Noise reduction and noise gate

Capture a noise profile

1. Select a passage containing only the noise you want to remove, ideally a second or more with no speech or music.
2. Open Process → Noise Reduction… and click Get Noise Profile.
3. Select the audio to clean and reopen the effect. Set the reduction in dB, the sensitivity, and the frequency smoothing.
4. Preview the reduced audio, then switch Output to the residue to hear what would be removed. Switch back to reduced audio before applying, unless you deliberately want to keep only the noise.

A profile describes steady noise such as hiss, fan rumble, or hum. If recognisable speech appears in the residue, use gentler settings. The profile lasts for the current editor session and must match the source sample rate, so capture it again after a reload or for audio at a different rate.

Lower noise between phrases

Process → Noise Gate… turns down audio below a threshold. Attack, hold, and release shape how the gate opens and closes, and level reduction sets how quiet a closed gate becomes, down to digital silence at −100 dB. Select a noise-only passage and click Analyze noise level for a suggested threshold 6 dB above the measured noise.

The gate offers linked or independent channels and an optional Gate above frequency that leaves the low end untouched. It preserves duration and suits gaps between phrases. It cannot separate a voice from noise that occurs at the same time.

Keep quiet speech intact

Preview quiet syllables and word endings before treating a whole recording. Both effects support cancellation, undo, and Repeat Last Effect; repeating Noise Reduction reuses the current session profile with the last applied settings.

For low rumble use a high-pass filter, and for a narrow hum use Plot Spectrum to find it and a notch filter to remove it. To shorten the pauses themselves rather than clean them, use Truncate Silence.