Ray Milton Dolby Hon OBE, HonFREng was an American engineer and inventor of the noise reduction system known as Dolby NR. He helped develop the video tape recorder while at Ampex and was the founder of Dolby Laboratories.
Dolby (left) being inducted into the National Inventors Hall of Fame, 2004
Dolby noise-reduction system
A Dolby noise-reduction system, or Dolby NR, is one of a series of noise reduction systems developed by Dolby Laboratories for use in analog audio tape recording. The first was Dolby A, a professional broadband noise reduction system for recording studios in 1965, but the best-known is Dolby B, a sliding band system for the consumer market, which helped make high fidelity practical on cassette tapes, which used a relatively noisy tape size and speed. It is common on high-fidelity stereo tape players and recorders to the present day, although Dolby has as of 2016 ceased licensing the technology for new cassette decks. Of the noise reduction systems, Dolby A and Dolby SR were developed for professional use. Dolby B, C, and S were designed for the consumer market. Aside from Dolby HX, all the Dolby variants work by companding: compressing the dynamic range of the sound during recording, and expanding it during playback.
A Dolby 361 A-type noise reduction module
Three different music cassettes encoded with Dolby B, showing the various ways in which the use of the system could be indicated. You Don't Bring Me Flowers uses a simple Dolby logo; Apurimac uses a Dolby logo with "B NR" (also with "HX PRO" to indicate the complementary use of that technology); Tour De Force uses a Dolby logo with "Dolby System."
Advent Corporation tape recorder with Dolby noise-reduction system (ca. 1972)
A typical consumer cassette deck from the late 1980s, featuring automatic reverse, electronic transport controls, and Dolby B and C, among other features