Patent ID: 6556682
Filing Date: 2003-04-29
Classification: H04M

Abstract:
An echo cancellation method on N sound signal channels each having a loudspeaker and an associated microphone, N being an integer greater than or equal to 1, according to which, on each of the N channels:(a) a synthetic signal is created having the spectral characteristics of a white noise, the spectrum of this signal extending over several adjacent frequency bands, and this synthetic signal being uncorrelated with the synthetic signals created on the other channels; (b) for each frequency band, a frequency masking threshold is computed corresponding to the signal associated with the loudspeaker of the considered channel by using properties of human auditory perception; (c) in each frequency band, the synthetic signal level is brought to the value of the associated frequency masking threshold, so as to obtain an auxiliary signal; (d) the auxiliary signal is added to the signal associated with the loudspeaker of the considered channel, the frequency masking thresholds having been previously computed so as to make the auxiliary signal inaudible, and the auxiliary signals of the N channels being mutually uncorrelated; (e) the signal obtained in step (d) is supplied as input to an adaptive filter the coefficients of which form an estimation of the impulse response of the acoustic coupling path between the loudspeaker and the microphone associated with the sound signal channel considered; (f) the signals obtained as output from the N adaptive filters associated with each microphone channel are added and the resultant of the signal is subtracted from the signal received by the microphone associated with this channel; (g) an estimation error is computed from the difference obtained at the outcome of the previous subtraction; (h) the coefficients of the adaptive filters associated with the considered microphone channel are corrected as a function of the associated estimation error.