Editing Dolby noise-reduction system (section)

===Dolby FM===
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In the early 1970s, some expected Dolby&nbsp;NR to become normal in [[FM radio]] broadcasts and some tuners and amplifiers were manufactured with decoding circuitry; there were also some tape recorders with a Dolby&nbsp;B "pass-through" mode. In 1971 [[WFMT]] started to transmit programs with Dolby&nbsp;NR,<ref name="Gilmore1971"/> and soon some 17 stations broadcast with noise reduction, but by 1974 it was already on the decline.<ref name="Free1974"/> Dolby&nbsp;FM was based on Dolby&nbsp;B,<ref name="Mielke1977"/> but used a modified 25&nbsp;μs pre-emphasis time constant<ref name="Reuber_1983"/> and a frequency-selective [[companding]] arrangement to reduce noise.

A similar system named [[High Com FM]] was evaluated in Germany between July 1979 and December 1981 by [[Institut für Rundfunktechnik|IRT]],<ref name="Schroeder"/> and field-trialed up to 1984. It was based on the [[Telefunken]] [[High Com]] broadband compander system, but never introduced commercially in FM broadcasting.<ref name="IRT1981"/> Another competing system was [[FMX (broadcasting)|FMX]], which was based on [[CX (audio)|CX]].

[[File:Sony TC-RX55 cassette deck.jpg|thumb|right|400px|A typical consumer cassette deck from the late 1980s, featuring automatic reverse, electronic transport controls, and Dolby&nbsp;B and C, among other features]]