I tried to run the code, but got an error (Mac OSX 10.8.3, portaudio-19.20111121).
This is a known problem? There is the solution?

• listening. CTRL+C to finish.
  Traceback (most recent call last):
  File "stt_google.py", line 102, in
  listen_for_speech()
  File "stt_google.py", line 44, in listen_for_speech
  data = stream.read(512)
  File "/Users/......./lib/python2.7/site-packages/pyaudio.py", line 605, in read
  return pa.read_stream(self._stream, num_frames)
  IOError: [Errno Input overflowed] -9981