01 — On a Mac
Drag it straight out of Voice Memos
If Voice Memos is turned on in iCloud, anything recorded on your iPhone is already sitting in the Voice Memos app on your Mac. That makes this the easiest route by a wide margin, and it is worth turning that sync on if you have not.
Open Voice Memos on the Mac, find the recording, and drag it out of the list onto your desktop or into a folder. You now have an .m4a file, which iMovie reads natively.
Then open your iMovie project and drag that file onto the timeline, below your video clips. Dropping it in the audio area rather than onto a clip keeps it as an independent track you can move without disturbing the picture.
02 — The alternative on Mac
Import through the media browser
If you would rather not drag between windows, use File and then Import Media in iMovie, and navigate to wherever you saved the exported recording.
The recording lands in your project media alongside your video. Drag it down to the timeline when you are ready to place it, which lets you import several memos at once and decide the order afterwards.
03 — On an iPhone or iPad
Export first, then import
iMovie on iOS cannot reach inside the Voice Memos app, so start by getting the recording out. Open Voice Memos, tap the recording, tap the more button, tap the share button, scroll down and tap Save to Files. Choose a location you will remember and tap Save.
Now open your iMovie project, move the playhead to where the audio should start, and tap the add button. Choose Audio, then browse to your saved file rather than to the built-in soundtracks.
The memo drops in as its own audio track at the playhead position, ready to be trimmed and moved.
Place the playhead before you add the audio. Moving a long audio clip along an iOS timeline afterwards is fiddlier than simply starting it in the right place.
04 — Once it is in
Trimming and balancing the track
Drag either end of the audio clip to trim the dead air at the start and finish. Almost every phone recording has a second or two of fumbling at each end, and removing it is the single biggest improvement you can make in the edit.
If the memo is competing with sound from your video clips, lower the volume on the video rather than raising the memo. Pushing a phone recording louder tends to bring the room up with it.
Add short fades at the beginning and end of the audio clip. An abrupt start to a spoken track is noticeable in a way that a quarter-second fade never is.
05 — If it sounds rough
What iMovie cannot fix
iMovie has a noise reduction control and an equaliser, and for a lightly noisy recording they are enough. What they will not do is rescue a memo recorded across a room, or one with heavy traffic behind it.
For those, treat the audio before it reaches iMovie. Running the file through a noise reducer first gives you a clean track to cut against, and means the edit does not have to be redone if you change your mind about the processing.
Take the room out of the recording
Reduce background noise, then bring a clean track into iMovie.
Give the voice track the quality the picture deserves.
Enhance and export with Hilite.