1933, radio pioneer Guglielmo Marconi's company purchased the rights to the Blattnerphone, and newly developed Marconi-Stille recorders were installed in the BBC's Maida Vale Studios in March 1935. The tape used in Blattnerphones and Marconi-Stille recorders was the same material used to make razor blades, and not surprisingly the fearsome Marconi-Stille recorders were considered so dangerous that technicians had to operate them from another room for safety. Because of the high recording speeds required, they used enormous reels about one metre in diameter, and the thin tape frequently broke, sending jagged lengths of razor steel flying around the studio. The K1 Magnetophon was the first practical tape recorder, developed by AEG in Germany in 1935.
An important field of invention during this period was the tape recorder. Magnetic tape recording uses an amplified electrical audio signal to generate analogous variations of the magnetic field produced by a tape head, which impresses corresponding variations of magnetization on the moving tape. In playback mode, the signal path is reversed, the tape head acting as a miniature electric generator as the varyingly magnetized tape passes over it. The original solid steel ribbon was replaced by a much more practical coated paper tape, but acetate soon replaced paper as the standard tape base. Acetate has fairly low tensile strength and if very thin it will snap easily, so it was in turn eventually superseded by polyester. This technology, the basis for almost all commercial recording from the 1950s to the 1980s, was developed in the 1930s by German audio engineers who also rediscovered the principle of AC biasing (first used in the 1920s for wire recorders), which dramatically improved the frequency response of tape recordings. The technology was further improved just after World War II by American audio engineer John T. Mullin with backing from Bing Crosby Enterprises. Mullin's pioneering recorders were modifications of captured German recorders. In the late 1940s, the Ampex company produced the first tape recorders commercially available in the US.
Magnetic tape brought about sweeping changes in both radio and the recording industry. Sound could be recorded, erased and re-recorded on the same tape many times, sounds could be duplicated from tape to tape with only minor loss of quality, and recordings could now be very precisely edited by physically cutting the tape and rejoining it. Within a few years of the introduction of the first commercial tape recorder—the Ampex 200 model, launched in 1948—American musician-inventor Les Paul had invented the first multitrack tape recorder, ushering in another technical revolution in the recording industry. Tape made possible the first sound recordings totally created by electronic means, opening the way for the bold sonic experiments of the Musique Concrète school and avant garde composers like Karlheinz Stockhausen, which in turn led to the innovative pop music recordings of artists such as Frank Zappa, The Beatles, and The Beach Boys.
The ease and accuracy of tape editing, as compared to the cumbersome disc-to-disc editing procedures previously in some limited use, together with tape's consistently high audio quality finally convinced radio networks to routinely prerecord their entertainment programming, most of which had formerly been broadcast live. Also, for the first time, broadcasters, regulators and other interested parties were able to undertake comprehensive audio logging of each day's radio broadcasts. Innovations like multitracking and tape echo allowed radio programs and advertisements to be produced to a high level of complexity and sophistication. The combined impact with innovations such as the endless loop broadcast cartridge led to significant changes in the pacing and production style of radio program content and advertising.
In 1881, it was noted during experiments in transmitting sound from the Paris Opera that it was possible to follow the movement of singers on the stage if earpieces connected to different microphones were held to the two ears. This discovery was commercialized in 1890 with the Théâtrophone system, which operated for over forty years until 1932. In 1931, Alan Blumlein, a British electronics engineer working for EMI, designed a way to make the sound of an actor in a film follow his movement across the screen. In December 1931, he submitted a patent including the idea, and in 1933 this became UK patent number 394,325. Over the next two years, Blumlein developed stereo microphones and a stereo disc-cutting head, and recorded a number of short films with stereo soundtracks.
