How to remove background noise in Audacity

Audacity has offered free noise reduction for years, and it still works well once you know the sequence of steps. The catch is that it's not a one-click fix. You have to manually sample the noise before Audacity can remove it. Here's the accurate, current workflow, plus a faster route if you'd rather skip the setup.

The fast way (online, free)

If you don't want to hunt for a noise-only section, learn what dB, Sensitivity and Frequency Smoothing actually do, or install Audacity at all, CleanNoise's online noise remover does the equivalent job automatically:

1. Open CleanNoise in your browser and drop in your audio file.
2. CleanNoise scans the whole recording and detects the steady background noise itself, so there's no separate noise-sample step to select or get wrong.
3. It cleans the noise in one click, with no settings to tune and no noise-sample step.
4. Preview the before/after, then download the cleaned file.

There's no export/import round trip through a desktop editor either, which helps for a quick podcast edit or a voice memo you need cleaned in the next five minutes. Working from a video file instead of an audio file? Use the extract audio from video tool first, or clean the video's audio track directly with the video noise remover.

Audacity's own method: Noise Reduction

Audacity is free and open-source, and its Noise Reduction effect is genuinely effective, but it has a real learning curve because it works in two passes: first you teach it what the noise sounds like, then you apply the reduction.

1. Open your recording in Audacity and find a stretch of a few seconds where there's only background noise. A pause before anyone speaks works well.
2. Click and drag to select just that region on the waveform.
3. Go to Effect > Noise Removal and Repair > Noise Reduction and click Get Noise Profile. The dialog closes immediately; this step only captures the profile, and doesn't change your audio yet.
4. Select the entire track with Ctrl+A (Windows/Linux) or Cmd+A (Mac).
5. Reopen Effect > Noise Removal and Repair > Noise Reduction. This time you'll see three sliders: Noise Reduction (dB), Sensitivity, and Frequency Smoothing (bands).
6. Click Preview to hear the result before committing. Adjust the sliders and preview again until the noise is gone but voices don't sound underwater or warbly.
7. Click OK to apply the effect to the whole selection, then File > Export to save your cleaned file (WAV or MP3).

Tips for better results in Audacity

• Pick the quietest, cleanest noise-only region you can find; a noisy or short sample makes for a worse profile.
• Start with a moderate dB reduction (around 12) rather than maxing it out; you can always reapply for more.
• High Sensitivity settings remove more noise but risk chewing into quiet parts of speech, so lower it if voices start cutting in and out.
• Always use Preview before clicking OK, because Noise Reduction can't be tuned after the fact without undoing and starting over.

Which method should you use?

Audacity is the right call when you want full manual control, you're comfortable tuning three interacting sliders, or you're already doing other editing in the app anyway. It costs nothing and the results can be excellent. If you just want a clean file quickly, don't want to hunt for a noise sample, or find the two-pass workflow more fiddly than your task deserves, CleanNoise gets you the same kind of result in one step. Check pricing if you need to process longer files or batches regularly.