The introduction of compact disc players, devices for playing digitally encoded music, created a new level of sound quality and rejuvenated the music industry.
Ever since Thomas Alva Edison invented the phonograph in 1876, people have been captivated by the ability to hear popular music in their homes. A steady string of improvements followed, and when affordable mass-produced flat disc records became available in the first half of the twentieth century, the recording industry entered the American mainstream. The introduction of magnetic tape recorders, stereo, and cassette tapes in the decades after World War II created an even larger market. As the technologies associated with the audio industry improved, however, new recording mediums became a priority. When the Japanese electronics giants who supplied much of the audio equipment began to look for a replacement recording medium in the 1960’s, they turned to digital audio.
Traditional sound recording had been done in analog, a continuous waveform (CW). The analog pattern of a song was encoded on the record, and the record player and receiver turned this information back into recognizable sound. Digital recording was more complicated, yet yielded better results. In digital recording, instantaneous samples of an analog wave are taken at set intervals, and the information is then stored as binary code (the representation of traditional numerical quantities in base 2, or a system of 0’s and 1’s). Binary coding had been used for some time in the computer industry and thus, technologically, the story of digital audio roughly parallels that of the computer. Theoretically, however, digital audio had been anticipated for some time.
The earliest form this took was in the work of the French mathematician Joseph Fourier. Fourier’s theorem stated that discrete samples taken of a continuous waveform could reproduce the original waveform exactly, given that enough samples were taken. An example of what Fourier meant can be shown given a simple sine wave. The analog method of recording the wave would be to record every point along the wave. The digital method of recording, as outlined in Fourier’s theorem, would be to take readings of value, in this case, the amplitude of the wave, at regular intervals. Fourier said that from these discrete samples, one could reproduce the wave exactly, with no loss of information (or in this instance, sound). It was not until 1928, however, that anyone developed a formula for telling how many samples one needed to take to be able to use Fourier’s theorem.
Among the important products made possible by compact disc technology are CD-ROM drives that enable computer users to access large volumes of program software, sound and image files, and other information from compact and inexpensive disks.
At a meeting of the American Institute of Electrical Engineers, a physicist with Bell Laboratories
Nyquist, however, certainly never envisioned the compact disc when he derived his theorem. The technological realities were still far in the future. Theoretical developments that would be utilized later continued to be made. The most important of these was the 1948 work of another Bell Laboratories researcher, the mathematician Claude Elwood Shannon. In a paper titled “A Mathematical Theory of Communication,” Shannon outlined an entirely new science information theory. He said that communications lines carried units of information that could be measured, transmitted, and tested. The terms of binary coding explained the new theory. Information theory explained how noise in the form of random errors could corrupt the flow of information, now measured in bits (a unit of value 0 or 1), and it suggested ways in which this random error could be reduced or even eliminated. The error-correction codes that would find their way into compact disc encoding were developed in 1960 by two Massachusetts Institute of Technology researchers, Irving S. Reed
Several technological breakthroughs were still needed before the compact disc player could become more than a dream. Developments in the computer industry, coupled with the development of the transistor and later the integrated circuit, or microchip, made optical data storage possible. The development of a working laser in 1960 meant that research into optical storage could begin. By the late 1960’s, the Japanese firms NHK Technical Research Institute and Sony Corporation
The technical problems of a laser-read optical disc were solved and solved for the low-cost consumer market in 1978, when several companies, led by Philips’s Magnavox
By the end of the 1970’s, there were at least nine separate prototype digital audio systems. Still stung from the format wars associated with both the videodisc and the videocassette, two of the largest players, Philips and Sony, agreed in 1979 to work together to produce a standard format. By acting together and licensing the basic technology, thirty-five electronics manufacturers officially adopted the Philips/Sony standard in 1980. Two years later, in 1982, the compact disc player was introduced into Japanese and European markets, followed in 1983 by that of the United States.
The features of the compact disc (CD) readily showed their difference from the standard analog LPs. The CD was much smaller than the LP; it measured 12 centimeters in diameter, was thinner at only 1.2 millimeters, and weighed only about 14 grams. Its composition was different as well. The CD had a base composed of a type of hard Plexiglas, into which the information was pressed. On top of that came a reflective layer of aluminum or silver, and on top of that a protective layer of acrylic resin, onto which the labeling could be screened.
