The invention of the phonograph and the record were the key sound recording advancements until the advent of magnetic audiotape and tape players in the 1940s. Magnetic tape sound recording was first developed as early as 1929 and further refined in the 1930s, but it didn’t catch on initially because the first machines were bulky reel-to-reel devices, the amount of tape required to make a recording was unwieldy, and the tape itself broke or damaged easily. However, owing largely to improvements by German engineers who developed plastic magnetic tape during World War II, audiotape eventually found its place.

Audiotape’s lightweight magnetized strands finally made possible sound editing and multiple-track mixing, in which instrumentals or vocals could be recorded at one location and later mixed onto a master recording in another studio. This led to a vast improvement of studio recordings and subsequent increases in sales, although the recordings continued to be sold primarily in vinyl format rather than on reel-to-reel tape. By the mid-1960s, engineers had placed miniaturized reel-to-reel audiotape inside small plastic cassettes and had developed portable cassette players, permitting listeners to bring recorded music anywhere and creating a market for prerecorded cassettes. Audiotape also permitted “home dubbing”: Consumers could copy their favorite records onto tape or record songs from the radio. This practice denied sales to the recording industry, resulting in a drop in record sales, the doubling of blank audiotape sales during a period in the 1970s, and the later rise of the Sony Walkman, a portable cassette player that foreshadowed the release of the iPod two decades later.

Some thought the portability, superior sound, and recording capabilities of audiotape would mean the demise of records. Although records had retained essentially the same format since the advent of vinyl, the popularity of records continued, in part due to the improved sound fidelity that came with stereophonic sound. Invented in 1931 by engineer Alan Blumlein, but not put to commercial use until 1958, stereo permitted the recording of two separate channels, or tracks, of sound. Recording-studio engineers, using audiotape, could now record many instrumental or vocal tracks, which they “mixed down” to two stereo tracks. When played back through two loudspeakers, stereo creates a more natural sound distribution. By 1971, stereo sound had been advanced into quadrophonic, or four-track, sound, but that never caught on commercially.

The biggest recording advancement came in the 1970s, when electrical engineer Thomas Stockham made the first digital audio recordings on standard computer equipment. Although the digital recorder was invented in 1967, Stockham was the first to put it to practical use. In contrast to analog recording, which captures the fluctuations of sound waves and stores those signals in a record’s grooves or a tape’s continuous stream of magnetized particles, digital recording translates sound waves into binary on-off pulses and stores that information as numerical code. When a digital recording is played back, a microprocessor translates these numerical codes back into sounds and sends them to loudspeakers. By the late 1970s, Sony and Philips were jointly working on a way to design a digitally recorded disc and player to take advantage of this new technology, which could be produced at a lower cost than either vinyl records or audiocassettes. As a result of their efforts, digitally recorded compact discs (CDs) hit the market in 1983.

By 1987, CD sales were double the amount of LP record album sales (see Figure 4.1). By 2000, CDs rendered records and audiocassettes nearly obsolete, except for DJs and record enthusiasts who continued to play and collect vinyl LPs. In an effort to create new product lines and maintain consumer sales, the music industry promoted two advanced digital disc formats in the late 1990s, which it hoped would eventually replace standard CDs. However, the introduction of these formats was ill-timed for the industry, because the biggest development in music formatting was already on the horizon—the MP3.