Hi
I've been looking at this also, but on IOS.
User Media uses the HTML5 text to speech API. Example:
var utterance = new SpeechSynthesisUtterance('Hello world');
window.speechSynthesis.speak(utterance);
This works fine on Safari on iPhone and iPad as standalone javascript. However, once it is compiled via Cordova (PhoneGap) it doesn't work.
It doesn't produce an error, and debug shows that window.speechSynthesis is an object. But the call to .speak doesn't produce sound. I attached it to a user interaction (e.g. click a button to .speech) in case it required user interactivity, still no joy.
I tried using the Cordova TTS plugin instead but it clashed with the Construct 2 audio system.
Once I've looked into this more I'll update this post with my findings.
Good luck!