How to Remove Hum and Buzz From Audio (50Hz vs 60Hz Explained)

You finish a recording, play it back, and there it is: a low, steady drone sitting under every word. Sometimes it is a soft hum you only notice in the pauses. Sometimes it is a harsh, nasal buzz that makes the whole take sound cheap.

Both usually come from the same place: the electricity running through the walls, the cables, and the gear around your microphone. The good news is that this kind of noise is very predictable, which makes it one of the easier problems to fix, both while recording and after the fact.

This guide explains where hum and buzz come from, why the 50Hz vs 60Hz difference matters, how to stop it at the source, and how to remove hum from audio online when the recording is already done. It also covers what cleanup can't fix, so you know what to expect.

What Hum and Buzz Actually Are

Mains electricity is alternating current. It changes direction many times per second, and that rate is called the mains frequency (or utility frequency). When some of that electrical energy leaks into your audio path, you hear it as a tone at that frequency.

50Hz vs 60Hz: it depends on where you record

There are two mains frequencies in use around the world:

• 60Hz in the United States, Canada, Mexico, Brazil, and much of the rest of the Americas, plus a few places in Asia such as South Korea and Saudi Arabia.
• 50Hz across most of the rest of the world, including Europe, the UK, China, India, Australia, and Africa, and some South American countries such as Argentina and Chile.

Japan uses both. Eastern Japan, including Tokyo, runs at 50Hz, while western Japan, including Osaka and Nagoya, runs at 60Hz.

So a recording made in London hums at a slightly lower pitch than one made in New York. That matters when you fix it by hand, because you need to target the right frequency.

Hum vs buzz

• Hum is a low, smooth drone at the mains frequency itself, 50Hz or 60Hz. It is often caused by a ground loop.
• Buzz is harsher and more nasal. It usually sits at double the mains frequency (100Hz or 120Hz) with more tones stacked above it, called harmonics. It typically comes from power supplies or light dimmers.

In practice, real recordings often contain the base tone plus a whole series of harmonics, which is why a single cut at 50Hz or 60Hz rarely makes the noise disappear.

Common Causes of Hum and Buzz

• Ground loops. When two pieces of connected gear, such as a computer and an audio interface or mixer, are plugged into different outlets, small voltage differences between their grounds can push current through the audio cable's shield. That current becomes hum.
• Unbalanced cables. Guitar cables and RCA leads have no built-in noise rejection, so they pick up interference, especially over long runs or when laid next to power cords.
• Laptop chargers. Many people hear hum appear the moment they plug a laptop in and disappear when it runs on battery. Some chargers also add their own whine.
• Dimmer switches. Traditional dimmers chop up the mains waveform to lower the brightness, and that chopping radiates buzz into nearby cables. If the buzz stops when the lights go off, you have found the culprit.
• Air conditioners, fridges, and fans. These add a mix of mechanical rumble and electrical hum from their motors, which is why AC noise in a video often sounds like a hum and a hiss at the same time.
• Fluorescent lights and cheap power strips. Both are common sources of buzz in home studios and offices.

How to Stop Hum While Recording

Fixing hum at the source always beats fixing it later. Before your next session, try these:

1. Unplug one thing at a time. Record a few seconds of silence, then disconnect devices one by one until the hum stops. That tells you which connection to fix.
2. Run the laptop on battery. If the hum disappears when the charger is out, record on battery or plug everything into the same outlet or power strip.
3. Use balanced cables. XLR and TRS balanced connections are designed to cancel interference picked up along the cable. Keep cable runs short where you can.
4. Keep audio cables away from power cables. If they have to cross, cross them at a right angle instead of running them side by side.
5. Turn off dimmers and fluorescent lights in the room, or switch them to full brightness, while you record.
6. Use a ground lift or isolation transformer on a DI box or interface if your gear has one. Never remove the ground pin from a power plug. It is unsafe, and audio equipment manufacturers warn against it.
7. Switch off the AC for the few minutes you need a clean take.

