title: Change gender of voice via command line/pipe or API
body: <p>I'm looking to change the gender of a voice, man to woman and vice versa, preferably on linux. I can change the pitch, but it mostly makes the audio just sound chipmunky. </p>
  
  <p>What are the other things that make a voice gender specific? How can I change them?</p>
  
  <p>I have tried soundtouch, sox and LADSPA/Autotalent. Like I said, the main problem is the high pitch for a man->woman just sounds chipmunky. Anyone have success with this before?</p>
  
  <p>I'm looking to add this into Freeswitch, so a C API is preferable, but I can fallback to a pipe.</p>