sound recording

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sound recording Conversion of sound waves into a form that can be stored and reproduced. Thomas Edison's phonograph (1877) recorded sound vibrations as indentations made by a stylus on a revolving cylinder wrapped in tinfoil. Another US inventor, German-born Emile Berliner produced a gramophone that improved the process by using a zinc disc instead of a cylinder. The volume was amplified by the addition of acoustical horns, which were replaced before World War 1 by valve amplifiers. Moulded thermoplastic records were introduced in 1901. In 1927 and 1928 patents were issued in the USA and Germany for magnetic recording processes. Later innovations include high-fidelity (hi-fi), stereophonic and quadrophonic reproduction. Modern recordings on compact disc (CD) usually employ laser-scanned digital signals.