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Watch the tutorial
Step 1: Add the Lowpass effect
Open the Effects panel and search for Lowpass. You will find it under Audio Effects > Filter and EQ. Drag it onto the audio clip.
Faster with BetterFX: skip the Effects panel. Press your BetterFX shortcut, type the first letters of Lowpass and press Enter to apply it to the selected clip. Get BetterFX
Step 2: Open the audio clip in Effect Controls
Select the audio clip and open Effect Controls. Under Lowpass you will see one setting, Cutoff. A low pass filter lets low frequencies through and removes the high ones. The lower the cutoff, the more muffled the sound.
First, set Cutoff to 20000 Hz so that no frequencies are cut off at the start. The clip should still sound normal.
Step 3: Keyframe the moment before the dive
Move the playhead to the point just before the person jumps into the water. Click the stopwatch next to Cutoff to create a keyframe at 20000 Hz.
Step 4: Muffle the sound underwater
Move forward to the point where the camera goes underwater and change the Cutoff to around 500. Premiere Pro adds a second keyframe automatically. Play it back. The sound now drops from normal to muffled right as the splash happens.
Step 5: Bring the sound back above the surface
When the person comes back up, move the playhead to where they are almost at the surface and add a keyframe with the button in Effect Controls (the diamond next to Cutoff). Then move to the point where the camera is above the water and set Cutoff back to 20000 again. The audio opens up as the head breaks the surface.
Step 6: Fine-tune the keyframes on the timeline
To see what you made, right-click the audio clip on the timeline, go to Show Clip Keyframes, then Lowpass and choose Cutoff. The keyframes now appear on the clip, and you can drag them around to change the timing.
Tips
- Match the picture. Place the keyframes exactly on the frame where the camera goes under for the most convincing result.
- Try different cutoffs. Around 500 Hz sounds deep underwater, while a higher value sounds more like a shallow pool.
- Add distance. For other muffled sounds, see how to make audio sound distant.
FAQ
What does the Lowpass effect do?
It removes high frequencies and keeps the low ones, which makes audio sound muffled, like it is heard through water or a wall.
Why start the Cutoff at 20000?
At 20000 Hz almost nothing is removed, so the clip sounds normal until your first keyframe.
Can I use this effect on any clip?
Yes. Apply it to any audio, then keyframe the Cutoff to start and end the effect.
Add splashes and ambience on top of your muffled audio with the Sound Effects Pack Mini.
