04630305 is referenced by 216 patents and cites 18 patents.

An automatic gain selector is disclosed for use with a noise suppression system which performs speech quality enhancement upon a noisy speech signal available at the input to generate a noise-suppressed speech signal at the output by spectral gain modification. The channel gain controller (240) of the present invention produces a modification signal (245), comprised of individual channel gain values, for application to a channel gain modifier (250). A particular gain table set is automatically selected from one of a plurality of gain tables (450) by a selector switch (470) and a noise level quantizer (440) in response to a multi-channel noise parameter, such as the overall average background noise level of the input signal. Then the individual channel gain values (455) are obtained from the particular gain table set in response to the individual channel signal-to-noise ratio estimate (235). Hence, each individual channel gain value is selected as a function of (a) the channel number, (b) the current channel SNR estimate, and (c) the overall average background noise level. The automatic gain selector further includes a gain smoothing filter (460) for smoothing these noise suppression gain factors on a per-sample basis thereby improving noise flutter performance caused by step discontinuities in frame-to-frame gain changes.

Title
Automatic gain selector for a noise suppression system
Application Number
6/750941
Publication Number
4630305
Application Date
July 1, 1985
Publication Date
December 16, 1986
Inventor
Richard J Vilmur
Palatine
IL, US
Philip J Smanski
Palatine
IL, US
Ira A Gerson
Hoffman Estates
IL, US
David E Borth
Palatine
IL, US
Agent
Charles L Warren
Donald B Southard
Douglas A Boehm
Assignee
Motorola
IL, US
IPC
H04B 15/00
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