title: Merge all .wav files in a folder that start by the same prefix
body: <p>I have filelists that look like this:</p>
  
  <pre><code>S134_001.wav
  S134_002.wav
  S134_003.wav
  S149_001.wav
  S149_002.wav
  S149_003.wav
  S16_001.wav
  S16_002.wav
  S16_003.wav
  S16_004.wav
  S16_005.wav
  S16_006.wav
  S272_001.wav
  S272_002.wav
  S272_003.wav
  S272_004.wav
  S272_005.wav
  S272_006.wav
  S272_007.wav
  S374_001.wav
  S396_001.wav
  S92_001.wav
  </code></pre>
  
  <p>And I want to merge S134_001.wav, S134_002.wav, S134_003.wav into S134.wav; S149_001.wav, S149_002.wav and S149_003.wav into S149.wav; and so on ( preferably using sox ).</p>
  
  <p>I also want to delete the original files.</p>
  
  <p>How do I achieve that? Bash is the preferred solution, but any programming language will do. Thanks.</p>