In this guide
In iMovie on Mac, select the timeline clip, open Noise Reduction and Equalizer, enable Reduce background noise, and adjust the slider while listening. Compare the result with the original and check quiet speech before exporting.
To reduce background noise in iMovie on Mac, select the audio or video clip in the timeline, click the Noise Reduction and Equalizer button, and enable “Reduce background noise.” Adjust the slider, listen to the clip, and compare the result with the untreated version before exporting.
Noise reduction changes the sound inside the selected clip. It does not necessarily remove a separate music track, isolate one person or repair every noisy recording. Start with a small adjustment and listen to quiet words as well as the gaps between them.
Reduce background noise in iMovie on Mac
- Keep the original. Work from a copy of the project or source where practical, so you can compare your edits with the recording you started with.
- Select the clip. Open the movie and select the audio clip or video clip with audio in the timeline. Select the actual clip containing the noise, not an unrelated music layer.
- Open the controls. Click the Noise Reduction and Equalizer button above the viewer, then select Reduce background noise.
- Adjust and listen. Drag the slider right for more reduction or left for less. Play a section with speech and a quieter pause. Apple's iMovie audio guide describes the control and its percentage scale.
- Compare and refine. Toggle the checkbox to compare with the untreated clip at a similar listening level. Check consonants, breaths and quiet endings; if speech becomes watery, thin or broken, reduce the amount.
- Check the exported movie. Listen to the finished file on headphones and a small speaker. Verify the sound, picture sync and beginning and end of the edited section.
The slider's percentage is a control setting, not a measured percentage of noise removed. Results depend on the recording and the overlap between wanted and unwanted sound. A maximum setting is not automatically the clearest result.
Choose the right fix for the sound
| What you hear | Starting point | Limit to check |
|---|---|---|
| Steady fan or hiss in the clip | Test iMovie's background-noise slider gently. | Compare quiet speech and ambience before and after processing. |
| Music on its own timeline layer | Lower, mute or remove that separate music clip. | Noise reduction is not needed just to change a separate layer. |
| Music mixed with dialogue | Look for the original voice recording; if unavailable, test a voice-isolation estimate. | Isolation can leave music or change words and is not the original microphone track. |
| Echo or doubled voice | Check duplicate tracks and monitoring first. Listen to the exported movie separately. | Room reflections and playback echo have different causes; one slider is not a guaranteed repair. |
| Clipped or distorted speech | Return to a cleaner take or original source if one exists. | Reducing noise does not restore information lost to clipping. |
If background music is separate and you want it to play more quietly under narration, iMovie's lower-volume-of-other-clips control is a different operation from reducing noise within one clip. Select the foreground clip and verify the balance during speech and pauses.
What about iMovie on iPhone?
The steps above describe iMovie on Mac. Apple's iPhone audio instructions cover clip volume, mute and fades; they do not describe the Mac noise-reduction slider. Muting a clip silences its speech too, so use it only when you do not need that clip's audio.
For supported videos recorded with Spatial Audio, Apple's Photos app offers Audio Mix controls on compatible devices. Availability depends on the source and device; compare the result and keep the original. The iPhone video noise guide covers that workflow and other options.
If the noise is mixed with the voice
Keep the unprocessed audio and try a short representative section first. The Saturalabs voice isolator estimates a described voice from supported audio or video; it uploads the source for processing and AI downloads require an account and sufficient credits. The result can retain noise or alter speech, so compare it with the original. It returns audio, not an edited iMovie project or finished video.
Import the chosen result into the editor, align it with the original source position, mute the audio being replaced and check sync at the beginning and end. If you processed a trimmed excerpt, place it back at that excerpt's original position. The audio replacement guide explains the checks in more detail.
Common questions
Does iMovie remove all background noise?
No. The Mac control reduces noise to a degree that depends on the recording and settings. Always check whether it also changes wanted speech.
Where is the noise reduction button?
On Mac, select an audio clip or video clip with sound in the timeline, then open Noise Reduction and Equalizer above the viewer. If no controls appear, confirm a suitable clip is selected.
Can I remove music without removing speech?
If music is a separate clip, adjust that clip. If it is mixed with speech, an isolation tool may help but cannot guarantee a clean separation.
Why does my voice sound distorted afterward?
Too much processing can affect quiet speech and consonants. Lower the reduction amount, toggle it off for comparison, and check the original for distortion that was already recorded.