Sound reproduction

Sound recording and reproduction is the 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.

Sound recording is the transcription of invisible vibrations in air onto a storage medium such as a phonograph disc. The process is reversed in sound reproduction, and the variations stored on the medium are transformed back into sound waves.

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.

Prior to the development of sound recording, there were mechanical systems, such as wind-up music boxes and, later, player pianos, for encoding and reproducing instrumental music.

Early history

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 they were duplicates from a master roll which had been created on a special piano, which punched holes in the master as a live performer played the song. Thus, the roll represented a recording of the actual performance of an individual, not just the more common method of punching the master roll through 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.

History of recorded sound timeline

1857 – Édouard-Léon Scott de Martinville invents the Phonautograph in Paris. Twenty years before Edison invented the recording process, Frenchman Leon Scott de Martinville invented a device for recording sound. He called it the Phonautograph and patented it on March 25, 1857. The Phonautograph recorded sound, tracing the shape of sound waves as undulations or other deviations in a line traced on smoke-blackened paper or glass, but it was not capable of playing sound back. A digitally converted phonautograph recording of ''Au Clair de la Lune '' is now considered the earliest recognizable record of the human voice and the earliest recognizable record of music.

1877 – Charles Cros invents the Paleophone. Paris was clearly the centre of the world in the early days of sound recording. It was there that Leon Scott de Martinville invented his Phonautograph to capture sound onto paper in 1857 and 20 years later Charles Cros took the process forward by working out how to record sound onto a cylinder by tracing oscillations using a screw. In April 1877 he wrote a paper describing his thesis and submitted it in a sealed envelope to the Academy of Science in Paris. Before he got a chance to build a prototype, a hard working inventor by the name of Thomas Edison living thousands of miles away in the USA beat him to it. Edison had been independently considering the same problem and in late 1877 he built a machine that recorded and played back sound which he called a Phonograph. Edison became world famous whilst Charles Cros is largely forgotten.

1878 – Thomas Edison perfects a cylinder based Phonograph that he invented the previous year. It expanded on the principles of Édouard-Léon Scott de Martinville‘s phonautograph and recorded sound onto a tinfoil sheet phonograph cylinder, and could both record and reproduce sounds. His first recording? It was the nursery rhyme “Mary’s got little lamb.”He also sets up the Edison Speaking Phonograph Company in the same year.

1880’s – Charles Sumner Tainter and Chichester Bell working under Alexander Graham Bell at his Volta Labaratory improved the phonograph cylinder including developing wax covered cardboard cylinders, ultimately creating a new form of recording machine: the Graphophone.

1887 – Emile Berliner changes the game by inventing the gramophone. Briefly based on cylinders, Berliner changed his methodology in 1888 to use discs with imprinted grooves on the flat side of a disc rather than the outside of a cylinder. He initially envisioned his invention would be a toy.

1888 – Columbia Records is born out of Alexander Graham Bell’s Volta Graphophone Company. Columbia Records named after its home state, broke away from the North American Phonograph Company selling records and phonographs manufactured by Columbia itself.

1889 – William Barry Owen and Trevor Lloyd Williams register the Gramophone Company in London. On February 23rd 1889 William Barry Owen and Trevor Lloyd Williams registered the small, private Gramophone Company. Trevor Williams was a young lawyer working in the same hotel where Owen was staying in London. American born Owen was in London with the aim of securing large amounts in funding and investment to set up The Gramophone Company in the UK, however Owen didn’t have much luck with his high profile visitors and English businessmen so in a final attempt he leant a gramophone to his lawyer – Trevor Lloyd Williams. Williams was unimpressed by the new technology at first but became convinced of the future success of The Gramophone Company after a visit to meet the gramophone inventor himself, Emile Berliner, in Washington D.C.

1898 – Magnetic recording is demonstrated in principle by Valdemar Poulsen in his Telegraphone. Poulsen obtained a Telegraphone Patent in 1898, and later developed other magnetic recorders that recorded on steel wire, tape, or disks. None of these devices had electronic amplification, but the recorded signal was strong enough to be heard through a headset or transmitted on telephone wires. In 1900 at the World Fair in Paris, Poulsen had the chance to record the voice of Emperor Franz Josef of Austria which is widely believed to be the oldest surviving magnetic audio recording.

1902 – Successful moulding processes for cylinder recordings are developed and mass production begins. Previously only several hundred sale-able cylinders could be made from each recording, so the talent was booked for marathon sessions, hours long to create as many master copies of the recording as possible.

1904 – Enrico Caruso becomes the first super star recording artist. First recorded by the Gramophone Company, Caruso went on to make over one million pounds in royalties as a result of his contacts with the Gramophone Company.

