Patent ID: 7440891
Filing Date: 2008-10-21
Classification: G10L,H04M,H04R

Abstract:
1. A speech processing apparatus which recognizes speech of a person in a car, comprising: generation means for generating a pseudo acoustic echo signal for each sample, said samples being based on a current impulse response simulating an acoustic echo transfer path and on a source signal; supply means for holding the current impulse response for each sample and supplying the current impulse response to said generation means; elimination means for subtracting said pseudo acoustic echo signal from a near-end speech signal to remove an acoustic echo component and thereby generate an acoustic signal which has been echo-canceled for each sample; update means for continually updating the impulse response for each sample by using said source signal, said acoustic echo-canceled signal and the current impulse response held by said supply means and for supplying the updated impulse response to said supply means; decision means for checking in each frame, said frames being comprised of plurality of samples, whether or not a voice is included in the near-end speech signal, by using time domain information and frequency domain information of said acoustic signal after said acoustic signal has been echo-canceled, said decision means outputting a result indicating whether said voice is included in the near-end speech signal; storage means for storing one or more impulse responses in each frame; control means for, in a frame for which the result of decision made by said decision means is negative, storing in said storage means the current impulse response held by said supply means and, in a frame for which the result of the decision is positive, retrieving one of the impulse responses stored in said storage means and supplying the one of the impulse responses to said supply means; means for determining a spectrum for each frame by performing the Fourier transform on said acoustic echo-canceled signal; means for successively determining a spectrum mean for each frame based on the spectrum obtained; and means for successively subtracting the spectrum mean from the spectrum calculated for each frame from said acoustic echo-canceled signal to remove additive noise of an unknown source, wherein said source signal is an output signal of a speaker of said speech processing apparatus in the car, said acoustic echo transfer path is a path from the output signal of the speaker of said speech processing apparatus in the car to an input signal of a microphone of said speech processing apparatus in the car, said near-end speech signal is a signal of the speech of the person in the car and said additive noise of an unknown source is the car's noise with energy level of between 60 dBA and 80 dBA.