How to Remove Hum From a Finished Recording

If the recording is already done, there are two main approaches.

Option 1: Notch filters and EQ

Because hum sits at known frequencies, you can cut those frequencies with very narrow notch filters. In Audacity, for example, the Notch Filter effect lets you set a frequency and a width.

1. Find out whether your hum is at 50Hz or 60Hz. A spectrum view in your editor will show a tall peak.
2. Apply a narrow notch at that frequency.
3. Repeat for the harmonics: 100Hz, 150Hz, 200Hz for 50Hz hum, or 120Hz, 180Hz, 240Hz for 60Hz hum.
4. Add a gentle high-pass filter below the lowest part of the voice if rumble remains.

This works well when the hum is a clean, steady tone. The downsides are that it takes time, every notch also removes a slice of the voice, and it does nothing for hiss, fans, or other broadband noise mixed in with the hum. Many editors also offer dedicated hum removal plugins that automate the harmonic notches, which is a good choice if you already work in one.

Option 2: AI cleanup in your browser with NoiseWipe

If you would rather not hunt for frequencies, an AI speech enhancement tool can treat hum, buzz, and hiss together. NoiseWipe runs in your browser, so there is nothing to install.

1. Open the background noise removal page and drop in your file. NoiseWipe accepts MP3, WAV, and M4A audio, plus MP4, MOV, WebM, and MKV video, so you can remove AC noise from video without separating the audio first.
2. Wait for processing. The audio is cleaned with an AI speech enhancement model (DeepFilterNet) that keeps speech and suppresses what isn't speech, whatever its frequency.
3. Listen to the free 30-second cleaned preview. No signup is needed. Pick the section where the hum is loudest and use headphones, because low hum is easy to miss on laptop speakers.
4. If it sounds right, download the full file. Downloads start at $0.99 per file, with hour packs and subscriptions if you clean recordings regularly.

The same workflow covers hiss, so if you came here to remove hiss from audio online, the steps are identical.

What Cleanup Can and Can't Fix

Hum is one of the friendlier kinds of noise, but there are honest limits.

Usually fixable

• Steady mains hum at 50Hz or 60Hz under speech.
• Buzz and harmonics from chargers, dimmers, and power supplies, as long as the voice is still clearly audible.
• AC and fan noise mixed with electrical hum.
• Hiss from high gain or a quiet source.

Hard or not fixable

• Hum louder than the voice. If the drone completely covers parts of the speech, there is not enough voice left to recover.
• Music recordings. NoiseWipe is built for speech. On a song or an instrument recording, it may treat the music itself as noise, so a careful notch filter is the safer option there.
• Crackle and distortion. Intermittent pops from a faulty cable or a clipped signal are damage to the waveform, not steady noise, and cleanup won't restore them.

The 30-second preview is the quickest way to find out which group your recording falls into before you pay anything.

Related guides

• How to remove background noise from a Zoom recording
• How to remove background noise from a Voice Memo on iPhone
• How to remove wind noise from GoPro video

FAQ

How do I remove hum from audio online?

Upload the file to a browser-based tool such as NoiseWipe, listen to the cleaned 30-second preview, and download the full file if it sounds right. There is no software to install and no need to find the hum frequency yourself.

Is my hum 50Hz or 60Hz?

It depends on where it was recorded. Most of the Americas use 60Hz, while Europe, most of Asia, Africa, and Australia use 50Hz. Japan uses 50Hz in the east and 60Hz in the west. A spectrum view in any audio editor will show the peak.

Why does a notch filter at 50Hz or 60Hz not remove all the hum?

Hum usually includes harmonics at multiples of the mains frequency, such as 100Hz and 150Hz, or 120Hz and 180Hz. Buzz in particular is strongest at double the mains frequency. You need to notch each harmonic, or use a tool that removes the noise as a whole.