How to Remove Hum and Buzz from Audio

To remove hum from audio, open the free Noise Reducer, switch to Music mode, tick Also remove 50/60 Hz electrical hum (auto-detected), then click Reduce noise (Music mode). Preview the result with the Original/Denoised slider and export it as WAV, MP3 or Opus. It's free, there's no account, and it runs in your browser, so your audio never leaves your device.

That covers most cases. The rest of this guide explains what the checkbox does, when it won't be enough, and how to stop the hum from getting into your next recording at all.

What hum and buzz actually are

Hum is a low, steady drone caused by mains electricity leaking into your audio. Mains power alternates at a fixed rate, and that rate depends on where you live:

• 50 Hz in most of Europe, Africa and Australia, and much of Asia, including China and India.
• 60 Hz in North and Central America, parts of South America, and a handful of Asian countries, including South Korea, Taiwan, the Philippines, Saudi Arabia and western Japan.

Hum is rarely a single pure tone, though. It comes with harmonics, which are quieter copies at whole-number multiples of the base frequency (the fundamental). A 50 Hz hum also has energy at 100, 150, 200 and 250 Hz, and a 60 Hz hum at 120, 180, 240 and 300 Hz. If audio frequencies are new to you, think of it as one note with a ladder of fainter notes stacked above it.

Buzz is the same problem with stronger upper harmonics. The energy reaches well up into the midrange, so instead of a soft "mmm" under the recording you hear a harsher, rasping "zzz". Dimmer switches, cheap LED drivers and guitar pickups near an amp tend to produce buzz rather than a clean hum.

Hiss is a different thing. Hiss is broadband, which means it's spread across a wide range of frequencies at once, and it sounds like air or static. Hum is tonal: a pitched sound sitting at a few exact frequencies. The fix depends on which one you have, so it pays to check first.

Why a notch filter beats broadband noise reduction

A notch filter cuts a very narrow slice of the spectrum and leaves everything around it alone. That suits hum, because hum lives on a handful of thin lines. Notch out 60 Hz and its harmonics and you remove the drone while the bass, voice and instruments between those lines stay as they were.

Broadband noise reduction works differently. It estimates a steady noise floor across the whole spectrum and pulls it down. That's right for hiss, and it can lower a hum a little, but it isn't aimed at a few loud, narrow peaks. The spectral gate in the Noise Reducer's Music mode is also capped at about 16 dB of reduction so it can't hollow out a mix. A strong hum can sit above that cap.

That's why the hum checkbox exists. When you tick it, the tool looks at the noise profile of your file, compares how much energy sits on the 50 Hz harmonic series against the 60 Hz series, and picks the stronger one. It then applies very narrow notch filters (Q = 35, where a higher Q means a narrower cut) at the fundamental and harmonics 2 to 5. If it doesn't find a clear hum, it notches nothing, so ticking the box on a clean file doesn't change it.

What you'll need

• A file you already have, in MP3, WAV, FLAC, M4A, AAC, OGG, Opus or WebM audio. Safari can't decode OGG or Opus, so use another browser for those.
• A file up to 100 MB and 12 minutes long. Trim a longer recording first with the Audio Cutter.
• Headphones. Hum is low, and laptop speakers often can't reproduce 50 or 60 Hz at all, so you may not hear whether it's gone.

How to remove hum from audio, step by step

1. Confirm it's hum. Drop the file into the Spectrogram. Hum shows up as a thin, steady horizontal line at 50 or 60 Hz that runs straight through pauses, often with fainter lines stacked above it at the harmonics. Hover over the line to read its frequency. How to Read a Spectrogram covers the settings that make it easiest to see.

   

2. Open the Noise Reducer and add your file. Drag it onto the drop zone on the Noise Reducer page, or click to choose it.

3. Choose Music. Music mode uses spectral processing rather than AI and is the only mode with the hum control. It keeps the full frequency range and stereo, and it doesn't download a model.

4. Tick the hum checkbox. It's labelled Also remove 50/60 Hz electrical hum (auto-detected) and is off by default. You don't need to know whether your hum is 50 or 60 Hz; the tool works it out.

5. Click Reduce noise (Music mode). Processing runs in a background worker and shows a percentage, the current stage and an estimate of time left. A long file takes a while.

6. Preview and set the mix. Press play and listen. The slider runs from Original to Denoised and starts at 75%, shown as "Noise reduction: 75%". Drag it to 100% for the full effect, or pull it back if the result sounds thin. At 0% you hear the untouched original. Changes apply live and carry through to the export.

7. Export. Pick WAV (the default), MP3, or Opus where your browser supports it (not Safari), then click the export button, for example Export WAV. Reset File clears everything if you want to start again.

Speech recordings: when Voice mode handles it

If the recording is someone talking, such as a podcast, interview or voice memo, try Voice mode as well. It uses GTCRN, a small AI speech model, and works by keeping the voice and suppressing everything else. A steady hum is "everything else", so Voice mode will often take it out along with room noise, even though it has no hum checkbox.

There are trade-offs. The model is about 0.5 MB, downloaded once and then cached, and processing isn't instant. The model processes audio at a 16 kHz sample rate, so the output is mono and limited to the speech band (roughly below 8 kHz), which is fine for spoken word but not for music. The tool warns you not to run songs through it, and that warning is worth taking seriously: instruments and reverb get stripped along with the noise. How AI Noise Reduction Works explains why.