In the 1930s, experiments with magnetic tape enabled the development of the first practical commercial sound systems that could record and reproduce high-fidelity stereophonic sound. The experiments with stereo during the 1930s and 1940s were hampered by problems with synchronization. A major breakthrough in practical stereo sound was made by Bell Laboratories, who in 1937 demonstrated a practical system of two-channel stereo, using dual optical sound tracks on film. Major movie studios quickly developed three-track and four-track sound systems, and the first stereo sound recording for a commercial film was made by Judy Garland for the MGM movie Listen, Darling in 1938. The first commercially released movie with a stereo soundtrack was Walt Disney's Fantasia, released in 1940. The 1941 release of Fantasia used the "Fantasound" sound system. This system used a separate film for the sound, synchronized with the film carrying the picture. The sound film had four double-width optical soundtracks, three for left, center, and right audio—and a fourth as a "control" track with three recorded tones that controlled the playback volume of the three audio channels. Because of the complex equipment this system required, Disney exhibited the movie as a roadshow, and only in the United States. Regular releases of the movie used standard mono optical 35 mm stock until 1956, when Disney released the film with a stereo soundtrack that used the "Cinemascope" four-track magnetic sound system.
German audio engineers working on magnetic tape developed stereo recording by 1941, even though a 2-track push-pull monaural technique existed in 1939. Of 250 stereophonic recordings made during WW2, only three survive: Beethoven's 5th Piano Concerto with Walter Gieseking and Arthur Rother, a Brahms Serenade, and the last movement of Bruckner's 8th Symphony with Von Karajan. The Audio Engineering Society has issued all these recordings on CD. (Varèse Sarabande had released the Beethoven Concerto on LP, and it has been reissued on CD several times since). Other early German stereophonic tapes are believed to have been destroyed in bombings. Not until Ampex introduced the first commercial two-track tape recorders in the late 1940s did stereo tape recording become commercially feasible. However, despite the availability of multitrack tape, stereo did not become the standard system for commercial music recording for some years, and remained a specialist market during the 1950s. EMI (UK) was the first company to release commercial stereophonic tapes. They issued their first Stereosonic tape in 1954. Others quickly followed, under the His Master's Voice and Columbia labels. 161 Stereosonic tapes were released, mostly classical music or lyric recordings. RCA imported these tapes into the USA.
Two-track stereophonic tapes were more successful in America during the second half of the 1950s. They were duplicated at real time (1:1) or at twice the normal speed (2:1) when later 4-track tapes were often duplicated at up to 16 times the normal speed, providing a lower sound quality in many cases. Early American 2-track stereophonic tapes were very expensive. A typical example is the price list of the Sonotape/Westminster reels: $6.95, $11.95 and $17.95 for the 7000, 9000 and 8000 series respectively. Some HMV tapes released in the USA also cost up to $15. The history of stereo recording changed after the late 1957 introduction of the Westrex stereo phonograph disc, which used the groove format developed earlier by Blumlein. Decca Records in England came out with FFRR (Full Frequency Range Recording) in the 1940s, which became internationally accepted as a worldwide standard for higher quality recording on vinyl records. The Ernest Ansermet recording of Igor Stravinsky's Petrushka was key in the development of full frequency range records and alerting the listening public to high fidelity in 1946.
Record companies mixed most popular music singles into monophonic sound until the mid-1960s—then commonly released major recordings in both mono and stereo until the early 1970s. Many 1960s pop albums available only in stereo in the 2000s were originally released only in mono, and record companies produced the "stereo" versions of these albums by simply separating the two tracks of the master tape, creating "pseudo stereo". In the mid Sixties, as stereo became more popular, many mono recordings (such as The Beach Boys' Pet Sounds) were remastered using the so-called "fake stereo" method, which spread the sound across the stereo field by directing higher-frequency sound into one channel and lower-frequency sounds into the other.
