Dynamic Sounds Across Scenes
Scripted sounds don't work well with scenes. Whenever a scene change occurs, all objects on the stage are automatically removed, including movie clips that might have sounds attached to them. The result is orphaned sound objects that will continue to play, if already started, but that will not respond to further scripted commands.
One of Flash's glitches (or features, depending on your perspective) is that movie clips that are also attached dynamically do not get removed during a scene change. Instead, they hover above everything until they're purposefully removed.
This glitch/feature can be used to solve the problem of orphaned sound objects. Sounds can be attached to dynamic movie clips, making them impervious to scene changes. Blank movie clips are best for this purpose: That way they are invisible and positioning is not important.
To attach a movie clip symbol dynamically, set its Linkage Properties to Export and use the attachMovie() action.