1917 – First jazz recordings are made. The Original Dixieland Jazz Band made the music’s first recordings early in 1917, and their “Livery Stable Blues” became the earliest released jazz record. The band was made up of five musicians who had previously played in the Papa Jack Laine bands, a diverse and racially integrated group of musicians who played for parades, dances, and advertising in New Orleans.

1920 – First electrical recordings are made by scientists at the Bell Laboratories in the United States. The first electrical recording issued to the public was of November 11, 1920 funeral services for the Unknown Soldier in Westminster Abbey, London. The microphones used were like those in contemporary telephones. They were inconspicuously set up in the abbey and connected by wires to recording equipment in a vehicle outside. Although electronic amplification was used, the resulting audio was weak and unclear. The novel procedure did, however, allow a recording to be made which would otherwise not have been practical in those circumstances

1925 – The invention of electrical recording allows all the major labels to start using microphones in studio sessions. The clear tone compared to acoustic recordings meant that acoustic recordings could no longer compete with their electrically recorded counter parts, so all the major labels moved over to electrical recordings.

1928 – Fritz Pfleumer develops magnetic tapes for sound recording in Germany. The tapes become widely used over the next decade with almost all studios adopting the new technology by 1935. In 1927, after experimenting with various materials, Pfleumer coated thin paper with iron oxide powder using lacquer as glue. He received a patent in 1928 for magnetic tape recording and on 1 December 1932 Pfleumer granted AEG the right to use his invention when building the world’s first practical tape recorder.

1929 – Flat discs become very popular making the cylinder obsolete and production of cylinders stops.

1931 – Alan Blumlein develops binaural sound (now known as stereo sound) at the Central Research laboratories at the EMI site in Hayes. After a night at the cinema Blumlein was frustrated that the sound from a character on screen could only be heard from a speaker at the other side of the room. To solve this problem, he invented the audio stereo system which is still in use today. He began by removing the idea that two loudspeakers represented the listeners’ two ears and instead sought to re-create the features of the sound field including directional information.

1934 – Lacquer coated discs are introduced. The introduction of lacquer-coated blank discs made instantaneous recording possible for broadcast and home recording. Very soon all the major networks began recording their programs on 16” lacquer-coated aluminum discs that could hold up to 15 minutes of audio recording on a side. Using lacquer coated discs was used well into the 1970’s when it was replaced by magnetic tape recording.

1934 – Talking Books for the blind. The American Federation for the Blind collaborated with the Library of Congress and RCA Victor records to make long playing audio books for the sight impaired. A year later the Royal institute of Blind People in London introduced their ‘Talking Books’ service.

1940 – Multi track recording developed. The guitarist, composer and technician Les Paul experimented with multi track recordings and his experiments lead to the development of 4 and 8 track recordings. These were later adopted by all the major studio’s in the 60’s with many of the Beatle’s and Rolling Stone’s Albums being the first to have 4 track records. Walt Disney’s animated feature Fantasia was one of the first commercial appearances of a four-track record, producing something similar to what is now known as surround sound.

1948 – All the major American labels introduce Vinyl records. (Shellac records are still available.)

1963 – Phillips develops the cassette tape. Their compact audio cassette was the first to combine to convenience of a tape recording format that did not require manual threading. It took about a decade before cassettes began to dominate the consumer market.

1964 – Vinyl records become the worldwide industry standard. Shellac discs are no longer produced commercially.

Phonautograph

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.

Phonograph

Thomas Edison's work on two other innovations, the telegraph and the telephone, led to the development of the phonograph. Edison was working on a machine in 1877 that would transcribe telegraphic signals onto paper tape, which could then be transferred over the telegraph again and again. The phonograph was both in a cylinder and a disc form.

Cylinder

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 by some historians as an early 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. A process for mass-producing duplicate wax cylinders by molding instead of engraving them was put into effect in 1901.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.

Disc

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 (nominally 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 which uses a conical horn connected to a diaphragm that in turn is connected to the violin bridge. The horn was no longer needed once electrical recording was developed.

The long-playing 33 rpm microgroove LP record, was developed at Columbia Records and introduced in 1948. The short-playing but convenient 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. The compact 45 format required very little material. Vinyl offered improved performance, both in stamping and in playback. 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.

Electrical

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. 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. During this time, 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 service 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, as only 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 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 artificially reduced the frequency range of recordings so they 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.

Optical and magnetic

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 photodetector to convert these variations back into an electrical signal, which was amplified and sent to loudspeakers behind the screen. 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 movie 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 synchronize 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, Kurt Stille, improved the Telegraphone with an electronic amplifier. The following year, Ludwig Blattner began work that eventually produced the Blattnerphone, which used steel tape instead of wire. The BBC
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