Magnetic tape transformed the recording industry. By the early 1950s, most commercial recordings were mastered on tape instead of recorded directly to disc. Tape facilitated a degree of manipulation in the recording process that was impractical with mixes and multiple generations of directly recorded discs. An early example is Les Paul's 1951 recording of How High the Moon, on which Paul played eight overdubbed guitar tracks. In the 1960s Brian Wilson of The Beach Boys, Frank Zappa, and The Beatles (with producer George Martin) were among the first popular artists to explore the possibilities of multitrack recording techniques and effects on their landmark albums Pet Sounds, Freak Out!, and Sgt. Pepper's Lonely Hearts Club Band.
The next important innovation was small cartridge-based tape systems, of which the compact cassette, commercialized by the Philips electronics company in 1964, is the best known. Initially a low-fidelity format for spoken-word voice recording and inadequate for music reproduction, after a series of improvements it entirely replaced the competing formats: the larger 8-track tape (used primarily in cars) and the fairly similar "Deutsche Cassette" developed by the German company Grundig. This latter system was not particularly common in Europe and practically unheard-of in America. The compact cassette became a major consumer audio format and advances in electronic and mechanical miniaturization led to the development of the Sony Walkman, a pocket-sized cassette player introduced in 1979. The Walkman was the first personal music player and it gave a major boost to sales of prerecorded cassettes, which became the first widely successful release format that used a re-recordable medium: the vinyl record was a playback-only medium and commercially prerecorded tapes for reel-to-reel tape decks, which many consumers found difficult to operate, were never more than an uncommon niche market item.
A key advance in audio fidelity came with the Dolby A noise reduction system, invented by Ray Dolby and introduced into professional recording studios in 1966. It suppressed the light but sometimes quite noticeable steady background of hiss, which was the only easily audible downside of mastering on tape instead of recording directly to disc. A competing system, dbx, invented by David Blackmer, also found success in professional audio. A simpler variant of Dolby's noise reduction system, known as Dolby B, greatly improved the sound of cassette tape recordings by reducing the especially high level of hiss that resulted from the cassette's miniaturized tape format. It, and variants, also eventually found wide application in the recording and film industries. Dolby B was crucial to the popularization and commercial success of the cassette as a domestic recording and playback medium, and it became a standard feature in the booming home and car stereo market of the 1970s and beyond. The compact cassette format also benefited enormously from improvements to the tape itself as coatings with wider frequency responses and lower inherent noise were developed, often based on cobalt and chrome oxides as the magnetic material instead of the more usual iron oxide.
The multitrack audio cartridge had been in wide use in the radio industry, from the late 1950s to the 1980s, but in the 1960s the pre-recorded 8-track cartridge was launched as a consumer audio format by Bill Lear of the Lear Jet aircraft company (and although its correct name was the 'Lear Jet Cartridge', it was seldom referred to as such). Aimed particularly at the automotive market, they were the first practical, affordable car hi-fi systems, and could produce sound quality superior to that of the compact cassette. However the smaller size and greater durability — augmented by the ability to create home-recorded music "compilations" since 8-track recorders were rare — saw the cassette become the dominant consumer format for portable audio devices in the 1970s and 1980s.
There had been experiments with multi-channel sound for many years — usually for special musical or cultural events — but the first commercial application of the concept came in the early 1970s with the introduction of Quadraphonic sound. This spin-off development from multitrack recording used four tracks (instead of the two used in stereo) and four speakers to create a 360-degree audio field around the listener. Following the release of the first consumer 4-channel hi-fi systems, a number of popular albums were released in one of the competing four-channel formats; among the best known are Mike Oldfield's Tubular Bells and Pink Floyd's The Dark Side of the Moon. Quadraphonic sound was not a commercial success, partly because of competing and somewhat incompatible four-channel sound systems (e.g., CBS, JVC, Dynaco and others all had systems) and generally poor quality, even when played as intended on the correct equipment, of the released music. It eventually faded out in the late 1970s, although this early venture paved the way for the eventual introduction of domestic Surround Sound systems in home theatre use, which have gained enormous popularity since the introduction of the DVD. This widespread adoption has occurred despite the confusion introduced by the multitude of available surround sound standards.
