For anyone who is experiencing sound issues in Chrome, there is a workaround. I use the browser a lot and it's been making my Ubuntu experience very irritating lately. Videos have been impossible to listen too and even using Gmail has been irritating with a background 'static heartbeat' that runs continually.
It doesn't affect Firefox, so that's an option, but if you depend on Chrome like me... here's the fix:
1. Go to chrome://plugins/
2. Expand the Details (click plus sign on right side)
3. Disable the Pepperflash plugin
It looks like the issue is documented as a chromium issue in a number of places e.g. here and here.