When Matthew Ammann was following the base AS3 tutorial, he wrote a new class, SoundObject, to manage all the sounds inside his game.
He’s posted this class on his blog so that everyone can use it — and on top of that, he’s written a great tutorial to explain how it all works!
This makes it easy to mute songs, and switch between different tracks from different screens.
Check it out here. Thanks, Matthew!

[...] Ammann — who wrote the previously-mentioned SoundObject class — has written a game called Robot Saga: [...]
Great Class! It gratly helped me build my own
I do want to add to the tutorial though that it is important that you cannot call any of the functions of the SoundObject in the DocumentClass, this is because of the preloader ( DocumentClass is processed in frame 1 and the SoundObject in frame 2 ). It got me frustrated for at least a few hours
Ooh, good point. Thanks Erik!