Patent ID: 7209567

Claim:
A method of reducing noise in a communication system, the method comprising: averaging an input sound signal's magnitude spectrum over multiple time frames to reduce musical noise; determining an average magnitude of a noise spectrum while speech is not present on the input sound signal, wherein the average magnitude is determined for each of a plurality of discrete frequencies of the noise spectrum; determining a maximum ratio of noise to average noise over each of a plurality of sub-bands; determining a running average of the maximum ratio of noise to average noise over each sub-band; receiving an indication that speech may be present on the input sound signal; and for each of a plurality of frames while receiving the indication that speech may be present on the input sound signal; detecting whether speech is present; while speech is detected, estimating a speech signal magnitude for each discrete frequency by subtracting from the input sound signal magnitude for that discrete frequency the average noise for that discrete frequency multiplied by the lesser of (a) a ratio of a sum of noise-corrupted speech to a sum of average noise for the frequency sub-band containing that discrete frequency and (b) the running average of the maximum ratio of noise to average noise for the frequency sub-band containing that discrete frequency; and while speech is not detected, estimating the speech signal magnitude to be zero.