07058572 is referenced by 39 patents and cites 14 patents.

Acoustic noise for wireless or landline telephony is reduced through optimal filtering in which each frequency band of every time frame is filtered as a function of the estimated signal-to-noise ratio and the estimated total noise energy for the frame. Non-speech bands and other special frames are further attenuated by one or more predetermined multiplier values. Noise in a transmitted signal formed of frames each formed of frequency bands is reduced. A respective total signal energy and a respective current estimate of the noise energy for at least one of the frequency bands is determined. A respective local signal-to-noise ratio for at least one of the frequency bands is determined as a function of the respective signal energy and the respective current estimate of the noise energy. A respective smoothed signal-to-noise ratio is determined from the respective local signal-to-noise ratio and another respective signal-to-noise ratio estimated for a previous frame. A respective filter gain value is calculated for the frequency band from the respective smoothed signal-to-noise ratio. Also, it is determined whether at least a respective one as a plurality of frames is a non-speech frame. When the frame is a non-speech frame, a noise energy level of at least one of the frequency bands of the frame is estimated. The band is filtered as a function of the estimated noise energy level.

Title
Reducing acoustic noise in wireless and landline based telephony
Application Number
9/493709
Publication Number
7058572 (B1)
Application Date
January 28, 2000
Publication Date
June 6, 2006
Inventor
Elias J Nemer
Montreal
CA
Agent
Mintz Levin CohnFerris Glovsky and Popeo PC
Assignee
Nortel Networks
CA
IPC
G10L 21/02
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