Sadly, no. Ruby is not normally used for client side apps, so I didn't decide to spend time on that (like wit's new official library). You could easily modify the library to send audio files, though. Sadly, you still have the problem of getting speech from the user, normally a somewhat difficult process that this gem alone couldn't take care of.
But, if you'd like to send a PR for sending audio files, I'd very much love to accept it.