OPTIMIZED METHOD OF FILTERING NON-STEADY NOISE PICKED UP BY A MULTI-MICROPHONE AUDIO DEVICE, IN PARTICULAR A HANDS-FREE TELEPHONE DEVICE FOR A MOTOR VEHICLE

摘要

In the frequency domain, the method comprises the following steps: a) calculating a first noise reference by analyzing the spatial coherence of the signals picked up; b) calculating a second noise reference by analyzing the directions of incidence of the signals picked up; c) estimating a main direction of incidence of the signals picked up; d) selecting as a referent noise signal one or the other of the noise references as a function of the estimated main direction; e) combining the signals picked up into a noisy combined signal; f) calculating a probability that speech is absent in the noisy combined signal on the basis of the respective spectral energy levels of the noisy combined signal and of the referent noise signal; and g) selectively reducing the noise by applying variable gain that is specific to each frequency band and to each time frame.