MATLAB: Sound source localization using Phased Array System Toolbox

directionlocalizationmicrophone arrayPhased Array System Toolboxsoundsound localizationwideband

I want to use a microphone array to localize sound sources, i.e. find the directions (and possibly distances) of sound sources from the array. I have examined the Direction of Arrival (DoA) finding tools in the Phased Array System Toolbox, but I am not sure if I could use these for my application. All these tools assume that the signal arriving at the array is narrowband, i.e. a single carrier frequency with some modulation. However, the sounds I am interested in are wideband, like most sounds.

Could I sub-divide my wideband sounds into a set of narrowband components (e.g. using a filter bank), and then apply the narrowband DoA tools to each sub-band separately? How could I then combine the multiple sub-band DoA's to best estimate the overall DoA? Is this approach valid, or are the narrowband DoA tools simply not applicable to sound signals?

Any help is much appreciated.

Best Answer

Most DOA estimator shipped in Phased Array System Toolbox is indeed narrow band so they are probably not the best tool for wideband audio signals.

However, you could consider using a wideband beamformer to scan the space and look for the direction where you get the maximum peak. There are several wideband beamformers available in Phased Array System Toolbox. The phased.SubbbandPhaseShiftBeamformer uses the subband approach you described in your post. You can also use phased.TimeDelayBeamformer to perform time domain beamforming which does not assume whether the signal is narrowband or wideband.

Does this address your concern? Please let me know if you need any further clarification.

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bf = phased.TimeDelayBeamformer('DirectionSource','Input port');
az = -90:90;
y = zeros(1,numel(az));
for m  = 1:numel(az)
  y(m) = rms(step(bf,x,[az(m);0]));
end
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est_az = az(idx);  % estimated angle

Note that you should be able to pick any wideband beamformer to do this.

HTH

Best Answer

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