Acoustic Beamforming Using a Rectangular Microphone Array

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Using the Mathworks example:
I am reproducing this code using a rectangular 4x4 array rather than the linear array. I am in the header: Simulate the Received Signals
i am only using one audio signal x1 how do i use the step function?
i tried
temp=step(hCollector, x1,ang_dft+sqrt(noisePwr)*rand(rs,NSamPerFrame,[4
4]));
The error I received is:
Warning: Input arguments must be scalar.
Error using +
Matrix dimensions must agree.
Error in file (line 47)
temp=step(hCollector, x1,ang_dft+sqrt(noisePwr)*rand(rs,NSamPerFrame,[4
4]));
how do i correctly execute this?
here is my code:
H = phased.OmnidirectionalMicrophoneElement('BackBaffled',true)
fc=[200 300 400]
ang = [0;0];
resp=step(H,fc,ang);
plotResponse(H,200,'RespCut','Az','Format','Polar')
ha = phased.URA([4 4],[0.00635 0.00635],'Element',H)
figure;
plotResponse(ha,200,340,'RespCut','3D','Format','Polar')
%---------------------
ang_dft = [-10,10]
fs= 8000
hCollector = phased.WidebandCollector('Sensor',ha,'PropagationSpeed',340,'SampleRate',fs,'ModulatedInput',false);
t_duration = 3;
t=0:1/fs:t_duration/fs;
rs= RandStream.create('mt19937ar','Seed',2008)
noisePwr = 1e-4
%preallocate
NSamPerFrame =1000
NTSample = t_duration*fs
sigArray = zeros(NTSample,[4 4])
voice_dft= zeros(NTSample,1)
%set audio player
isAudioSupported = audiodevinfo(0)
if isAudioSupported
hap = dsp.AudioPlayer('SampleRate',fs)
end
%simulate
for m=1:NSamPerFrame:NTSample
sig_idx=m:m+NSamPerFrame-1
x1=wavread('dft_voice_8kHz',[sig_idx(1) sig_idx(end)])
temp=step(hCollector, x1,ang_dft+sqrt(noisePwr)*rand(rs,NSamPerFrame,[4 4]));
if isAudioSupported
step(hap,temp(:,3));
end
sigArray(sig_idx,:)=temp;
voice_dft(sig_idx)=x1;
end
plot(t,sigArrary(:,3));
  1 Comment
Nick Yiw
Nick Yiw on 18 Mar 2019
Hi, I am a student currently working on a project that involves distance speech recognition for controlling output. I really want to know what are the best recommendations of microphone arrays/chips that I can use which are compatible with MATLAB. Thank you.

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Accepted Answer

Honglei Chen
Honglei Chen on 7 Mar 2013
The error is because you are adding noise to the angle. I believe it's a typo. That line should just reads like this
temp=step(hCollector, x1,ang_dft)+sqrt(noisePwr)*rand(rs,NSamPerFrame,16);
Also, in the earlier part of the script, where you instantiate sigArray, it should be
sigArray = zeros(NTSample,16);
HTH
  3 Comments
Honglei Chen
Honglei Chen on 11 Mar 2013
Hi OSheen,
The first step of a Frost beamformer is time delay steering so there is no need to add a time delay beamformer in front of Frost beamformer.
As to the error you saw, it is because in your configuration, the steering angle for the time delay beamformer is specified in the property of 'Direction'. Therefore, the syntax for performing time delay beamforming is
y = step(hbf,x)
If you really want to add a Frost beamformer afterwards, what you need to do is passing the y into the Fromst beamformer, e.g.
y2 = step(hbf2,y,ang_dft)
HTH
Osheen
Osheen on 12 Mar 2013
Thank you for your helpful response.
How would I apply the Frost beamformer on REAL data collected from a 4x4 microphone array? Also what is the best way to determine the FIR filter length of the beamformer?
Here is some code I have written so far to apply on real collected data. Please let me know if I am missing something
data = getdata(ai)
hmic=phased.OmnidirectionalMicrophoneElement;
ha=phased.URA([4 4],[0.0635 0.0635],'Element',hmic);
hsig=dsp.SignalReader('Signal',data,'SamplesPerFrame',NSampPerFrame);
frost=phased.FrostBeamformer('SensorArray',ha,'SampleRate',Fs,...
'PropagationSpeed',c,'FilterLength',100,'DirectionSource','Input port');
frostout=zeros(NTSample,1);
for m=1:NSampPerFrame:nt
frostout(m:m+NSampPerFrame-1,:)=step(frost,step(hsig),angSteer);
end
soundsc(frostout,Fs,16)
wavwrite(frostout,'Frostbeamformed real data');
plot(t,frostout);
xlabel('Time (sec)'); ylabel ('Amplitude (V)');
title('Frost Beamformer Output');

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More Answers (1)

Zeynep Ertekin
Zeynep Ertekin on 22 Jan 2017
Hi,
I need a 2d or 3d sound source localization code with command load; can anyone please help me. Any help will be highly apprecited.

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