title: how to compare two audio signals with Matlab
body: <p>I have two audio signas that I want to compare using Matlab, my problem is that I can hear the difference between them loud and clear, but when use the function <code>pwelch</code> to compare their PSD ,I don't see much difference between them,any idea how can I compare them with a different methode ! thanks in advance ! 
  PS:   1.  I already ask the quesiton in DSP.stackexchange but had no answer!
        2. I'm not asking for codes, that'S why I didn't put mine ! </p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>after the answer of @Bas Swinckels here the code par that I'm using the result and I still can't see a way that the describ this  ?</p>
  
  <pre><code>  clear;
  clc;
  [x0,Fs] = audioread('Nonoise.wav');
  x0 = x0(:,1);
  [Y0,G] = pwelch(x0,hamming(512));
  plot(G,10*log10(Y0));
  grid on 
  
  [x50,Fs] = audioread('50% noise.wav');
  x50 = x50(:,1);
  [Y50,G] = pwelch(x50,hamming(512));
  hold on ;
  plot(G,10*log10(Y50),'r');
  
  
  [x100,Fs] = audioread('100% noisy.wav');
  x100 = x100(:,1);
  [Y100,G] = pwelch(x100,hamming(512));
  hold on ;
  plot(G,10*log10(Y100),'g');
  
  %% spectrogram  
  spectrogram(x0,hann(64),32,64,Fs)
  figure();
  spectrogram(x50,hann(64),32,64,Fs)
  figure();
  spectrogram(x100,hann(64),32,64,Fs)
  </code></pre>
  
  <p>and here are the result :</p>
  
  <p><img src="https://i.stack.imgur.com/jbAG4.jpg" alt="pwelch result "></p>
  
  <p><img src="https://i.stack.imgur.com/VbOG5.jpg" alt="no noise or no effect "></p>
  
  <p><img src="https://i.stack.imgur.com/wiXo3.jpg" alt="50 percent "></p>
  
  <p><img src="https://i.stack.imgur.com/vorIS.jpg" alt="100 percent noisy "></p>
  
  <p>can anybody tell me how does the noise or the effect that I'm adding to the source influences my spectrum ? </p>