The replacement of the relatively fragile thermionic valve (vacuum tube) by the smaller, lighter-weight, cooler-running, less expensive, more robust, and less power-hungry transistor also accelerated the sale of consumer high-fidelity "hi-fi" sound systems from the 1960s onward. In the 1950s, most record players were monophonic and had relatively low sound quality. Few consumers could afford high-quality stereophonic sound systems. In the 1960s, American manufacturers introduced a new generation of "modular" hi-fi components — separate turntables, pre-amplifiers, amplifiers, both combined as integrated amplifiers, tape recorders, and other ancillary equipment like the graphic equaliser, which could be connected together to create a complete home sound system. These developments were rapidly taken up by major Japanese electronics companies, which soon flooded the world market with relatively affordable, high-quality transistorized audio components. By the 1980s, corporations like Sony had become world leaders in the music recording and playback industry.
The advent of digital sound recording and later the compact disc (CD) in 1982 brought significant improvements in the durability of consumer recordings. The CD initiated another massive wave of change in the consumer music industry, with vinyl records effectively relegated to a small niche market by the mid-1990s. However, the record industry fiercely resisted the introduction of digital systems, fearing wholesale piracy on a medium able to produce perfect copies of original released recordings. However, the industry succumbed to the inevitable, though using various protection system (principally Serial Copy Management System, or SCMS).
The most recent and revolutionary developments have been in digital recording, with the development of various uncompressed and compressed digital audio file formats, processors capable and fast enough to convert the digital data to sound in real time, and inexpensive mass storage . This generated new types of portable digital audio players. The minidisc player, using ATRAC compression on small, cheap, re-writeable discs was introduced in the 1990s but became obsolescent as solid-state non-volatile flash memory dropped in price. As technologies that increase the amount of data that can be stored on a single medium, such as Super Audio CD, DVD-A, Blu-ray Disc, and HD DVD become available, longer programs of higher quality fit onto a single disc. Sound files are readily downloaded from the Internet and other sources, and copied onto computers and digital audio players. Digital audio technology is now used in all areas of audio, from casual use of music files of moderate quality to the most demanding professional applications. New applications such as internet radio and podcasting have appeared.
Technological developments in recording, editing, and consuming have transformed the record, movie and television industries in recent decades. Audio editing became practicable with the invention of magnetic tape recording, but digital audio and cheap mass storage allows computers to edit audio files quickly, easily, and cheaply. Today, the process of making a recording is separated into tracking, mixing and mastering. Multitrack recording makes it possible to capture signals from several microphones, or from different takes to tape, disc or mass storage, with maximized headroom and quality, allowing previously unavailable flexibility in the mixing and mastering stages.
There are many different digital audio recording and processing programs running under several computer operating systems for all purposes, ranging from casual users (e.g., a small business person recording her "to-do" list on an inexpensive digital recorder) to serious amateurs (an unsigned "indie" band recording their demo on a laptop) to professional sound engineers who are recording albums, film scores and doing sound design for video games. A comprehensive list of digital recording applications is available at the digital audio workstation article. Digital dictation software for recording and transcribing speech has different requirements; intelligibility and flexible playback facilities are priorities, while a wide frequency range and high audio quality are not.
The development of analog sound recording in the nineteenth century and its widespread use throughout the twentieth century had a huge impact on the development of music. Before analog sound recording was invented, most music was listened to by hearing a live performance, or by singing or playing a song or piece. Throughout the medieval, Renaissance, Baroque, Classical, and through much of the Romantic music era, the main way that songs and instrumental pieces were "recorded" was by notating the piece in music notation. While music notation indicates the pitches of the melody and their rhythm, the notation is not like a 2010-era sound recording. Indeed, in the Medieval era, Gregorian chant did not indicate the rhythm of the chant. In the Baroque era, instrumental pieces often lack a tempo indication and usually none of the ornaments were written down. As a result, each performance of a song or piece would be slightly different.
