In this approach, you import the audio file into the Flash Timeline. Then, you use the waveform display in the Timeline to find where each word begins and ends. You then perform your animation (to reveal text, for example) in the frames that correspond to the appropriate word in the audio. One drawback is that for long audio files, locating the beginning of each word or sentence can be tedious.
In the Timeline, select the layer you want to add the sound to and then drag the sound from the Library to the Stage. The sound waveform appears in the Timeline in the layer you selected. Make sure to add frames to the timeline to accommodate the entire length of the sound. (The number of frames is the Frames-per-Second setting times the number of seconds of the sound.)
Now in other layers, line up your animations or whatever you like to display the appropriate text at the appropriate word in the sound file. For example, you can present the written text by first covering each word or phrase of it with an opaque rectangle. Make sure that the rectangle's color matches the background color. Then, you smoothly change its opacity from 100% to 0% at the appropriate time.
These resources provide more information about working with sound and timing in Flash Pro.
- Help: Using Sounds in Flash