Editing Dolby noise-reduction system (section)

{{Short description|A line of noise reduction systems for reel-to-reel, compact cassette, and videocassette recorders}}
{{use dmy dates|date=July 2021|cs1-dates=y}}
{{Use American English|date=October 2022}}
{{infobox brand
|name           = Dolby noise-reduction system
|logo           = 
|logo_size      = 
|image          = Dolby361.jpg
|caption = Dolby 361 A-type noise reduction module
|type           = Audio technology 
|currentowner   = [[Dolby Laboratories]]
|origin         = United Kingdom<br />United States
|introduced     = 1965
|discontinued   =
|markets        = Worldwide
|website        = [https://www.dolby.com/ Dolby official website]
|related        = [[Dolby Stereo]] (1976-present)<br />[[Dolby Digital]] (1986-present)
|previousowners = [[Ray Dolby]]
}}
A '''Dolby noise-reduction system''', or '''Dolby&nbsp;NR''', is one of a series of [[Audio noise reduction|noise reduction]] systems developed by [[Dolby Laboratories]] for use in analog audio tape recording.<ref name="White1996"/> The first was ''[[#Dolby A|Dolby&nbsp;A]]'', a professional [[broadband]] noise reduction system for recording studios that was first demonstrated in 1965, but the best-known is ''[[#Dolby B|Dolby&nbsp;B]]'' (introduced in 1968), a sliding band system for the consumer market, which helped make high fidelity practical on [[cassette tape]]s, 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&nbsp;A'' and ''[[#Dolby SR|Dolby&nbsp;SR]]'' were developed for professional use. ''Dolby&nbsp;B'', ''[[#Dolby C|C]]'', and ''[[#Dolby S|S]]'' were designed for the consumer market. Aside from [[#Dolby HX/HX-Pro|Dolby&nbsp;HX]], all the Dolby variants work by [[companding]]:  compressing the [[dynamic range]] of the sound during recording, and expanding it during playback.