Recording

Analog Sound Recording

Sound recording refers to the ability to convert acoustical energy (the vibrations of air molecules) into a preservable form for storage and distribution; this converted energy can be mechanical (i.e., the bumps in the groove of a vinyl record) or magnetic (i.e., polarized particles on magnetic tape). The resulting recorded forms in “analog” media, such as vinyl records and recording tape, are analogous to the original sound vibrations. Digital sound media, such as CDs, MP3 players, and the Internet, on the other hand, use a binary numerical representation of analog waveform measurements to manipulate and preserve a mathematical equivalent of sound vibrations. These digital representations are converted to analog acoustical energy when played back.

Thomas Edison is usually credited with inventing the first practical device capable of recording the human voice. Speaking the words of a simple nursery rhyme, “Mary had a little lamb,” Edison launched sound recording history. His hand crank driven tinfoil cylinder “phonograph” (a Greek word for “sound writer”), patented in 1878, converted sound vibrations into corresponding indentations in a spiral groove pattern on a cylinder. Among other applications, Edison thought the phonograph could be used for dictation; for educational purposes; to record speeches, books, and music; to make toys, clocks, and music boxes; and to preserve lasting records of telegraph and telephone messages.

An image of Edison's early phonograph equipment photographed in his lab in 1892.

Source: Library of Congress.

Major improvements to the phonograph soon followed. Working with Alexander Graham Bell in 1886, Chichester Bell (Alexander's cousin) and Charles Tainter developed the “grapho-phone,” a wax cylinder machine that increased the number of times a cylinder could be played. Emile Berliner's hard shellac flat disc system, [Page 1187]called the “gramophone,” improved sound quality and made both duplication and storage more convenient. In 1929, Berliner sold his patent and “His Master's Voice” logo (a painting showing a dog “Nipper” cocking his head by the horn speaker of a phonograph) to the Victor Talking Machine Company, which later became a division of the Radio Corporation of America. Improved methods of molding cylinders and discs for mass duplication, spring (wind-up) and electric motor drive systems, and significant accomplishments in radio electronics, contributed to developments in microphone, amplifier and loudspeaker technologies. Although an effort was made to market the phonograph as an office dictation machine, consumers adopted these early systems for home entertainment and music recording. RCA Victor became a major producer of phonograph records and the company's “Victrola” players became a prominent piece of furniture in many homes. In 1929, RCA introduced a 16-inch diameter transcription disc, made from “Vitrolac.” This recordable “electronic transcription” (ET) disc system enabled radio stations to record and playback music and talk programs.

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