Thank you for the warning,
Stan001. So you see: it is easy to get just some sound somehow, but to get it safe, at the right time, portable between browsers, and without side effects like the one you describe -- this is a much more difficult task which I did not solve yet.
And to be true: this is not very high on our priority list, as introducing sound is a very big change to the game.
Now if we would start with introducing sound, this means a lot of speaking, female moaning (mermaids welcome

), background sounds and music has to be produced and post-produced and allocated to the scenes. not to mention the copyright issues. So, we don't plan to open this can of worms now. The doorbell was just a joke for the beginning.
Thank you anyways for your effort. If you manage to find a way to let the doorbell ring without unpleasant side effects, at least for Firefox, Internet Explorer and Safari, let me know, and we might just add this to a future release. But for the doorbell only.
Thank you, and Cheers!
qbv8