The information was stored in the form of “pits” sunk into the base material. Although all the pits were the same width, they differed in length, as did the plain regions between them. Each pit and plain represented one binary number value, which contained not only the original sound but also the error-checking and error-correcting schemes. The information was read when the tightly focused low-intensity laser passed over the spiral track of pits and plains, with each diffracting the light differently. The differing diffraction patterns were then translated into binary. Finally, a converter changed the binary information back into an analog waveform. Digital audio had arrived.
The immediate impact of the CD and the CD player was not overly spectacular. The plans for digital audio disc technology had been publicly known for several years before its introduction. In fact, were it not for a recession, the CD player could have been introduced a year earlier. Second, there was debate about whether the new medium was actually as good as it was billed. Some claimed that it brought with it its own kind of distortion; others claimed that it lacked the “warmth” of the analog recordings. Perhaps the greatest reason that the CD player failed to leap immediately into the limelight, however, was the lack of CDs to play in them. When the players were introduced, there were only two manufacturing plants for CDs in the world: one in Hanover, West Germany, and another in Japan.
Within a short period of time, however, the situation had changed. New manufacturing plants, including one in Terre Haute, Indiana, greatly increased the number and variety of available CDs. Listeners were generally impressed with the quality of the sound. The price of individual CDs, initially somewhat high, came down steadily. Their size made them easier to use and store, and their near indestructibility and promise of a long lifetime offered an end to the need to replace worn or damaged records.
Although it was not evident at first, the introduction of the CD standard was the deathblow for the LP. With retailers unwilling to support three standards for long, the CD’s success meant that fewer and fewer LPs would be released. By the end of the 1980’s, LPs, which had earlier slipped behind sales of cassette tapes, were reduced to a trickle. Many new albums were not even released in an LP version. Even the nationwide Record Bar retail chain made plans to change its name.
Sales of both players and discs steadily increased. In the first year after their introduction, 30,000 CD players were sold in the United States alone, accompanied by 800,000 discs. By 1984, 230,000 players had been sold. By 1986, the figure was 3 million.
New technologies, however, made CDs a bit precarious. Digital audiotape (DAT) was developed to be to the traditional cassette what CD was to the LP, but DAT proved a commercial failure. CD-ROM, a first cousin of the CD that stored electronic data, was introduced in 1984, and plans for other types of CD mediums for the computer were developed. With the introduction of CD-burning capabilities, and later the Internet, music lovers could easily make their own copies of musical favorites by downloading music and burning CD recordings. The introduction of the iPod by Apple Corporation in 2001 made it possible to download, store, and replay large numbers of recordings on a small portable device. CD technology succeeded in opening up new paths for both the electronics industry and the consumer and guaranteed that, while nothing ever stays the same, it would at least sound that way.
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Millman, S., ed. A History of Engineering and Science in the Bell System: Communications Sciences, 1925-1980. New York: AT&T Bell Laboratories, 1984. A house history written by the technical staff. Nothing on compact discs, but excellent coverage of the work of Nyquist and Shannon. Semipopular, but difficult. Excellent references. Photographs, illustrations, index. -
Pohlmann, Ken C. The Compact Disc: A Handbook of Theory and Use. Madison, Wis.: A-R Editions, 1989. A good introduction to the topic. Somewhat technical. Good historical section, with some minor errors. Illustrations, index. -
Ranada, David. “Digital Debut: First Impressions of the Compact Disc System.” Stereo Review 48 (December, 1983): 61-70. Review article looks at the first compact disc players sold in the United States. Explains the theories involved and outlines the historical development. Very readable. Photographs. -
Rohlfs, Jeffrey H. Bandwagon Effects in High Technology Industries. Cambridge, Mass.: MIT Press, 2001. Demonstrates how the bandwagon effect has manifested in high-technology industries. Case studies include telephones, CD players, VCRs, and the Internet, among others. -
Schetina, Erik S. The Compact Disc. Englewood Cliffs, N.J.: Prentice Hall, 1989. Short, but generally quite readable. Aimed at the hobbyist. Illustrations, index.
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