Which fundamental should I pick, 50 Hz or 60 Hz?

It depends on where the recording was made. Europe and most of the world run mains at 50 Hz, North America and parts of Asia at 60 Hz, and the buzz you hear is that frequency plus its multiples. The 100 Hz button is for mechanical whine and motor noise that sits above the mains rather than at it.

What does the harmonics control actually change?

A real hum is never a single tone; it is the fundamental plus a stack of multiples created by the equipment producing it. Each harmonic you add places one more notch at a multiple of the fundamental. Eight is a sensible default because the upper harmonics are usually weak, so chasing them all costs filtering for very little removal.

Why would I lower the Q value?

Because a lower Q widens each notch. Mains frequency wanders slightly with grid load, and equipment sometimes shifts the hum as it warms, so a wide notch keeps catching it. The trade is that a wide notch removes more legitimate energy around every harmonic, so keep Q high when the tone is rock steady.

Will this remove hiss or air conditioning noise?

No. The tool removes energy at exact multiples of one frequency, and hiss or air noise is spread across the whole spectrum rather than concentrated at a pitch. For that kind of constant broadband backdrop you want the spectral approach in Noise Reducer, which estimates and subtracts a noise profile instead.

How do I know which frequency the hum is at?

The tool does not measure it, so you judge it by ear or from the context of the recording. Mains-derived buzz almost always sits at 50 or 60 Hz, motor and fan whine on top of that is usually an octave up, and if the three buttons do not fix it, the noise is probably not a harmonic comb at all and a different tool fits better.

Background Noise Remover

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Background Noise Remover takes out the steady electrical or mechanical backdrop that sits under a recording, by notching its fundamental and every harmonic of it. It is built for the broadband constant drone — transformer hum, fridge whine, mains buzz — rather than for hiss or clicks.

What is Background Noise Remover?

Pick the fundamental, decide how many harmonics to chase and set how wide each notch should be, then run the file through the chain. Because the fundamental and its multiples are removed as a family, a 50 Hz buzz takes its 100, 150 and 200 Hz companions with it, which is what makes the drone disappear rather than half-disappear.

The controls, with their real ranges:

A fundamental of 50 Hz, 60 Hz or 100 Hz, presented as three buttons and defaulting to 60.
A harmonic count from 1 to 16, defaulting to 8, with the chain stopping before it reaches the top of the spectrum.
A notch width expressed as Q from 8 to 40 in steps of 2, defaulting to 20.
A report line naming the fundamental, the number of harmonics actually applied and the Q used.
A WAV download named after the source with a cleaned suffix.

Each harmonic is a second order notch filter built from the standard RBJ biquad formulas and applied in series, one filter per harmonic per channel, which makes the chain a bank of narrow notches rather than one broad cut. The chain stops as soon as a harmonic would land within a hundred hertz of the Nyquist limit, so no attempt is made to build a filter that cannot exist at the rate you are running. Wider notches, meaning a lower Q, catch a hum that wanders with load while taking some legitimate tone with it, and narrower notches leave more of the music intact but need the source frequency to be stable. This is deliberately the broader variant of the idea: more harmonics and a slightly wider notch than the mains-focused Hum Remover, which is why it reports what it removed.

What it cannot do:

It only removes energy at exact multiples of one frequency, so broadband noise such as air conditioning or hiss passes straight through.
If the true mains frequency is not on one of the three offered buttons, every notch lands in the wrong place and the drone survives untouched.
A hum that drifts with load needs a wider notch, which costs tone around every removed band.
Removing many harmonics at wide Q can hollow out the low end of a bass-heavy recording.
It is a fixed chain rather than an adaptive canceller, so it cannot track a changing buzz in real time.
There is no measurement step: the tool does not tell you which frequency the noise is actually at, so you are choosing from experience.

Reach for it when you can hear a steady pitch under everything and you know roughly where it lives: 50 Hz for European mains, 60 Hz for North American, and 100 Hz for the mechanical whine of fans and motors that sit an octave above the mains. If the source frequency is unknown, guess from where the recording originated, because a comb aimed at the wrong fundamental removes nothing while still thinning the spectrum around each misplaced notch. Start with the default harmonic count, listen, and reduce Q only if the hum is still moving after the pass.

How to use Background Noise Remover

Load the recording and choose the fundamental that matches the noise, starting with 50 or 60 Hz for mains hum.
Set how many harmonics to remove; the default of 8 covers a typical buzz up past the midrange.
Set the notch width with the Q control, using a lower value if the hum wanders in pitch.
Click Remove background noise, read the report to see which harmonics were applied, then download the cleaned WAV.

When to use Background Noise Remover vs related tools

Background Noise Remover is the broad hum tool, so choose it when the drone is clearly a family of tones and you want the whole comb gone. Hum Remover does the same job with mains-oriented defaults and a sharper notch, which suits a steady 50 or 60 Hz buzz you do not want to disturb anything else for. When the noise is not tonal at all, Noise Reducer works on broadband noise instead, and when the low end is being stolen by rumble rather than a fixed pitch, Wind Noise Remover is the cleaner answer.

Privacy & Security

This tool runs entirely in your browser — no data ever leaves your device. There is no server round-trip, no upload, no logging, and no account required. Your input is processed locally using client-side JavaScript and is never stored, transmitted, or accessible to anyone else. When you close the tab, everything disappears.