Often, home movies don't have much audio. For example, if you filmed your child snowboarding, there might be nonstop action but nothing to listen to (except the cheering audience). Or, the audio in the background may be distracting if you're videotaping in a noisy area or from a moving car. Fortunately, with Windows Movie Maker, you have two options if you want to make up for the lack of audio: you can add or replace the audio with your own narration of the action, or with music.

Note: If you want background music instead of narration, you can use titles to introduce people or describe settings.

To add narration to your movie

1.	If you have a desktop computer, connect a microphone. Microphones are available from most electronics stores. If you have a portable computer, you can use the built-in microphone. However, you will get a better-quality recording if you connect an external microphone.
2.	Download video from your camera to your computer, and add clips from your collection to your storyboard.
3.	In Movie Maker, click the Tools menu, and then click Narrate Timeline.
4.	If prompted, click OK.
5.	On the timeline, click the clip you want to narrate. You can narrate clips one at a time, or you can narrate the entire movie all at once. If you narrate individual clips, you can rearrange them later and keep your narration synchronized.
6.	Speak normally into your microphone, and adjust the Input level so that the bar is about halfway up when you are speaking.
7.	Under Narrate Timeline click Start Narration.
8.	Speak into your microphone as Movie Maker plays your movie. You can narrate your entire movie at once or just one clip at a time. When you're done narrating, click Stop Narration.
9.	Movie Maker will save your narration as a separate file. In the Save Windows Media File dialog box, type a name for your narration. Then click Save.
10.	Movie Maker adds your narration to your video. If you only narrated part of your video and you want to add narration to other clips, return to step 5.
11.	Click Play in the Preview Monitor to watch your movie and listen to the narration.
12.	If the narration is too loud or too soft in comparison to the movie, right-click the narration on your timeline, and then click Volume. If the audio and narration sound good, you can skip the next step.
13.	In the Audio Clip Volume dialog box, move the slider to the left to make the narration quieter, or move it to the right to make it louder. Then click OK. Return to step 11 to listen to the narration again, and make another adjustment if necessary. If you don't like the way your narration sounds, don't worry—nobody likes to hear their own voice. Just relax and speak in a normal tone, as if you were telling a friend on the phone about your movie. It may take you a few tries to get the timing right so that your narration doesn't go on longer than your movie. If you misspeak often, it might help to write a script that you can read during the narration. To delete narration so that you can re-record it, right-click the narration on the timeline, and then click Delete. You should also delete the narration from the collection.

source- microsoft.com

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