Abstract: A multi-microphone hands-free device operating in noisy surroundings implements a method of de-noising a noisy sound signal. The noisy sound signal comprises a useful speech component coming from a directional speech source and an unwanted noise component, the noise component itself including a lateral noise component that is non-steady and directional. The method operates in the frequency domain and comprises combining signals into a noisy combined signal, estimating a pseudo-steady noise component, calculating a probability of transients being present in the noisy combined signal, estimating a main arrival direction of transients, calculating a probability of speech being present on the basis of a three-dimensional spatial criterion suitable for discriminating amongst the transients between useful speech and lateral noise, and selectively reducing noise by applying a variable gain specific to each frequency band and to each time frame.

Abstract: A multi-microphone hands-free device distinguishes between non-steady noise and speech and adapts the de-noising to the presence and characteristics of the detected non-steady noise without spoiling any speech that is present. In the frequency domain, the method comprises calculating a first noise reference by analyzing spatial coherence of signals picked up, calculating a second noise reference by analyzing directions of incidence of signals picked up, estimating a main direction of incidence of signals picked up, selecting as a referent noise signal noise references as a function of estimated main direction, combining signals picked up into a noisy combined signal, calculating probability that speech is absent in the noisy combined signal on basis of respective spectral energy levels of the noisy combined signal and of the referent noise signal, and selectively reducing noise by applying variable gain that is specific to each frequency band and to each time frame.

Abstract: 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.

Abstract: The method comprises the following steps in the frequency domain: a) combining signals into a noisy combined signal; b) estimating a pseudo-steady noise component; c) calculating a probability of transients being present in the noisy combined signal; d) estimating a main arrival direction of transients; e) calculating a probability of speech being present on the basis of a three-dimensional spatial criterion suitable for discriminating amongst the transients between useful speech and lateral noise; and f) selectively reducing noise by applying a variable gain specific to each frequency band and to each time frame.