Today we celebrate the birthday of Ray Dolby (18 Jan 1933), the American engineer and physicist who invented the Dolby Noise Reduction System.
Dolby started his career in sound engineering while still at school, when he worked part-time at the Ampex Corporation. During his college years he became part of a team of engineers who invented the first practical video tape recorder in 1956. He subsequently started his own company, Dolby Laboratories, where he developed his noise reduction technologies, starting with Dolby A (1966), a broadband audio compression and expansion technique aimed at recording studios, with which audible tape hiss in professional tape recording can be significantly reduced without any discernible side-effects.
While Dolby A had real impact in the recording industry, perhaps the better known technology is Dolby B (1968), a sliding band noise reduction system aimed at the consumer market, which helped achieve high fidelity on cassette tapes.
All the Dolby variants work through a technique dubbed ‘companding’, which involves compressing the dynamic range of the sound during recording (‘dynamic pre-emphasis’), and expanding it during playback (‘dynamic de-emphasis’). This basically comes down to increasing the volume of low-level high-frequency sounds during recording and correspondingly reducing them during playback, thus reducing audible levels of tape hiss.
Various further iterations of Dolby’s audio noise reduction have subsequently been introduced, including Dolby C (1980), Dolby SR (1986) and Dolby S (1989).
Beyond noise reduction, Dolby Laboratories have also done ground-breaking work in the field of digital audio encoding and compression. Dolby Digital – first developed for movie theatres and later implemented in DVDs – is a digital audio compression format that was instrumental in the popularisation of surround sound. It has also been adopted as output format in most video game consoles, and several personal computers. Subsequent iterations of this technology include Dolby Digital EX, Dolby Digital Plus and Dolby Digital Live.
To say that Ray Dolby and his noise reduction and audio compression technologies have influenced the way we experience recorded sound, is an understatement. He has fundamentally shaped the way sound is recorded and reproduced, and his technologies have become so pervasive in sound reproduction that it is almost impossible to quantify its impact.