Flash offers a number of ways to use sounds. You can make sounds that play continuously, independent of the Timeline, or you can synchronize animation to a sound track. Attach sounds to buttons to make them more responsive. Make sounds fade in and out for a more polished sound track.
There are two types of sounds in Flash, event sounds and stream sounds. An event sound must download completely before it begins playing and continues playing until explicitly stopped. Stream sounds begin playing as soon as enough data for the first few frames has been downloaded and synchronizes the sound to the Timeline for playing on a web site.
Adding sounds to a movie involves creating a layer for the sound, assigning the sound, and setting options in the Sound panel of the Frame Properties dialog box.
The sampling rate and degree of compression significantly affect the quality and size of sounds in exported movies. Control the exported quality and size of individual sounds with the Sound Properties dialog box, or define settings for all sounds in the movie in the Publish Settings dialog box.
For an interactive introduction to using sound in Flash, choose Help > Lessons > 6 Sound.