This is the only solution within iOS 6 that I've found so far:
Youtube video showing how it works
The source can be found here:
GitHub Repository Link
It uses an workaround by using iOS6's camera plugin's record features to record video and audio and uploads that to the server. Then FFMPEG crunches the video and extracts the audio as a .wav file.
With all the limitations and unfinalized HTML 5 specs, I think this is the only way for it to work. I hope this helps.