I believe there is an outstanding bug on iOS where audio plays back distorted. We’ve seen this occur in PlayCanvas apps.
The problem seems to be that iOS / Safari, plays sound back with the wrong sample rate. This is dependent on other apps or tabs. The crappy solution is to refresh the page, which seemed to work when we were testing.
I’m not sure there is much that we can do to fix this, though if anyone has ideas for a work around we’re happy to fix it.
There was a recent fix we deployed in the engine that possibly fixes this issue. If you could re-publish your app again and test it on your device it’d be great.