FFmpeg afftdn denoiser + high/low-pass presets for clean voice tracks.

How the Voice preset cleans a noisy memo

This background noise remover strips steady noise — fans, fridges, hiss — from voice recordings using FFmpeg's afftdn denoiser plus high-pass and low-pass filters, all in your browser. Walk through a real case: a voice memo recorded beside a laptop fan. The fan's rumble sits below 80 Hz, so the Voice preset's high-pass cuts it outright; tape hiss above 12,000 Hz goes to the low-pass. In the mid-band, afftdn estimates the noise floor and subtracts it — the preset literally reads nr=12, nf=-25, meaning 12 dB of reduction toward a -25 dB floor. That's the whole recipe, and it fixes most room-noise recordings in one pass.

Resist the urge to start with Aggressive. It doubles the reduction to 18 dB at a -30 dB floor, and on thin phone audio that's where voices start sounding underwater. The Mild clean preset skips the denoiser entirely — it's just a 60 Hz high-pass and a 15,000 Hz low-pass — so if your only problem is rumble or hiss, not broadband hum, Mild keeps the most natural tone. Always A/B the output against the original before downloading; your ears catch artifacts a waveform won't.