You are at least half right
I have checked on different versions
Firefox 25.00.1 (latest I think) sounds odd - like it is from the bottom of the sea in places - but works.
a slightly earlier version on another PC does not work at all.
I think the lesson is - if it doesn't work for some people - try and different browser or update it ;)
I hope I helped and haven't just reported a unique problem to me.

Thanks Februs