Digital Music

Background

The history of digital music parallels the history of computing. Harry Nyquist's 1929 publication of what is known as Nyquist's Theorem was a key initial development; it proved that periodic “snapshots” or “samples” of a sound could be taken, and that the sounds could be reconstructed later using those snapshots. Nyquist further demonstrated that if sounds are sampled at a rate at least twice as fast as their original frequency, no sound quality is lost upon reconstruction. Nyquist's Theorem, published before the invention of digital computers, is now the foundation for all digital-audio processing. In 1937, an International Telephone and Telegraph electrical engineer, Alec H. Reeves, advanced Nyquist's idea by devising pulse code modulation (PCM), a technology that digitizes sounds by [Page 144]sampling them 8,000 times a second. PCM still is used in most forms of digital recording.

Two decades would pass before Max Mathews, head of behavioral sciences research at Bell Labs and an amateur violinist, generated the first digital music from a computer in 1957. Mathews' work with digital signal processing (DSP) helped push analog telecommunications into the digital realm, while also helping to inaugurate modern digital music.

In 1979, the Royal Philips Electronics firm developed a prototype for the CD, a five-inch-diameter plastic disk with many tiny pockets pressed into it. A song's digital code is “burned” into these dimples on the disk's surface using laser technology, storing the song for later playback. At the end of the 1970s, Philips and Sony of Japan entered an agreement to jointly produce a commercially viable version of the CD, and by 1980 they arrived at a standard that gave CDs 650 MB (megabytes) of data storage, about 74 minutes of music. By 1983, electronics companies began rolling out CD players, and by 1988, Philips alone was manufacturing three million players a year. Record stores around the world began tearing out their album racks to give CDs more retail space.

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