For hiss, traffic, fans and other general noise, or for cleaning the soundtrack of a video, How to Remove Background Noise from Audio is the better guide. It also covers how to remove background noise from video by working on the extracted audio.

When the hum is still there

You can still hear a buzz. The notches stop at the fifth harmonic, which is 250 Hz for 50 Hz hum and 300 Hz for 60 Hz hum. A harsh buzz has energy well above that, and those upper harmonics aren't notched. The spectral gate may lower some of them, but a bright, rasping buzz may only be partly removed. A small, gentle treble or presence cut with the Equalizer can soften what's left.

The hum drifts or comes and goes. The notches sit at fixed frequencies and the detection reads a steady noise profile. A generator whose pitch wanders, or a fridge compressor that cycles on and off halfway through, doesn't match that, and you may get partial removal or none. Cut the worst section into its own file with the Audio Cutter and process it separately, or try Voice mode if it's speech.

The music sounds slightly thinner. In a quiet acoustic track, a notch at 100–300 Hz can touch the body of a guitar or a low voice. The notches are narrow, so this is usually subtle, but if you hear it, pull the mix slider back from 100% until the hum is low enough and the instrument sounds right again.

You want an EQ fallback. The Equalizer is a 6-band graphic EQ with fixed bands, so it can't make a narrow notch. On a voice recording with little wanted low end, pulling its 80 Hz low shelf down will tame a 50 or 60 Hz fundamental, but it also thins out any bass, so treat it as a blunt fallback rather than a hum filter. Parametric vs Graphic EQ: The Difference explains why a parametric notch is the precise tool for this.

It got quieter overall. Taking out a strong hum removes real energy from the file, and the result can feel a touch lower in level. Run it through the Volume Normalizer to bring it back up.

Stop hum at the source

Removing hum after the fact always costs something. Keeping it out of the recording costs nothing.

Break the ground loop. A ground loop happens when two pieces of connected gear reach electrical ground by different paths, for example a laptop on its charger plugged into an audio interface that's powered from another outlet. The small current flowing around that loop becomes hum. Things to try:

• Plug everything in the chain into one power strip.
• As a test, unplug the laptop charger and record on battery. If the hum disappears, the charger, or a ground loop through it, is the culprit.
• Use balanced cables (XLR or TRS) between gear that supports them. Balanced connections reject hum that unbalanced ones pick up.
• Keep audio cables away from power cables. If they have to meet, cross them at right angles; it's a minor extra precaution next to balanced cabling.
• A DI box or a dedicated ground-lift switch can break a loop safely. Never remove or tape over the safety earth pin on a mains plug. That pin is what protects you if a fault puts mains voltage on the metal casing.

Watch the lighting and power. Dimmer switches and cheap LED or fluorescent drivers put out a lot of buzz. Switch them off, or turn the dimmer to full, while you record.

Mind the cheap and bus-powered gear. Some budget USB-powered interfaces pick up noise from the computer's power supply. A different port, a good-quality powered hub (a cheap one can add its own whine), or running on battery can help.

Turn the guitar. Single-coil pickups act like antennas for hum from amps, monitors and computers. Move away from screens and turn slowly until the hum drops; there's usually a quieter angle.

For the rest of a clean setup, see Record Clean Vocals at Home on an Audio Recorder and Mic Placement for Clean Voice Recordings. If you're recording speech regularly, How to Record a Podcast With an Audio Recorder covers the whole session.

After the hum is gone

Once the drone is out, a spoken recording often benefits from a little shaping. How to EQ a Podcast Voice for Clear Speech shows where to cut and boost, and the Audio Enhancer can add polish in one pass. For more step-by-step cleanup and recording walkthroughs, browse the Audio How-To Guides.

Frequently asked questions

Is mains hum 50 Hz or 60 Hz?

It depends on where the audio was recorded. Most of Europe, Africa and Australia and much of Asia use 50 Hz mains power, while North and Central America, parts of South America, and a few Asian countries such as South Korea, Taiwan, the Philippines and western Japan use 60 Hz. Hum also has harmonics at multiples of that frequency, such as 100 and 150 Hz or 120 and 180 Hz. The Noise Reducer's hum option detects which series is present, so you don't need to know in advance.

Can you remove hum from audio for free?

Yes. The Vocal Cut Noise Reducer is free, needs no account, and runs in your browser, so your audio never leaves your device. Choose Music mode, tick the option to remove 50/60 Hz electrical hum, and process the file. It applies narrow notch filters at the detected hum frequency and its harmonics up to the fifth, then exports WAV, MP3 or Opus.

Why does my recording hum when my laptop is charging?

That's usually a ground loop. When a charging laptop and an audio interface or mixer reach electrical ground through different outlets, a small current flows around the loop and shows up as hum. Try running the laptop on battery while you record, or plug every piece of gear into the same power strip. Balanced XLR or TRS cables also help reject hum.

Will removing hum affect the bass or the music?

Usually only slightly. Hum removal with narrow notch filters cuts thin slices at the hum frequencies and leaves the audio between them untouched, so most music sounds the same afterwards. In quiet acoustic recordings, notches between 100 and 300 Hz can slightly thin a low instrument or voice. If you hear that, pull the Original/Denoised mix slider back so less of the processed signal is used.

Can AI remove hum from audio?

For speech, often yes. An AI speech model like the one in the Noise Reducer's Voice mode keeps the voice and suppresses everything else, which often includes a steady hum. It isn't suitable for music, though, because it strips instruments and reverb too, and its output is mono speech-band audio. For music, a targeted notch filter is the better tool.