Hello, this is a direct quote from the Apple iMovie web site:
Plus, you can add AIFF, WAV, CD and MP3 sound files to your movie soundtrack simply by selecting them and dropping them into the Timeline. Naturally, you can adjust the duration (fade in, fade out) and volume of your audio clips.
The problem I am having is I can not import a .wav file. I am trying to add the Star Trek transporter sound into a movie, and when I export it to an .aif file, it gets corrupted somehow and adds extra noise at the end of the sound. When I try to import it as a .wav file, the file does not darken so I can not choose it. Please help.