Get rid of the steady buzz from ground loops, cheap cables and lighting. The tool finds the hum in your recording, then removes the 50 or 60 Hz fundamental and its harmonics with narrow notch filters that leave voices and music almost untouched. Listen to the cleaned audio, the original, or just the hum that is being removed.
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Analyzing…
Notch filtersBeforeAfter
Mains frequency
Hz
Fine-tune if the hum is slightly off (generators, tape speed).
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How to use the Hum Remover
Open your recording by dropping it on the box or clicking to choose. A demo voice clip with 60 Hz hum is loaded so you can hear how it works.
Check the detection. The tool reports whether it found 50 or 60 Hz hum and sets the exact frequency and number of harmonics.
Press Play preview and switch between Cleaned, Original and Removed hum only. If you hear voice in the removed hum, raise the Q or lower the strength.
Adjust if needed: add harmonics if buzz remains, or pick 50 Hz or 60 Hz manually.
Choose WAV or MP3 and press Download cleaned audio.
Hum frequencies and their harmonics
Hum appears at the mains frequency and at its whole-number multiples. These are the frequencies the notches target:
Countries using 60 Hz include the United States, Canada, Mexico, most of Central America, parts of South America, South Korea, Taiwan, the Philippines and western Japan. Most other countries use 50 Hz.
How the notch filters work
A notch filter removes a narrow band around its center frequency. Its width is set by Q: bandwidth = frequency ÷ Q, so a Q of 30 removes a band about 2 Hz wide at 60 Hz and 12 Hz wide at 360 Hz. Because the width grows with frequency, each harmonic gets the same proportional notch, which also helps when the hum drifts slightly. Strength places one, two or three identical notches on each harmonic; stacking them makes each notch deeper and a little wider.
The estimated reduction compares the energy in the narrow bands around each harmonic before and after filtering, using the measured spectrum of your file.
Tips for a cleaner result
Prevent hum at the source when you can: use balanced XLR or TRS cables, plug all gear into the same outlet strip and keep audio cables away from power cords.
Listen to Removed hum only. You should hear a steady buzz and very little speech; if words come through clearly, raise Q.
Remove hum first, then apply EQ, compression or noise reduction, because compression makes hum louder in quiet gaps.
For hum plus low rumble, add a gentle high-pass filter at 60-80 Hz afterwards.
Frequently asked questions
What causes 50 Hz or 60 Hz hum?
Hum is the frequency of the mains electricity leaking into the audio: 60 Hz in North America and parts of South America and Asia, 50 Hz in most of Europe, Asia, Africa and Australia. Common causes are ground loops between devices, unbalanced cables running near power cords, dimmer switches, fluorescent lights and faulty power supplies.
Why remove the harmonics and not just 50 or 60 Hz?
Real hum is rarely a pure tone. It usually contains whole-number multiples of the mains frequency (120, 180, 240 Hz and so on for 60 Hz hum) that make it sound like a buzz. Removing only the fundamental leaves the buzz, so the tool places a notch on each harmonic.
Will removing hum affect the voice or music?
Each notch removes only a narrow band around one frequency, so most of the sound is untouched. With a high Q the notches are very narrow and hard to hear; with a lower Q or Strong setting they remove more hum but can thin out low voices or bass notes that sit on the same frequencies. Use Removed hum only to check that you are not removing wanted sound.
How does the automatic detection work?
The tool averages a high-resolution spectrum (up to 32,768-point FFTs) across the recording and checks the peaks at multiples of 50 Hz and 60 Hz against the sound around them. The set with the stronger, more consistent peaks wins, and the exact frequency is measured from the peak positions.
What Q and strength should I use?
Start with Q 30 and Standard strength. If hum remains, lower Q to 15 to 20 or choose Strong. If the result sounds thin or hollow, raise Q to 50 or more. If the hum drifts in pitch, as with some generators, a lower Q handles the drift better.
Can it remove other noise, like hiss or fan noise?
No. Notch filters only remove hum at fixed frequencies. For broadband noise such as hiss, air conditioning or fans, use a noise reducer; for rumble, use a high-pass filter.
Is my audio uploaded?
No. Decoding, analysis, filtering and encoding all happen in your browser with the Web Audio API. Only the MP3 encoder script is downloaded once if you choose MP3.
Are all the tools on FreeToolCabin tested for quality and accuracy?
Yes! Every tool on our site undergoes automated Q/A testing in real browser environments to ensure high precision, correct output, and zero errors. If you happen to spot a bug or have a suggestion, please contact us at [email protected] and our team will review it right away.