Patent ID: 6950513
Filing Date: 2005-09-27
Classification: H04M

Abstract:
1. A method of setting impulse responses of first, second, third and fourth filters for echo canceling, the method comprising: generating first and second echo cancel signals by convoluting a first impulse response of the first filter provided corresponding to a first microphone and a second impulse response of the second filter provided corresponding to a second microphone, respectively, to a first sound signal supplied to a first speaker; generating third and fourth echo cancel signals by convoluting a third impulse response of the third filter provided corresponding to the first microphone and a fourth impulse response of the fourth filter provided to the second microphone, respectively, to a second sound signal supplied to a second speaker; generating a first differential signal by subtracting the first and third echo cancel signals from a first collected signal collected by the first microphone; generating a second differential signal by subtracting the second and fourth echo cancel signal from a second collected signal collected by the second microphone; performing a principal component analysis on first and second correlation signals mutually correlated to convert the first correlation signal to a first orthogonal signal and convert the second correlation signal to a second orthogonal signal which is orthogonal to the first orthogonal signal; reproducing the first orthogonal signal through the first speaker and reproducing the second orthogonal signal through the second speaker; calculating a first cross spectrum between the first differential signal and the first orthogonal signal to be reproduced by the first speaker, calculating an estimation error of the first impulse response based on the first cross spectrum, and updating characteristics of the first impulse response so as to cancel the estimation error of the first impulse response; calculating a third cross spectrum between the first differential signal and the second orthogonal signal to be reproduced by the second speaker, calculating an estimation error of the third impulse response based on the third cross spectrum, and updating characteristics of the third impulse response to cancel the estimation error of the third impulse response; calculating a second cross spectrum between the second differential signal and the first orthogonal signal to be reproduced by the first speaker, calculating an estimation error of the second impulse response based on the second cross spectrum, and updating characteristics of the second impulse response to cancel the estimation error of the second impulse response; calculating a fourth cross spectrum between the second differential signal and the second orthogonal signal to be reproduced by the second speaker, calculating an estimation error of the fourth impulse response based on the fourth cross spectrum, and updating characteristics of the fourth impulse response to cancel the estimation error of the fourth impulse response; and switching the first orthogonal signal to be reproduced by the first speaker to the first correlation signal and switching the second orthogonal signal to be reproduced by the second speaker to the second correlation signal after updating the characteristics of the first and fourth impulse responses.