Effective Ways to Reduce Background Noise in iMovie
written by: Rose Smith•edited by: Amy Carson•updated: 5/3/2011
Discover the most effective ways of reducing background noise in iMovie. This tutorial guides you through three ways to reduce noise and improve the sound quality of your iMovies.
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Reducing Background Noise
The new iMovie '11 software allows more control over your audio editing process. You can now adjust or eliminate problem portions of your iMovie audio. What about noise control using older versions of the software? If you're not ready to upgrade, there are some procedures you can use when reducing background noise in older versions of iMovie.
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Manipulate the Soundtrack in iMovie
You can turn down entire snippets of volume in earlier versions of iMovie.
Choose the Timeline Viewer button.
Choose Show Clip Volume Levels. A volume bar will appear in each clip in the Timeline Viewer.
Click a point on the volume bar where you want the audio to change.
Now drag the iMovie marker down to reduce the audio. At the bottom of the edge of the iMovie window, the percentage that you've turned down the volume will be displayed.
To specify how gradually you want the sound decrease to occur, drag the square marker.
You can click the Volume Level bar multiple times to turn down the audio at multiple points during a clip.
While you can decrease the volume in iMovie, sometimes you'll want the actual audio to remain and only remove the background noise. To have more manipulation power of soundtracks in earlier versions of iMovie, you can use Garageband.
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Audio Enhancement Through GarageBand
You can enhance your iMovie soundtrack by filtering it through GarageBand. Having Apple's GarageBand is like having your own audio recording studio on your computer. While it allows you to create music or podcasts, it also allows you to edit a video soundtrack. To reduce background noise through GarageBand in an iMovie you've already put together:
Pull up the clip or portion of the iMovie you want to reduce the background noise in and save it as a separate iMovie file.
Choose Share then click GarageBand.
Adjust the output volume in GarageBand.
Drag the Master Volume slider to the left to lower the output volume.
Before importing back into iMovie, play the clip while viewing the Master Level Meters located above the Master Volume slider to make sure the red dots to the right of the level meters are not lit. These dots–called clipping indicators light up to show the volume level of a project is too high which will cause a distortion known as "clipping" in the exported project.
If the noise in your iMovie clip is not too bad, you should be able to fix it with this method. However, for greatly distorted background noise, you may need to use third-party software.
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Using 3rd Party Software to Reduce Background Noise
You can use software such as the audio editor and recorder, Audacity to remove background noise. Audacity is a free download.
Go to iMovie and export your audio so you can open it in Audacity.
Go to File in iMovie then click Export.
Click CD-Rom on the pull down menu.
Choose Expert Settings.
The next menu, Save Exported File As, gives you several options.
Choose Sound to Wave and set it at 44,100 megahertz. This will give you the standard quality of an audio CD.
Now go back to Audacity and open this file.
Click on Play to hear the audio file.
Search the audio for a space where there is nothing but background noise, such as a pause in the music or person speaking.
Hit the Stop button.
Drag your mouse to highlight the part with only the background noise.
At the top menu in Audacity, click Effect.
Next click Noise Removal.
Select Get Noise Profile.
Next you want to click a portion of audio with sound and background noise.
Then click Effect
Choose Remove Noise to remove the background noise.
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Which of the three applications you use to smooth out any audio problems in your iMovie soundtrack depends on how severe your background noise is. The key to making memorable movies is creating video clips and soundtracks that seamlessly flow to tell the story you want to tell. Becoming an expert at reducing background noise in iMovie is a vital component in creating that continuity.