How does the tool know what the noise sounds like?

It measures it instead of asking. The quietest stretch of the recording is assumed to be the noise floor, and its spectrum becomes the profile that everything else is compared against. That works well whenever the take has a genuine pause in it, and it is the reason the tool asks for material with a moment of just the noise.

What does mean gain reduction mean in the report?

It is the average amount of level the subtraction removed across the file, in decibels. A larger number means the process worked harder, not that the result is better; heavy settings raise it while also raising the chance of watery artifacts, so compare by ear rather than chasing the figure.

Why does my recording sound hollow after reducing noise?

That is over-subtraction. The profile is subtracted from every window, so bands where signal and noise overlap lose energy along with the noise, and pushing the strength past about 70 percent makes the effect obvious. Lower the strength, or accept a little remaining noise in exchange for natural tone.

Can it remove traffic or a crowd?

No, not reliably. The method assumes the noise is steady enough that one profile describes it throughout, and traffic, crowds and wind gusts all change over time. For moving or intermittent noise the targeted repair tools, or a re-record with a tighter microphone position, will get you further.

Is the original file changed?

No. The decoded audio is held in the browser, processed in memory and written out as a new WAV under a denoised suffix. Your original file is untouched and nothing is uploaded at any point, so a pass you dislike costs nothing but the time to run it again.

Noise Reducer

You Might Also Need

Background Noise Remover

Remove constant background hum

Hiss Remover

Eliminate tape hiss and high-frequency noise

Hum Remover

Remove electrical hum and buzz

Audio Gate

Noise gate to silence quiet parts

Noise Reducer strips steady broadband noise from a whole recording by measuring the noise from the quietest stretch of the file itself. No sample has to be marked by hand, and nothing is uploaded.

What is Noise Reducer?

Load a file, choose a strength and the tool cleans the entire recording in one pass. The noise profile is taken automatically from the calmest part of the audio, so the tool wants material that contains a genuine stretch of the noise floor alone, such as a pause or a room tone at the head of a take. That single estimate is what every other part of the file is judged against.

What you control and what you get back:

A strength slider from 0 to 100 percent in steps of 5, defaulting to 50.
An automatically measured noise profile, taken from the quietest stretch of the recording.
A report line listing the strength used, the mean gain reduction in dB and the number of channels written out.
A WAV download named after the source file with a denoised suffix added.
Plain language errors, so an undecodable file or a failed pass says so rather than failing silently.

The engine is spectral subtraction with overlap-add resynthesis. The signal is analysed in short windows, the noise magnitude spectrum is estimated from that quietest stretch, a strength-scaled copy of it is subtracted from every window's spectrum and the result is put back together with the overlap-add method so the window seams never become audible. The mean gain reduction in the report is how much level the process removed on average, and it is worth reading as an amount of work done rather than a score: a bigger number can simply mean a heavier hand. Strength scales the subtraction, with 0 leaving the file untouched and the top of the range trading a lot of noise for the hollow, watery artifact that over-subtraction is known for.

Where it stops being the right tool:

The profile comes from one quiet stretch, so a recording with no pause of pure noise gives it nothing reliable to estimate from.
Noise that changes as it goes, such as traffic, crowd murmur or a passing fan, is not steady enough for a single profile to describe.
High strengths introduce a swirling artifact that is frequently more distracting than the noise they removed; 40 to 70 percent is usually the sweet spot.
Anything sharing the noise spectrum is reduced alongside it, so breaths, room tails and air around a voice can lose body.
It is not a separator: a conversation recorded in a busy room comes back cleaner but not clean, because speech and noise overlap in the same bands.
The pass writes a fresh WAV, so there is no live preview and no undo inside the tool.

Use it when the noise is constant and the signal of interest sits somewhere else in the spectrum, which is the case for most hiss, hum-laced room tone, preamp noise and steady tape noise. Start around the halfway point and compare a few strengths on the same passage by ear rather than trusting the reduction figure, because the measured gain reduction says nothing about how natural the result sounds.

How to use Noise Reducer

Choose an audio file that contains a short passage of noise alone, such as a pause before the first word.
Set the strength slider, starting around 40 to 70 percent for most material.
Click Reduce noise and wait for the pass to finish; the report shows the strength, mean gain reduction and channel count.
Download the file and compare it with the original before deciding whether to run a second pass at a different strength.

When to use Noise Reducer vs related tools

Noise Reducer handles broadband, steady noise that spans the spectrum, which is a different job from the targeted tools beside it. Background Noise Remover notches out electrical hum and its harmonics instead, Hiss Remover rolls off tape and preamp hiss above a chosen corner, and Hum Remover does the same narrow work with mains-oriented defaults. When the problem is speech dropping into gaps rather than noise riding on top of it, Audio Gate mutes the quiet parts outright.

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.