To remove background noise from a recording, first cut low rumble with a Low Cut filter at 80 to 100 Hz, then use a noise gate set a few decibels above the noise floor so the pauses between your words go silent. A gate cannot remove noise that sounds while you are speaking, so a quiet room and a microphone close to your mouth still matter most.
In Short
The short version:
- Record close to the microphone in the quietest room you have.
- Cut rumble below 80–100 Hz with a Low Cut filter.
- Set the noise gate threshold just above the level of the room noise.
- Lengthen the release if the ends of your words get cut off.
- Accept a little noise under your voice: a gate only cleans the pauses.
What Kind of Noise Are You Dealing With?
“Background noise” covers several different problems, and each one needs a different fix. Listen to a pause in your recording on headphones and work out which of these you hear.
| Type of noise | What it sounds like | What helps |
|---|---|---|
| Rumble | Low thumps from traffic, footsteps or bumps on the desk | A Low Cut (high-pass) filter at 80–100 Hz |
| Hum | A steady low tone from household power, a fridge or an air conditioner | Low Cut for the lowest part, a noise gate for the pauses |
| Hiss | A soft “shhh” from the microphone, the preamp or a high gain setting | A noise gate for the pauses; a gentle High Cut if it is very bright |
| Room echo | A hollow, distant sound, as if recorded in a bathroom | Soft furnishings and a closer microphone; it can’t be gated out |
| Sudden sounds | A door, a dog, a keyboard or a notification | Cut them out by hand, or record the sentence again |
Step 1: Reduce the Noise Before You Record
Every tool in this guide works better when the voice is much louder than the noise behind it. Engineers call this the signal-to-noise ratio, and you can improve it for free before you press record:
- Get closer. Speak 10 to 15 cm from the microphone. Your voice gets louder at the microphone while the room noise stays the same.
- Turn down the input gain. Once you are closer, you need less gain, and less gain means less hiss and less room noise.
- Switch off what you can. Fans, air conditioning, the fridge next door and notification sounds are easier to remove at the source than in software.
- Soften the room. Curtains, a rug, a sofa or a wardrobe full of clothes absorb reflections and reduce echo.
- Record ten seconds of silence. This “room tone” shows you how loud your noise floor is and makes setting a gate much easier.
Why this works: bare walls and hard surfaces reflect your voice back into the microphone a moment later, and soft materials absorb those reflections. The physics is covered in the University of Illinois lecture notes on room acoustics .
What Is a Noise Gate and How Does It Work?
A noise gate is an automatic volume control. While the signal is louder than a level you choose, the gate stays open and the sound passes through untouched. When the signal falls below that level, the gate closes and turns the sound down or mutes it. A gate does not recognize voices: it only reacts to level, which is why it silences the pauses but leaves the noise under your words alone.
- Threshold: the level at which the gate opens. Set it just above the room noise and below your quietest words.
- Attack: how fast the gate opens. For speech it should be fast, a few milliseconds, so the first consonant isn’t lost.
- Release: how slowly the gate closes after the sound drops below the threshold. Longer release times (150 to 300 ms) let word endings and breaths fade out naturally.
- Range (or reduction): how much the gate turns the sound down when it is closed. Full muting is the most obvious; reducing the noise by 10 to 20 dB often sounds more natural.
A gate that reduces the level gradually instead of muting it is called a downward expander. Many “noise gate” tools work this way, because a little remaining room tone sounds less abrupt than complete silence.
How to Remove Background Noise Online, Step by Step
You can do the whole clean-up in your browser. The steps below use the Sound Optimizer, which has a Low Cut filter and a noise gate on one page; if you only need a gate and a de-esser, the Noise Gate & De-Esser works the same way.
Step 1: Open Your Recording
Open the tool and choose your file. It is processed in your browser, so the recording is not uploaded anywhere. Put on headphones: small amounts of noise are hard to judge on laptop speakers.
Step 2: Cut the Rumble
Press Play and raise Low Cut to between 80 and 100 Hz. Rumble and most of a low hum disappear, and a speaking voice loses nothing important. For deep voices, stay nearer 80 Hz.
Step 3: Find the Noise Floor
Play a pause where nobody is speaking and listen to what is left. This is the noise the gate has to remove. If you recorded ten seconds of room tone, use that.
Step 4: Set the Noise Gate
Raise the Noise Gate threshold slowly until the pause goes silent, then play a full sentence. If quiet syllables or word endings disappear, lower the threshold by a few decibels. In the Sound Optimizer, most voice recordings end up between -60 and -45 dB.
Step 5: Smooth the Edges
If the gate sounds choppy, give it more time to close. In the Noise Gate & De-Esser you can lengthen the gate release; start around 150 to 250 ms for speech. If a click remains at one spot, a short fade with the Audio Fade Tool hides it.
Step 6: Check and Download
Listen to the whole recording once, especially the quiet passages, then download the WAV file. If hiss is still audible under your voice, leave it: removing it would damage the voice more than the hiss does.
Noise Gate Settings: Good Starting Points
The right threshold depends on your room and your microphone, so treat these values as starting points and adjust by ear.
| Situation | Threshold | Release | Tip |
|---|---|---|---|
| Voice-over in a quiet room | 5–6 dB above the noise floor | 150–250 ms | A light setting is enough; don’t chase total silence |
| Laptop fan or air conditioning | Just above the fan noise | 200–300 ms | Use Low Cut first, so the gate has less to do |
| Keyboard and mouse clicks while streaming | Just below your quietest speech | 100–150 ms | Clicks louder than your voice will still open the gate |
| Singing or instruments with long notes | As low as possible | 300–500 ms | Long tails are easily cut off; often no gate is better |
What a Noise Gate Cannot Remove
Knowing the limits saves a lot of frustration. A gate is the right tool for pauses and the wrong tool for these three problems:
- Noise under your voice. While you speak, the gate is open and the noise passes through with the words. If the noise is quiet compared with your voice, listeners rarely notice it.
- Echo and reverb. Room reflections are part of the voice signal itself. Only a softer room or a closer microphone fixes them.
- Loud, sudden sounds. A barking dog or a slammed door is louder than the threshold, so it opens the gate. Cut the moment out with the Audio Trimmer or record the sentence again.
Desktop audio editors offer spectral noise-reduction tools that can lower steady noise under speech. They can help, but at strong settings they leave a watery, robotic sound. The free tools on this site don’t include that kind of processing; they keep to filters and gating, which leave the voice itself untouched.
Common Mistakes to Avoid
- Setting the threshold too high. The pauses are silent, but so are soft consonants and word endings. Always check a full sentence, not just a pause.
- Gating after compression. A compressor raises quiet sounds, including the noise. Gate first, then compress. In the Sound Optimizer the gate already comes first in the chain.
- Boosting treble on a noisy recording. A bright EQ makes hiss louder. Clean up first and add only a small boost afterwards.
- Expecting silence between every word. Abrupt silence sounds unnatural. A little steady room tone is easier on the ear.
- Fixing in software what a closed window would fix. Two minutes spent on the room save more than twenty in editing.
What to Do After the Noise Is Gone
- Make the voice itself clearer with EQ and a de-esser: How to Make Your Voice Sound Professional.
- Adding music under your voice? Read How to Mix Vocals and Background Music.
- For level, compression and export settings, see How to Use the Sound Optimizer Tool.
Clean Up Your Recording Now
Open your file, raise the gate until the pauses go quiet and listen to the difference.
Open the Noise Gate & De-EsserFree, no sign-up, and your files never leave your device.