How to remove hum from audio
- Drop your file. Drop an audio or video file (up to 10 minutes) onto the tool, or press Try a sample.
- Pick the settings. Noise removal strength, hum removal (Auto finds 50 or 60 Hz) and a loudness target: Podcast (-16 LUFS), YouTube (-14 LUFS) or Keep.
- Clean and compare. Press Clean audio. The first run downloads the noise model once (about 17 MB). Then switch between Before and After with A and B while it plays.
- Download. Save a WAV, a compressed M4A (or Ogg in Firefox), or for video, the same video with the cleaned audio.
Why hum is 50 or 60 Hz
Electrical hum comes from the mains supply leaking into the audio, usually through a ground loop, an unbalanced cable or a nearby transformer. It sits exactly on the mains frequency and its multiples. That frequency depends on where you are (list by country):
| Mains | Where | Hum lines |
|---|---|---|
| 60 Hz | United States, Canada, Mexico, Brazil, Saudi Arabia, western Japan | 60, 120, 180, 240 Hz… |
| 50 Hz | UK and Europe, Pakistan, India, Australia, most of Africa and Asia, eastern Japan | 50, 100, 150, 200 Hz… |
How the hum removal works
With hum removal on Auto, the tool measures how far the 50 and 60 Hz lines and their first harmonics stand above the sound a few hertz either side, across up to 20 one-second slices, and picks the one that is really there. It then applies eight narrow notch filters, each 2 Hz wide, on the fundamental and its harmonics (up to 400 or 480 Hz). A notch that narrow takes the hum line out by more than 30 dB while a voice harmonic 5 Hz away loses less than 0.2 dB. The buzzy upper harmonics above that are handled by the noise model in the same pass.
If Auto reports "none found" but you can hear hum, set 50 Hz or 60 Hz by hand. If you only want hum gone and nothing else, set Noise removal to 0. For fans, traffic and room noise, see the noise remover.
Fix it at the source next time. Plug the computer and audio interface into the same power strip, use balanced (XLR or TRS) cables, and keep audio cables away from power bricks. A cheap ground-loop isolator fixes most laptop-plus-mixer hum.
Questions
How do I remove hum and hiss from a recording?
Drop it onto the tool above with Hum removal on Auto and Noise removal around 80. The notch filters take out the hum lines and the noise model takes out the hiss in the same pass.
How do I get rid of 50 Hz hum?
Choose 50 Hz under Hum removal (or leave it on Auto) and press Clean audio. The tool cuts 50 Hz and its harmonics at 100, 150, 200 Hz and up, each with a 2 Hz-wide notch.
How do I remove 60 cycle hum after recording?
60-cycle hum is 60 Hz mains hum, common in North America. Choose 60 Hz (or Auto). Because the cuts are only 2 Hz wide, the voice around them is left alone, unlike a high-pass filter that also thins the voice.
Is a notch filter better than a high-pass filter for hum?
For hum, yes. A high-pass filter removes everything under its cut-off, including the body of a low voice, and still leaves the harmonics at 100-480 Hz. Notches remove only the hum lines.
How do I get rid of electrical hum in my recording set-up?
Common causes are ground loops (gear on different outlets), unbalanced cables and cables running next to power supplies. Use one power strip, balanced cables, or a ground-loop isolator. For recordings you already have, use the tool above.
Can it remove hum from a video?
Yes. Drop the video, clean it, and download the video with the cleaned audio; the picture is copied untouched.
Is my audio uploaded anywhere?
No. The file is decoded, cleaned and encoded in this browser tab. The only downloads are the noise model and its WebAssembly engine, which come from this site and stay in your browser's cache. You can disconnect from the internet after the model has loaded and it still works.