Origins

     Ray Dolby founded Dolby Laboratories in London in 1965. Dolby's career began in high school when he worked for Ampex Corporation in Redwood City, California. While still in college he worked with a team of Ampex engineers to invent the first practical video tape recorder, which was introduced to the broadcast industry in 1956 (Dolby was largely responsible for the machine's electronics). Dolby graduated from Stanford University in 1957 and received his Ph.D. in physics from Cambridge University in 1961. Dolby Laboratories moved its headquarters to San Francisco in 1976.

     The first commercial product from the company was Dolby A, a noise reduction system using audio compression and expansion to reduce background hiss without the discernible ​​side effects of conventional wide-band companders. More than any other feature, the system's freedom from side effects is what differentiated Dolby NR from previous attempts at audio noise reduction and ultimately helped earn its reputation. Also incorporated in this new noise reduction system was the ability to treat only soft signals, leaving unprocessed the loud signals that naturally mask noise.

     A consumer version of the noise reduction system, called Dolby B, was released in 1968. Instead of dividing the signal into fixed multiple bands (as did Dolby A), Dolby B NR used a single, less-costly sliding band of compression that reduced noise in the higher frequency hiss region where most of the noise of consumer tape recording occurs. But the system needs the reference levels to be precisely set. Dolby NR is perhaps·best known for its use with magnetic tape. The first product to use Dolby B was an open reel tape recorder made by KLH in 1968, but it made its biggest impact in the compact cassette format; with its inherent tape hiss problem and slow speed, cassette tape was a natural for Dolby B noise reduction.

Applications to Radio

     The first experimental FM broadcasts using Dolby NR were made by WFMT in Chicago in June 1971 using the model 320 B noise reduction system. In March 1972 WQXR in New York City began full-time FM broadcasting using Dolby B.

     In June 1973 it was proposed that Dolby B be joined with 25 microseconds pre-emphasis for FM broadcasting. In February 1974 this became the Dolby FM system demonstrated to the Federal Communications Commission (FCC). In June the FCC approved Dolby FM broadcasts. By August 1975 about 100 U.S. stations were broadcasting in Dolby FM. The use of Dolby FM moved outside the United States in October when the Canadian Department of Communications approved its use for broadcast.

Reducing Noise in Digital Signals

     Concurrent with the development of these analog systems, Dolby Labs began research into digital audio in 1982. The primary goal was to find ways to reduce the amount of data required to transmit and store high-quality digital audio. Dolby Labs moved into the world of digital encoding schemes with AC-1, a refined form of Adaptive Delta Modulation (ADM). AC-1 was introduced in 1984, when bit rate reduction was in its infancy, and adopted the next year for use in a number of direct satellite broadcast and cable distribution systems. The Australian Broadcasting Corporation adopted it for direct broadcast satellite in its AUSSAT I in October 1985.

     Dolby began its work in digital radio with the Digital Studio to Transmitter Line (DSTL) system, which was demonstrated for the first time in September 1991 in San Francisco at the National Association of Broadcasting's "Radio '91" conference. DSTL is a design featuring low time-delay implementation of Dolby AC-2, its second-generation digital encoding scheme using ADM. It features two high-quality channels and two auxiliary channels in the same spectrum space used for narrowband FM composite signals. Dolby DSTL was first installed in May 1992 at WWKX FM in Providence, Rhode Island.

     Dolby Fax, for linking worldwide facilities with digital audio, began U.S. sales in March 1994. Dolby Fax uses Dolby AC-2 digital audio coding over two ISDN lines for high-quality transmission worldwide. In May 1994 DMX for Business began as the first direct broadcast satellite service, with Dolby AC-3 digital audio.

     Dolby Surround is a matrix process that enables any stereo (two channel) medium, analog or digital, to carry four-channel audio. Encoded program material is fully compatible with mono and stereo playback, and listeners with playback systems incorporating Dolby Surround Pro Logic decoding receive four-channel surround sound. In February 199 5 the BBC broadcast the first radio production in Dolby surround, "Bomber," on BBC Radio 4, and "Batman," "The Adventures of Superman," and "The Amazing Spiderman" on BBC Radio

     Italy's Radio 101 has used Dolby Surround for all its ​​evening entertainment programming. In March 1995 "West Coast Live" became the first U.S. radio show to be regularly broadcast in Dolby surround. In January 1997 the first Dolby Surround Pro Logic system for in-car use was launched at the Detroit Motor Show.

     Dolby moved into the world of personal computer (PC) Surround Sound in April 1996 when Dolby and Microsoft signed a letter of intent to jointly develop PC surround technologies and specifications supporting the use of Dolby Digital AC-3 and Dolby Surround Pro Logic. Dolby Digital (sometimes known as AC-3 for the technology on which it is based) is a perceptual coding for consumer applications that enables storing and transmitting between one and 5.1 audio channels at a low data rate. Dolby Digital makes it possible to store five audio channels using less data than is needed to store just one channel on a compact disc. This was followed by Dolby Net, a low-bit-rate version of Dolby Digital introduced for low-bandwidth applications such as real time streaming internet audio, in November 1996.

     In January 1997 Virtual Dolby Surround and Virtual Dolby Digital were introduced at the huge Consumer Electronics Show in Las Vegas. They enable surround sound effects from desktop computers with just two speakers. In October 1999 real time multichannel audio was streamed successfully over the internet using 5.1-channel Dolby Digital.

     In 1999 Dolby Laboratories introduced Dolby E, a profes­sional multichannel audio coding technology that allows a single AES/EBU (digital audio) pair to carry up to eight channels of audio, as well as digital metadata, through broadcast facilities. It is a convenient, simple, cost-effective conversion of two­ channel broadcast facilities to multichannel audio.

     In the world of radio, Dolby Lab's impact has been most felt with Dolby NR, as well as several other programs such as Dolby Surround, DSTL, Dolby Digital, Dolby Fax, and Dolby

     E. Although no one can predict the future of radio and the interaction with new technologies, given its track record, Dolby Labs will likely play a role in radio's future-on the airwaves, on the internet, or wherever it goes in the new millennium.