With the development of analog sound recording, though, a performance could be permanently fixed, in all of its elements: pitch, rhythm, timbre, ornaments and expression. This meant that many more elements of a performance would be captured and disseminated to other listeners. The development of sound recording also enabled a much larger proportion of people to hear famous orchestras, operas, singers and bands, because even if a non-wealthy person could not afford to hear the live concert, she or he might be able to afford to buy the recording. The availability of sound recording thus helped to spread musical styles to new regions, countries and continents. The cultural influence went in a number of directions. Sound recordings enabled Western music lovers to hear actual recordings of Asian, Middle Eastern and African groups and performers, increasing awareness of non-Western musical styles. At the same time, sound recordings enabled non-Western music lovers to hear the most famous North American and European groups and singers.
In copyright law, a "phonogram" or "sound recording" is a work that results from the fixation of sounds in a medium. The notice of copyright in a phonogram uses the sound recording copyright symbol, which the Geneva Phonograms Convention defines as ℗ (the letter P in a full circle). This usually accompanies the copyright notice for the underlying musical composition, which uses the ordinary © symbol.
United States copyright law defines "sound recordings" as "works that result from the fixation of a series of musical, spoken, or other sounds" other than an audiovisual work's soundtrack. Prior to the Sound Recording Amendment (SRA), which took effect in 1972, copyright in sound recordings was handled at the level of the several states. Federal copyright law preempts most state copyright laws but allows state copyright in sound recordings to continue for one full copyright term after the SRA's effective date, which means 2067.
Since 1934, copyright law in Great Britain has treated sound recordings (or phonograms) differently from musical works. Copyright, Designs and Patents Act 1988 defines a sound recording as (a) a recording of sounds, from which the sounds may be reproduced, or (b) a recording of the whole or any part of a literary, dramatic or musical work, from which sounds reproducing the work or part may be produced, regardless of the medium on which the recording is made or the method by which the sounds are reproduced or produced. It thus covers vinyl records, tapes, compact discs, digital audiotapes, and MP3s that embody recordings.
Keynote address was presented to the 104th Convention of the Audio Engineering Society in Amsterdam during the society's golden anniversary celebration on May 17, 1998.
Aleksander Kolkowski (born 1959 in London) is a British musician and composer whose work combines instruments and machines from the pioneering era of sound recording and reproduction (Stroh violins, wind-up Gramophones, shellac discs and wax-cylinder Phonographs) to make live mechanical-acoustic music. He lives and works in London, England.Audio equipment
Audio equipment refers to devices that reproduce, record, or process sound. This includes microphones, radio receivers, AV receivers, CD players, tape recorders, amplifiers, mixing consoles, effects units, and loudspeakers.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. These tracks that are blended together are done so by using various processes such as equalization and compression. Audio mixing techniques and approaches can vary widely, and due to the skill-level or intent of the mixer, can greatly affect the qualities of the sound recording.Audio mixing techniques largely depend on music genres and the quality of sound recordings involved. The process is generally 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 a mixing console or digital audio workstation.Comparison of free software for audio
This list of free software for audio lists notable free and open source software for use by sound engineers, audio producers, and those involved in sound recording and reproduction.Digital audio
Digital audio is sound that has been recorded in, or converted into, digital form. In digital audio, the sound wave of the audio signal is encoded as numerical samples in continuous sequence. For example, in CD audio, samples are taken 44100 times per second each with 16 bit sample depth. Digital audio is also the name for the entire technology of sound recording and reproduction using audio signals that have been encoded in digital form. Following significant advances in digital audio technology during the 1970s, it gradually replaced analog audio technology in many areas of audio engineering and telecommunications in the 1990s and 2000s.
