US 7,254,241 B2 · System and process for robust sound source localization

Abstract

A system and process for finding the location of a sound source using direct approaches having weighting factors that mitigate the effect of both correlated and reverberation noise is presented. When more than two microphones are used, the traditional time-delay-of-arrival (TDOA) based sound source localization (SSL) approach involves two steps. The first step computes TDOA for each microphone pair, and the second step combines these estimates. This two-step process discards relevant information in the first step, thus degrading the SSL accuracy and robustness. In the present invention, direct, one-step, approaches are employed. Namely, a one-step TDOA SSL approach and a steered beam (SB) SSL approach are employed. Each of these approaches provides an accuracy and robustness not available with the traditional two-step approaches.

Claims13

Dependent claims

A computer-implemented sound source localization process for finding the location of a sound source using signals output by a microphone array having a plurality of audio sensors, comprising the following process actions:

inputting the signal generated by each audio sensor of the microphone array;
and
selecting as the location of the sound source, a location that maximizes a sum of weighted cross correlations between the input signal from a first sensor and the input signal from the second sensor for pairs of array sensors, wherein the weighted cross correlations are weighted using a weighting function that enhances the robustness of the selected location of the sound source by mitigating an effect of uncorrelated noise and/or reverberation.

A computer-readable medium having computer-executable instructions for finding the location of a sound source using signals output by a microphone array having a plurality of audio sensors, said computer-executable instructions comprising:

(a) computing a N-point FFT of the input signal from each sensor;
(b) establishing a set of candidate sound source locations;
(c) selecting a previously unselected one of the candidate sound source locations;
(d) selecting a previously unselected pair of sensors in the microphone array;
(e) estimating the energy across a prescribed range of frequencies (f) associated with the sound coming from the selected candidate sound source location to the selected pair of sensors via the equation, |Wrs(f)Xr(f)Xs*(f)exp(−j2πf(τr−τs))|2, where r and s refer to a first and second sensor, respectively, of the selected pair of array sensors, Xr(f) is the N-point FFT of the input signal from the first sensor in the selected sensor pair, Xs(f) is the N-point FFT of the input signal from the second sensor in the selected sensor pair, τr is the time it takes sound to travel from the selected sound source location to the first sensor of the selected sensor pair, τs is the time it takes sound to travel from the selected sound source location to the second sensor of the selected sensor pair, and Wrs is a weighting function for mitigating the effect of both correlated and reverberation noise defined by the equation,
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where |Nr(f)|2 is the noise power spectrum associated with the signal from the first sensor of the selected sensor pair, |Ns(f)|2 is noise power spectrum associated with the signal from the second sensor of the selected sensor pair, and q is a prescribed proportion factor set to an estimated ratio between the energy of the reverberation and total signal at the selected sensors;
(f) repeating actions (d) and (e) until all sensor pairs of interest have been selected;
(g) summing the energy of the sound coming from the selected candidate sound source location estimated for each of the microphone array sensor pairs;
(h) repeating actions (c) through (g) until all the candidate sound source locations have been selected;
and
(i) designating the candidate sound source location associated with the highest total estimated energy as the location of the sound source.

107 more elements

Dependencies are inferred from the claim text.

System and process for robust sound source localization

Life of this patent

System and process for robust sound source localization

Life of this patent

Abstract

Claims13