iMovie
Volume, Fading and Enhancing Audio
As you adjust the volume of a clip in iMovie, its audio waveform changes shape and color to reflect your adjustments. Make sure that the peak sections of the waveform don’t appear yellow, which indicates distortion, or red, which indicates clipping (severe distortion). If you see either red or yellow in your audio waveform, lower the volume until the entire waveform is green. If only part of the waveform is red or yellow and the rest is green, you can adjust the volume of that part of the waveform.
If waveforms don’t appear in the timeline,
click the Thumbnail Appearance button 
in the upper-right corner of the
timeline and select the Show Waveforms checkbox.
Change volume in a clip in the timeline
1. In the timeline, select an audio clip or a video clip with audio.
2. Drag the volume control (the horizontal line across the audio waveform) up or down.
As you drag, the level appears as a percentage value, and the waveform changes shape to reflect your adjustments.
Change the volume of part of a clip
You can select a range in a clip and then change the volume of just that part of the clip. The black horizontal line running through an audio waveform indicates the volume of the audio clip.
Only the volume in the range selection is changed, and iMovie automatically adds a fade at each edge of the selection.
Mute the volume
1. In the timeline, select one or more audio clips or video clips with audio.
2. Click the Volume button to show the volume controls.
Adjust audio over time with keyframes
You can use keyframes to reduce the volume of part of a clip, then raise the volume over time. Keyframes are markers that you can add at specific points in a clip to change the volume at those points. The black horizontal line running through an audio waveform indicates the relative volume of the audio clip.
1. In the timeline, select a clip containing audio you want to adjust over time.
2. In the waveform portion of the clip, move the pointer to the volume control (the horizontal line) at a point where you want to add a keyframe.
3. To add a keyframe, hold down the Option key and click the volume control.
When you hold down the Option key and the pointer is near the volume control, the pointer changes to the Add Keyframe pointer. You can click to add as many keyframes as you want to the clip.
Note: You must add at least two keyframes to your clip in order to adjust the audio over time, because any volume adjustments are made between two keyframes.
4. After you add at least two keyframes, do any of the following:
o Set the volume of the clip at a keyframe: Drag the keyframe up or down.
o Set the volume of the clip between two keyframes: Drag the volume control between the keyframes up or down.
To delete a keyframe, Control-click a keyframe in a clip in the timeline, and choose Delete Keyframe from the shortcut menu.
Fade audio in and outFades are commonly used audio transitions.
Audio fade-ins begin with silence and increase to full volume, and fade-outs
begin at full volume and decrease to silence.
Fade audio in or out
1. To reveal the fade handles, position the pointer over the audio portion of a clip in the timeline.
2. Drag the fade handle to the point in the clip where you want the fade to begin or end.
Dragging a fade handle at the beginning of a clip creates a fade-in, and dragging a fade handle at the end of a clip creates a fade-out.
Correct and enhance audio
iMovie has a number of tools you can use to enhance the audio in your movie. You can boost the volume level of quiet audio in a clip, apply an equalizer preset, and reduce background noise.
Automatically enhance audio
1. In the timeline, select one or more audio clips or video clips with audio.
2. To show the volume controls, click the Volume button.
1. Click the Auto button.
The average volume of the audio in the selection is boosted, and the Auto button becomes highlighted to indicate that automatic enhancements have been applied.
Reduce background noise
You can automatically reduce background noise in a clip without reducing its overall volume. For example, if you recorded a birthday party and a plane flew overhead, you can reduce the volume of the plane to make your movie sound better.
1. In the timeline, select one or more audio clips or video clips with audio.
2. To show the noise reduction controls, click the Noise Reduction and Equalizer button.
3. Select the “Reduce background noise” checkbox.
4. Drag the slider right to increase the amount of background noise reduction, or left to decrease it.
You can adjust the background noise reduction as a percentage of the original clip’s sound (0% represents no background noise reduction, and 100% represents the maximum reduction).
5. Play back the clip to test your adjustment, and then refine the position of the “Reduce background noise” slider.
Apply an equalizer presetiMovie includes a number of equalizer presets, which you can use to
enhance or fix audio in your movie. For example, you can choose an equalizer
preset to enhance vocal quality, or boost bass or treble in a clip.
1. In the timeline, select one or more audio clips or video clips with audio.
2. To show the equalizer controls, click the Noise Reduction and Equalizer button.
3. Click the Equalizer pop-up menu and choose an equalizer preset.
Apply audio effects to clipsiMovie includes audio effects that you can apply to clips to enhance the sound in your movies.
Add an audio effect to a clip
1. In the browser or the timeline, select an audio clip, or a video clip with audio.
2. To show the effects controls, click the Video and Audio Effects button.
3. Click the Audio Effect button, and click the audio effect you want to apply to the clip.
To remove an audio effect, select the clip or range containing the effect, click the Audio Effect button, and click None.
Lower the volume of other clips that play at the same time
When you have background sound or other clips with audio playing at the same time as a clip you want to hear in the foreground, you can automatically lower the volume of the other clips so that they don’t compete with the clip you want to hear.
For example, if you record a section of voiceover audio, you can have iMovie lower the volume of background music and other clips while the voiceover clip plays.
1. In the timeline, select the clip whose audio you want to hear in the foreground.
2. To show the volume controls, click the Volume button.
3. Select the “Lower volume of other clips” checkbox.
The volume of the clips that aren’t selected is lowered.
4. Drag the slider to set the volume of other clips relative to the volume of the selected clip.