In a digital audio system, an analog electrical signal representing the sound is converted with an analog-to-digital converter (ADC) into a digital signal, typically using pulse-code modulation. This digital signal can then be recorded, edited, modified, and copied using computers, audio playback machines, and other digital tools. When the sound engineer wishes to listen to the recording on headphones or loudspeakers (or when a consumer wishes to listen to a digital sound file), a digital-to-analog converter (DAC) performs the reverse process, converting a digital signal back into an analog signal, which is then sent through an audio power amplifier and ultimately to a loudspeaker.
Digital audio systems may include compression, storage, processing, and transmission components. Conversion to a digital format allows convenient manipulation, storage, transmission, and retrieval of an audio signal. Unlike analog audio, in which making copies of a recording results in generation loss and degradation of signal quality, digital audio allows an infinite number of copies to be made without any degradation of signal quality.Equalization (audio)
Equalization or equalisation is the process of adjusting the balance between frequency components within an electronic signal. The most well known use of equalization is in sound recording and reproduction but there are many other applications in electronics and telecommunications. The circuit or equipment used to achieve equalization is called an equalizer. These devices strengthen (boost) or weaken (cut) the energy of specific frequency bands or "frequency ranges".
In sound recording and reproduction, equalization is the process commonly used to alter the frequency response of an audio system using linear filters. Most hi-fi equipment uses relatively simple filters to make bass and treble adjustments. Graphic and parametric equalizers have much more flexibility in tailoring the frequency content of an audio signal. Since equalizers "adjust the amplitude of audio signals at particular frequencies," they are, "in other words, frequency-specific volume knobs."In the field of audio electronics, the term "equalization" (or "EQ") has come to include the adjustment of frequency responses for practical or aesthetic reasons, often resulting in a net response that is not actually "flat". The term EQ specifically refers to this variant of the term. Stereos and basic guitar amplifiers typically have adjustable equalizers which boost or cut bass or treble frequencies. Mid- to high-priced guitar and bass amplifiers usually have more bands of frequency control, such as bass, mid-range and treble or bass, low-mid, high-mid, and treble. Some amps have an additional knob for controlling very high frequencies. Broadcast and recording studios use sophisticated equalizers capable of much more detailed adjustments, such as eliminating unwanted sounds or making certain instruments or voices more prominent.
Equalizers are used in recording studios, radio studios and production control rooms, and live sound reinforcement and in instrument amplifiers, such as guitar amplifiers, to correct or adjust the response of microphones, instrument pick-ups, loudspeakers, and hall acoustics. Equalization may also be used to eliminate or reduce unwanted sounds (e.g., low hum coming from a guitar amplifier), make certain instruments or voices more (or less) prominent, enhance particular aspects of an instrument's tone, or combat feedback (howling) in a public address system. Equalizers are also used in music production to adjust the timbre of individual instruments and voices by adjusting their frequency content and to fit individual instruments within the overall frequency spectrum of the mix.The most common equalizers in music production are parametric, semi-parametric, graphic, peak, and program equalizers. Graphic equalizers are often included in consumer audio equipment and software which plays music on home computers. Parametric equalizers require more expertise than graphic equalizers, and they can provide more specific compensation or alteration around a chosen frequency. This may be used in order to remove unwanted resonances or boost certain frequencies. For example, an acoustic guitarist who finds that her instrument sounds too "boomy" may ask the audio engineer to cut the low frequencies to correct this issue; or a guitarist who finds that the amplified instrument sound has too much finger noise may ask the engineer to reduce the high frequencies.Eventide, Inc
Eventide, Inc. (also known earlier as Eventide Clock Works Inc., or today simply Eventide) is an audio, broadcast and communications company in the United States whose audio division manufactures digital audio processors and DSP software, and guitar effects. Eventide was one of the first companies to manufacture digital audio processors, and its products are mainstays in sound recording and reproduction, post production, and broadcast studios.Filmmaking
Filmmaking (or, in an academic context, film production) is the process of making a film, generally in the sense of films intended for extensive theatrical exhibition. Filmmaking involves a number of discrete stages including an initial story, idea, or commission, through screenwriting, casting, shooting, sound recording and reproduction, editing, and screening the finished product before an audience that may result in a film release and exhibition. Filmmaking takes place in many places around the world in a range of economic, social, and political contexts, and using a variety of technologies and cinematic techniques. Typically, it involves a large number of people, and can take from a few months to several years to complete.Ground lift
In sound recording and reproduction, ground lift or earth lift is a technique used to reduce or eliminate ground-related noise arising from ground loops in audio cables. It may also increase or decrease noise from other sources. Activating the ground lift on a particular piece of equipment opens the connection between the equipment ground and the shielding conductor of audio cables attached to the equipment, leaving those cables grounded only at their opposite end.
