reading, writing and processing .wav files in Matlab
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Haraldur Mímir Bjarnason
on 24 Aug 2015
Commented: Star Strider
on 30 Aug 2015
Im on a school project and my problem is that I have a .wav file and I want to find the highest Db vs. frequency (Hertz) in that file. I'm measuring what frequency will sound (in the human ear) the highest. So I need a plot Db vs. frequency.
any idea?
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Star Strider
on 25 Aug 2015
The fft function will do what you want, although you have to specify the magnitude of the fft in dB. The documentation for fft has the essential code between the first two figures in the documentation. You will need the log10 function to calculate dB from the magnitude.
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Star Strider
on 30 Aug 2015
Here is the approach I outlined, with a synthesised signal since I don’t have your .wav file:
t = linspace(0, 1, 1E+4); % Create Signal
y = sin(2*pi*t*100) + cos(2*pi*t*50);
Fs = 1/mean(diff(t));
Fn = Fs/2; % Nyquist Frequency
fty = fft(y)/length(y); % Take FFT & Normalise
fv = linspace(0, 1, fix(length(fty)/2)+1)*Fn; % Frequency Vector For Plot
iv = 1:length(fv); % Index Vector For Plot
figure(1)
plot(fv, 20*log10(abs(fty(iv)))) % Plot In dB
xlabel('Frequency (Hz)')
ylabel('Amplitude (dB)')
axis([0 250 ylim])
You will likely have to experiment to get the result you want with your signal.
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