Audio Denoise reduces the fairly steady background noise in a recording — fan noise, electrical hum, air-conditioning rumble. The panel offers three afftdn frequency-domain strengths, Light, Medium and Strong, and starts on Medium with “Also filter low-frequency hum below 80Hz” switched on by default.

This implementation is not AI speech enhancement and does not learn from a noise sample; it runs ffmpeg's FFT denoising filter over the whole recording. The stronger the setting, the more likely it is to shave off detail in the voice as well, and the interface states plainly that the Strong tier can leave audio sounding muffled.

1. 01Select the audio— pick the recording in the left-hand side of the workbench and open the “Audio denoise” tab.
2. 02Choose a strength— try Medium first; move to Light when the noise floor is low, or try Strong when the noise is clearly audible.
3. 03Decide on the high-pass— an 80 Hz high-pass is on by default and suits mains hum and low-frequency air-conditioning noise; consider turning it off for material with low-frequency instruments.
4. 04Start denoising— check the ffmpeg command, click “Start denoising”, then listen to and download the result when the job finishes.

Noise it suits

— afftdn works better on continuous, fairly steady fan noise, electrical hum and hiss; sudden knocks or a second person talking are not removed reliably.

Three strengths

— Strong changes the spectrum more obviously and can leave voices muffled or watery; there is no automatic preview and no automatic pick of the best tier.

80 Hz high-pass

— once enabled it genuinely deletes everything below 80 Hz, not just noise; be careful with music, low male voices and low-frequency effects.

Output format

— re-encoded keeping the source extension where possible, and formats the current engine cannot encode, such as WMA/AMR, fall back to MP3.

What it does not do

— no AI voice separation, echo removal or per-section noise learning; use Silence Removal for silent gaps.

The recording is processed locally in the browser by ffmpeg.wasm running afftdn / highpass and is never uploaded; the first use of the workbench downloads about 31–32 MB of ffmpeg core from the site's asset domain or jsDelivr.