If all pieces of equipment are tied to a common ground reference without establishing ground loop, no current flows in the ground conductors and cable shields, and no noise is introduced into signal circuits. In applications such as sound reinforcement for a concert, however, it is difficult to ensure all equipment shares a common ground reference.Imaging
Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of an image).Magnetic tape
Magnetic tape is a medium for magnetic recording, made of a thin, magnetizable coating on a long, narrow strip of plastic film. It was developed in Germany in 1928, based on magnetic wire recording. Devices that record and play back audio and video using magnetic tape are tape recorders and video tape recorders respectively. A device that stores computer data on magnetic tape is known as a tape drive.
Magnetic tape revolutionized sound recording and reproduction and broadcasting. It allowed radio, which had always been broadcast live, to be recorded for later or repeated airing. It allowed gramophone records to be recorded in multiple parts, which were then mixed and edited with tolerable loss in quality. It was a key technology in early computer development, allowing unparalleled amounts of data to be mechanically created, stored for long periods, and rapidly accessed.
In recent decades, other technologies have been developed that can perform the functions of magnetic tape. In many cases, these technologies have replaced tape. Despite this, innovation in the technology continues, and Sony and IBM continue to produce new magnetic tape drives.Over time, magnetic tape made in the 1970s and 1980s can suffer from a type of deterioration called sticky-shed syndrome. It is caused by hydrolysis of the binder in the tape and can render the tape unusable.Music technology (electric)
Electric music technology refers to musical instruments and recording devices that use electrical circuits, which are often combined with mechanical technologies. Examples of electric musical instruments include the electro-mechanical electric piano (invented in 1929), the electric guitar (invented in 1931), the electro-mechanical Hammond organ (developed in 1934) and the electric bass (invented in 1935). All of these electric instruments do not produce a sound that is audible by the performer or audience in a performance setting unless they are connected to instrument amplifiers and loudspeaker cabinets, which made them sound loud enough for performers and the audience to hear. Amplifiers and loudspeakers are separate from the instrument in the case of the electric guitar (which uses a guitar amplifier), electric bass (which uses a bass amplifier) and some electric organs (which use a Leslie speaker or similar cabinet) and most electric pianos. Some electric organs and electric pianos include the amplifier and speaker cabinet within the main housing for the instrument.
Electric sound recording and reproduction are electrical or mechanical techniques and devices for the inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. Acoustic analog recording is achieved by a small microphone diaphragm that can record sound waves on a phonograph (in which a stylus senses grooves on a record) or magnetic tape. The first practical sound recording and reproduction device was the mechanical phonograph cylinder, invented by Thomas Edison in 1877 and patented in 1878.
