title: How to programmatically combine .wav files?
body: <p>I would like to play some kind of text-to-speech with only numbers. I can record 10 wav files, but how can I combine them programmatically ?</p>
  
  <p>For instance, the user types 1234, and the text-to-speech combines 1.wav with 2.wav, 3.wav and 4.wav to produce 1234.wav that plays "one two three four".</p>