Acquire Continuous Audio Data

Open Script

This example shows how to set up a continuous audio acquisition using a microphone.

Create a DataAcquisition

Create a DataAcquisition withdirectsoundas the vendor and add an audio input channel to it usingaddinput.

dq = daq("directsound"); addinput(dq,"Audio0",1,"Audio");

Set Up the FFT Plot

hf = figure; hp = plot(zeros(1000,1)); T = title('Discrete FFT Plot'); xlabel('Frequency (Hz)') ylabel('|Y(f)|') gridon;

Set ScansAvailableFcn

Update the figure with the FFT of the live input signal by setting theScansAvailableFcn.

dq.ScansAvailableFcn = @(src, evt) continuousFFT(src, hp);

Start Acquisition

The figure updates, for 10 seconds, as the microphone is used.

start(dq,"Duration",seconds(10)); figure(hf);

functioncontinuousFFT(dataHandle, plotHandle)% Calculate FFT(data) and update plot with it.data = read(daqHandle, daqHandle.ScansAvailableFcnCount,"OutputFormat","Matrix"); Fs = daqHandle.Rate; lengthOfData = length(data);% next closest power of 2 to the lengthnextPowerOfTwo = 2 ^ nextpow2(lengthOfData); plotScaleFactor = 4;% plot is symmetric about n/2plotRange = nextPowerOfTwo / 2; plotRange = floor(plotRange / plotScaleFactor); yDFT = fft(data, nextPowerOfTwo); h = yDFT(1:plotRange); abs_h = abs(h);% Frequency rangefreqRange = (0:nextPowerOfTwo-1) * (Fs / nextPowerOfTwo);% Only plot up to n/2 (as other half is the mirror image)gfreq = freqRange (1: plotRange);% Update the plotset(plotHandle,'ydata', abs_h,'xdata', gfreq); drawnowend