The next major technical development was the invention of the gramophone disc in 1889. For much of the 20th century, records were the most common way of selling sound recordings. The widespread availability of records and the development of radio broadcasting enabled a much larger proportion of people to listen to songs and pieces performed by the top artists, enabling the development of national and even international musical stars. In the 1970s, the compact cassette became a major consumer audio format. Advances in electronic and mechanical miniaturization led to the development of the Sony Walkman, a pocket-sized cassette player introduced in 1979, which allowed consumers to listen to their favourite albums outside of their home.SPARS code
The SPARS code is a three-position alphabetic classification system developed in the early 1980s by the Society of Professional Audio Recording Services (SPARS) for commercial compact disc releases to denote aspects of the sound recording and reproduction process, distinguishing between the use of analog equipment and digital equipment. The code's three positions refer to recording, mixing, and mastering respectively. The first two positions may be coded either "A" for analog or "D" for digital; the third position (mastering) is always "D" on digital CDs. The scheme was not originally intended to be limited to use on digital packaged media: it was also available for use in conjunction with analog releases such as vinyl or cassette (where the final character would be "A"), but this was never done in practice.
The system was first implemented in 1984. Due to increasing complexity of recording and mixing processes developed over the code's first decade of use, SPARS decided to withdraw endorsement of the code in 1991 because they felt the code was overly simplistic and did not accurately reflect the complexity of typical recording and mixing processes in use at the time. However, many record labels continued to use the code and SPARS decided to re-endorse the SPARS code in 1995.Sound design
Sound design is the art and practice of creating sound tracks for a variety of needs. It involves specifying, acquiring or creating auditory elements using audio production techniques and tools. It is employed in a variety of disciplines including filmmaking, television production, video game development, theatre, sound recording and reproduction, live performance, sound art, post-production, radio and musical instrument development. Sound design commonly involves performing (see e.g. foley) and editing of previously composed or recorded audio, such as sound effects and dialogue for the purposes of the medium. A sound designer is one who practices sound design.Stereo imaging
Stereo imaging refers to the aspect of sound recording and reproduction concerning the perceived spatial locations of the sound source(s), both laterally and in depth. An image is considered to be good if the location of the performers can be clearly located; the image is considered to be poor if the location of the performers is difficult to locate. A well-made stereo recording, properly reproduced, can provide good imaging within the front quadrant; a well-made Ambisonic recording, properly reproduced, can offer good imaging all around the listener and even including height information.
For many listeners, good imaging adds markedly to the pleasure of reproduced music. One may speculate that this is due to the evolutionary importance to humans of knowing where sounds are coming from, and that imaging may therefore be more important than some purely aesthetic considerations in satisfying the listener.
The quality of the imaging arriving at the listener's ear depends on numerous factors, of which the most important is the original "miking", that is, the choice and arrangement of the recording microphones (where "choice" refers here not to the brands chosen, but to the size and shape of the microphone diaphragms, and "arrangement" refers to microphone placement and orientation relative to other microphones). This is partly because miking simply affects imaging more than any other factor, and because, if the miking spoils the imaging, nothing later in the chain can recover it.
If miking is done well, then quality of imaging can be used to evaluate components in the record/playback chain (remembering that once the imaging is destroyed, it cannot be recovered).
Only a handful of recordings are miked for optimal imaging, and what usually passes for stereo, while being two-channel recording, is not true stereo because the imaging information is incoherent.Imaging is usually thought of in the context of recording with two or more channels, though single-channel recording may convey depth information convincingly.Timeline of audio formats
An audio format is a medium for sound recording and reproduction. The term is applied to both the physical recording media and the recording formats of the audio content—in computer science it is often limited to the audio file format, but its wider use usually refers to the physical method used to store the data.
Music is recorded and distributed using a variety of audio formats, some of which store additional information.Valve audio amplifier
A valve audio amplifier (UK) or vacuum tube audio amplifier (United States) is a valve amplifier used for sound reinforcement, sound recording and reproduction.
Until the invention of solid state devices such as the transistor, all electronic amplification was produced by valve (tube) amplifiers. While solid-state devices prevail in most audio amplifiers today, valve audio amplifiers are still used where their audible characteristics are considered pleasing, for example in music performance or music reproduction.
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