I used a free app to synch my I tunes with my 4g my touch andriod phone. Within I tunes I had some audio books. They transferred to my phone, but my phone does not recognize the file type which is ".aa" I tried simply renaming the files as .mp3 but that didn't work so I converted them back to the ".aa" extension. How can I listen to these I tunes audio books on my android phone?