Audio Notifications For SmartClient (showcase example) does not work for mozilla firefox

[Isomorphic]

We've got multiple people reporting this is working fine in the latest Firefox. Try disabling any browser extensions you may have active, and clear your browser cache. If you're still having a problem, let us know what OS you are using.

[nGeat]

I need to use the sound notification for my project, and tried to run the example on SmartClient. However, it doesn't work. It did work on an older version of Firefox.
Is there a setting or something I need to do to get this to work?
Here is the link to the showcase example that doesn't make a sound (unfortunately) :
https://www.smartclient.com/smartgwt..._notifications