How to Remove Background Noise in Audacity (Step by Step)

Audacity's Noise Reduction effect removes steady background noise — fan, AC, hum, hiss — for free, entirely offline. The trick that trips people up is that it's a two-pass tool: first you show Audacity what the noise sounds like, then you tell it to remove that from the whole recording. Here's the plain-English version.

Audacity's two-pass noise reduction

Step by step

Open your file in Audacity. File ▸ Open (or drag it in). Audacity is a free download for Mac, Windows and Linux.
Select a noise-only region. Find a 1–2 second stretch with no speech — just the hum or hiss — and click-drag to select it. This is the sample Audacity will learn from, so pick a clean patch.
Get the noise profile. Go to Effect ▸ Noise Reduction… and click Get Noise Profile. The window closes — that's expected. You've just taught Audacity what the noise sounds like.
Select the whole track. Press ⌘A (Mac) or Ctrl+A to select everything.
Open Noise Reduction again and tune it. Back in Effect ▸ Noise Reduction…, three sliders: Noise reduction (dB) — how much to remove; Sensitivity — how aggressively it decides what's noise; Frequency smoothing — softens artifacts. Start gentle (around 12 dB, sensitivity 6, smoothing 3), click Preview, adjust, then Apply.
Export. File ▸ Export Audio and choose WAV or MP3.

Don't over-reduce

Pushing the reduction too high makes voices sound thin, watery or "underwater." If you hear that, lower the dB and raise frequency smoothing. A little residual hum usually sounds more natural than an over-processed voice — the same rule applies in any denoiser.

Common problems

"It barely did anything." Your noise sample probably had speech in it, or the reduction was too low. Re-select a cleaner noise-only patch and try a few dB more.
"It sounds robotic now." Too aggressive — lower Noise reduction and Sensitivity, raise Frequency smoothing.
"Background voices are still there." Expected. Noise Reduction handles steady noise; other people's voices and echo aren't steady, so they mostly remain — see what noise can (and can't) be removed.
"I have to redo this for every file." Also expected — the profile is per-recording. That repetition is the main downside of the manual approach.

The faster alternative

Audacity is great when you want free and don't mind the steps. If you'd rather skip the noise-profile dance — or you need to clean a video, batch a folder, or get consistent loudness — Soundproof does the whole thing in one drop on your Mac: no profile to draw, no sliders to guess, and it LUFS-normalizes the result. It's a one-time purchase with a free download so you can compare on your own file.

Or skip the steps entirely

Soundproof removes steady background noise and levels loudness in a single drop — audio or video, on your Mac, no noise profile required. Download it free and try it on the same file.

Download Soundproof Soundproof vs Audacity →

macOS 13.4+ · Apple Silicon & Intel · Works offline · One-time purchase, no subscription

Frequently asked questions

Is Audacity free?

Yes — Audacity is free, open-source, and runs offline on Mac, Windows and Linux. The Noise Reduction effect is built in.

Why do I select noise first?

Audacity's Noise Reduction is a two-pass effect. The first pass ("Get Noise Profile") learns what the noise sounds like from a sample; the second pass removes that profile from the whole track.

What settings should I use?

Start gentle — around 12 dB reduction, sensitivity 6, frequency smoothing 3 — then Preview and adjust. Lower the dB if voices start sounding watery.

Can Audacity remove background voices or echo?

Not reliably. Noise Reduction targets steady noise like hum and hiss. Background voices and echo aren't steady, so they usually remain.

Is there a one-click alternative?

Yes. Soundproof removes steady noise and levels loudness in a single drop on your Mac, cleans video too, and needs no noise profile — a one-time purchase versus Audacity's free-but-manual workflow.