Design Con 2015

Ray Dolby dies: EE pioneer in noise reduction

-September 16, 2013

Ray Dolby, who developed the Dolby noise reduction system used in a multitude of professional and consumer audio applications, has died. An electrical engineer, Dolby invented the Dolby Sound System in 1965 at his company Dolby Laboratories, which he had founded the same year.

Ray Dolby is quoted as saying, "I've often thought that I would have made a great 19th century engineer, because I love machinery. I would have liked to have been in a position to make a better steam engine, or to invent the first internal combustion engine; to work on the first car ... I just regret that I was born in a time when most [of those types of] mechanical problems had already been solved and what remained were electronic problems." (Image courtesy of Dolby Laboratories.)

The Dolby system involved both an encoding step, used during recording, and a mirror-image decoding step, used during playback, to reduce noise in audio recordings, as described in a Dolby white paper:

The purpose of encoding is to raise the level of soft, high-frequency passages so they become louder than the tape's noise. During the trip through the Dolby encoder, loud passages (that hide tape hiss) are not altered. Soft, high-frequency passages (that tape hiss affects) are made louder than normal as they are recorded on the tape. When playing back the tape, [the] loud sounds are left unaltered, while the soft, high-frequency sounds are lowered back down to their original levels...with the noise [that was added during the recording process] automatically getting the same treatment.

Dolby Labs' first product was the encoder/decoder-based Dolby A301 Type A noise reduction unit, aimed at professional recording studios. Later versions - Dolby Type B, C and S - were designed for the consumer market. The first film that used Dolby sound was A Clockwork Orange, in 1971. Later products included Dolby Digital and Dolby Surround 7.1. See the unofficial A Chronology of Dolby Laboratories (May 1965-May 1998) for more.

For more on Ray Dolby, see Remembering Ray Dolby (4:31):

Also see Ray Dolby "Noise Reduction" (5:54):

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