Remove Background Noise from Audio

About Remove Background Noise from Audio

Drop in a recording and get it back without the steady background noise — the hiss of a cheap microphone, the hum of the mains, a fan, an air conditioner, traffic through a window.

You get two players, before and after, so you can hear exactly what changed before you decide to keep it.

It is free, needs no account, and the recording is never uploaded. Everything happens inside your browser.

How it works

The method is called spectral subtraction, and the idea is simpler than the name.

Steady noise has a fixed shape. A fan is mostly low rumble. Hiss is mostly high. Mains hum sits at exactly 50 or 60 Hz. Speech, by contrast, moves constantly — it jumps around in pitch and loudness with every syllable.

So if you can measure that shape once, you can subtract it from every moment of the recording, and what is left is the part that moves.

Finding the noise is the clever part. Rather than ask you to select a silent patch — which is fiddly and easy to get wrong — the tool looks at the whole recording, finds the quietest tenth of it, and averages that. Almost every real recording has a gap before someone starts talking, and what is in those gaps is the noise by definition.

Why it does not sound like a broken radio

If you subtract the noise all the way to zero, a few isolated frequencies survive here and there in what should be silence. The ear hears them as random tinkling — a fault so well known that engineers have a name for it, "musical noise", and it is far more annoying than the hiss ever was.

The fix is to never go all the way down. The Keep this much of the original control leaves a small fraction of every frequency in place, which masks those stray survivors. Turning it up gives a more natural but slightly noisier result; turning it down is cleaner but risks the tinkling.

The honest limits

• It removes steady noise only. A door slam, a cough, a chair scrape or a second person talking cannot be removed, because they change from moment to moment exactly like the voice does. Nothing that works this way can separate them.
• Pushed hard, it thins the voice. Speech and hiss share the high frequencies, so removing all the hiss takes some of the voice with it. That is why the strength control exists and why you can hear the result first.
• It cannot rescue a hopeless recording. If the noise is louder than the voice, there is not enough voice left underneath to recover.
• A quiet room beats any tool. This is a repair, not a substitute for recording well.

What you can do with it

• Clean up a voice memo or an interview recorded in a noisy room
• Improve a video's sound — pull the audio out first with Video to Audio
• Remove the mains hum from a guitar or keyboard recording
• Tidy a lecture or a meeting recording before sharing it
• Clean speech before transcribing it — a cleaner recording gives better results in Audio to Text
• Take the hiss off an old cassette or vinyl transfer

Features

• Finds the noise by itself — no need to select a silent part
• Before and after players, so you judge with your ears
• Strength control for how much to remove
• A floor control that prevents the tinkling artefacts cheap tools leave behind
• Mains hum removal for 50 Hz and 60 Hz and their harmonics
• Optional gate to make the gaps between words properly quiet
• Keeps stereo and matches the original loudness
• MP3, WAV, M4A, FLAC, OGG in; full-quality WAV out
• 100% in your browser — nothing uploaded, no sign-up

Good to know

• Start in the middle and listen. The best setting depends entirely on the recording; there is no single right answer.
• A little remaining hiss sounds better than a damaged voice. Listeners forgive background noise far more readily than a thin, underwater voice.
• The download is a WAV, which keeps full quality but is large. Use the Audio Converter to make an MP3.
• A long recording uses a lot of memory. On a phone, work in chunks with Trim Audio.

Related tools

• Vocal Remover — take the singer out of a song instead
• Audio Converter — turn the WAV into an MP3
• Trim Audio — cut the recording down first
• Video to Audio — pull the sound out of a video
• Audio to Text — transcribe the cleaned recording

How to use it

• Drop a recording in — MP3, WAV or M4A
• Press Clean up the sound and wait a moment
• Listen to both players — before, then after
• Too much voice lost? Turn How much to take out down and run it again
• Hear a faint tinkling? Turn Keep this much of the original up
• Buzzing from mains power? Tick Remove mains hum
• Press Download the WAV to save it