Patent ID: 7574008

Claim:
A method comprising: for each time frame of a set of time frames, generating an alternative sensor value representing an alternative sensor signal using an alternative sensor other than an air conduction microphone; for each time frame of the set of time frames, generating an air conduction microphone value; identifying which frames in the set of frames do not contain speech from a speaker based on the energy level of the alternative sensor signal; within the frames identified as not containing speech from the speaker, performing speech detection on the air conduction microphone values to determine which frames contain background speech and which frames do not contain background speech; using alternative sensor values for the frames identified as not containing speech from the speaker and not containing background speech to determine a variance for noise of the alternative sensor; using alternative sensor values and air conduction microphone values for the frames identified as not containing speech from the speaker but containing background speech to determine a channel response of the alternative sensor to background speech; using the alternative sensor values and the air conduction microphone values for the set of time frames to estimate a value for a channel response of the alternative sensor to speech from the speaker; and using the channel response of the alternative sensor to speech from the speaker, the channel response of the alternative sensor to background speech, and the variance for noise of the alternative sensor to estimate a noise-reduced value for each time frame in the set of time frames.