code: def convert_to_wav(self, filename):
          
          temp_filename = '{0}.wav'.format(self.temp_filename())
          self.run(['sox', '-G', '-c', '1', filename, temp_filename])
          return temp_filename
docs: Uses sox cmdline tool, to convert audio file to .wav
  
          Note: for testing, use -
          http://www.text2speech.org/,
          with American Male 2 for best results