Feature suggestions should be posted to the uservoice
https://twitch.uservoice.com/forums/310213-developers
But the issue here is likely to be a device issue.
Whilst iOS might be straight forward due to limited list of devices and software combinations, android is a utter mess of platforms, phones and, OS versions combinations.
The best solution here is for any sound to be embedded in the stream, as a browser source for the streamer, as then everyone, even non extension enabled platforms get the sound