How to Reduce Background Noise in OBS (Noise Suppression)

There are two different noise problems, and OBS has a different tool for each. Constant noise, the fan hum or air conditioner that runs under everything you say, is a job for Noise Suppression. Intermittent noise in the gaps between sentences, keyboard clatter or a room that will not be quiet, is a job for a Noise Gate.

Reach for the wrong one and you get the two classic failures: a voice that sounds like it is underwater, or first syllables that keep getting chopped off. This page covers both filters, the method you should pick, the numbers to start from, and the point at which no filter will save you.

Adding the Filters

Both live in the same place. In the Audio Mixer dock, click the gear icon or the three dots next to your microphone and choose Filters. Click + at the bottom left to add one.

If your microphone is not in the mixer at all, or its meter is not moving, the problem is upstream of filters. Start with setting up a microphone in OBS and come back once the meter is bouncing at a sane level.

Noise Suppression: Pick the Right Method

Add Noise Suppression and you get a Method dropdown. The choice matters more than any other setting on this page.

RNNoise is what most people should use. It has no settings to get wrong, it is genuinely good at fan noise and keyboard clicks, and it leaves the voice alone.

Speex exists for weak machines. Its slider defaults to -30 dB, which is reasonable. Pushing it to -60 dB is where the underwater artefacts come from, so if you need that much suppression, the fix is the room or the microphone, not the slider.

NVIDIA Noise Removal only appears if you have an RTX card with the NVIDIA Broadcast SDK installed. It is the most aggressive option available and it moves the work to the GPU, which is worth knowing if the GPU is already busy encoding. It can also thin out the voice slightly at high intensity, so back it off from 100% if you sound processed.

Suppression runs on the whole signal continuously. It removes what is steady and predictable. It cannot remove a door slamming.

Noise Gate: Silence Between Sentences

A gate mutes the microphone when the input falls below a threshold, so the gaps in your speech become true silence instead of room tone.

Add Noise Gate after the suppression filter. The two thresholds are the whole feature:

• Close Threshold: the level below which the microphone mutes.
• Open Threshold: the level at which it unmutes.

Do not guess these numbers, measure them. Sit in your normal recording position, stay silent, and read where your microphone's meter rests: that is your room floor. Then speak normally and read your peaks.

• Set Close Threshold about 5 dB above the room floor.
• Set Open Threshold about 5 to 10 dB above the close threshold, and comfortably below your speaking level.
• A common starting pair is -50 dB close, -40 dB open, but a noisy room or a distant microphone will need both raised.

The gap between the two values is deliberate. A single threshold makes the gate stutter open and shut on every breath. This is called hysteresis and it is the reason the two numbers exist.

Two more settings prevent the chopped word problem:

• Attack Time around 25 ms. Too slow and the start of each word is quiet.
• Release Time around 150 ms, with Hold Time around 200 ms. Too fast and the ends of your words get clipped, which is what makes gated speech sound clipped and robotic.

If you are still losing first syllables, lower the open threshold before touching anything else.

Filter Order, and Why It Is Not Arbitrary

OBS processes filters top to bottom, and each one only sees what the previous one produced. This chain works:

1. Noise Suppression
2. Noise Gate
3. Compressor
4. Limiter

Suppression goes first so the gate is measuring a cleaner signal. Put the gate first and it has to decide open or closed based on speech plus noise, so it either opens on the fan or clamps down on you.

The compressor goes after the gate for the same reason in reverse. A compressor raises quiet material toward the loud material, so any noise still present gets raised too. Running it after the gate means it only ever works on speech. Compressor starting points: ratio 4:1, threshold -18 dB, attack 6 ms, release 60 ms, output gain to taste.

A Limiter at -3 dB last is cheap insurance against a sudden loud moment clipping the file.

Drag filters into order with the arrows at the bottom of the filter list. The order in that list is the signal chain.

What Filters Cannot Fix

Worth being blunt about, because this is where people stack five filters and make things worse.

• Room echo. Reverb is your own voice arriving late off hard surfaces. Suppression does not touch it because it is not steady, and a gate does not touch it because it happens while you are talking. The fixes are physical: get closer to the microphone, and put something soft on the wall behind you.
• A microphone that is too far away. Distance is the single biggest driver of noise in most setups. Every doubling of distance drops your voice relative to the room. A microphone 15 cm from your mouth needs almost no processing. One across the desk needs a lot, and will still sound worse.
• Gain set too high to compensate. Turning up a distant microphone turns up the room. Move closer and turn the gain down.
• Fan noise from your own machine. If the computer is under the desk pointing at the microphone, no filter beats moving one of them.
• Clipping. Already distorted before any filter runs. Nothing recovers it. OBS mic crackling and distorted audio covers the causes.

Filters buy you maybe one grade of improvement. Microphone position buys three.

The CPU Cost

Audio filters are cheap next to video encoding, but they are not free, and they are on the same critical path.

RNNoise on a single microphone is negligible on any current machine. RNNoise on six sources, on an older CPU, while encoding with x264, is not. If frames start dropping after you add filters, check View → Docks → Stats to see whether the problem is rendering or encoding, then read OBS encoding overloaded. On a marginal machine, Speex costs almost nothing, and NVIDIA Noise Removal moves the work off the CPU entirely if the GPU has headroom.

Also apply filters to the microphone source, not to a scene or to everything. Filtering desktop audio with a speech model produces exactly the strange results you would expect.

When You Just Want It to Sound Right

This chain is worth building once if you stream, or if you record often enough that the setup amortises. It is a genuinely powerful audio system and the numbers above will get you most of the way.

It is also five filters, a dozen parameters, and a measurement session with a dB meter, in service of narrating a five minute product walkthrough. Cubix Capture takes the other route: it captures your microphone and system audio together with no filter chain to build, and spends its complexity on the video instead, framing and zooming toward wherever you are working so the recording is finished when you stop. It runs on Windows and macOS with a free Starter plan.

If your recording is a live broadcast with guests, music and alerts, build the chain. It is the right tool and nothing else gives you that control.

Keep Reading

• How to Set Up a Microphone in OBS for device selection, levels and track routing before filters.
• How to Record Screen Without Background Noise for the recording environment side, tool independent.
• How to Fix Audio Echo in OBS Recording for the doubled voice that no gate will remove.
• OBS Mic Crackling and Distorted Audio for distortion that arrives before any filter.
• OBS High CPU Usage if the filter chain is what pushed you over the edge.