How to Control Audio
Adding audio should be the last thing you do. Each and every time you add or change the video through inserting transitions, adding titles, adding movie video, or adding images you change the structure of the movie. Your audio needs to follow the structure of your movie.
There are two types of audio that you can add to a movie: Voice Over and Music. Both audio formats are placed in the Audio/Music layer of the Timeline.
Music is easier to deal with. All you need to do is drag a music file—such as an MP3, WAV, or WMA file—from your collection into the Audio/Music layer. You can use the resize handles on either side of the audio to force how long the audio track is.
The Voice Over is slightly different. You select where you want the Voice Over to start in your movie. You then have to select the Narrate Timeline microphone on the Timeline, which opens a new window with a Start Narration and Stop Narration button.
To add a Narration you must have a microphone. Select the Start Narration button and the movie begins playing. Just start talking; the microphone picks up everything you're saying. Keep talking until you're finished; then press the stop button. A window appears and asks you to save the Narration as a WMA file. The file is automatically added to your movie.
There are some common features between Narration and Music. The first is that you can Fade Out any music at the of the audio track. Audibly this is more pleasant than a straight cut. Second, you can control how loud the audio is