Overlay two tracks so they play at the same time — like adding background music under narration — with independent volume control for each.
The Audio Mixer overlays two recordings into one: a voice-over on a music bed, a sound effect on dialogue, or two instruments recorded separately. You control each level in dB, when Track B starts, whether it loops to cover Track A, and automatic ducking.
Ducking lowers the music while the voice is speaking and lets it swell back in the gaps — the same technique radio and podcasts use so speech stays intelligible without manually riding faders.
Both tracks are summed sample by sample after applying their gains, with Track B offset by your start time. For ducking, an envelope follower on Track B (30 ms attack, 400 ms release) decides when B is audible (above −45 dBFS) and drives a smooth gain reduction on Track A. A final true-peak limiter at −1 dBTP prevents the sum from clipping.
Put narration over background music with automatic ducking.
Layer effects with dialogue.
Combine separately recorded parts.
Place a jingle under a voice read.
| Tracks | 2 |
|---|---|
| Level range | −30 to +12 dB each |
| Ducking | 0–24 dB, 30 ms attack / 400 ms release |
| Safety | True-peak limiter |
Mix two, download, and mix the result with a third.
Automatic lowering of one track while another is playing.
The output is as long as the longer of the two — the shorter track simply stops playing partway through and silence fills the rest.
Not in this version — both tracks start at the same time (0:00). Use the Audio Cutter or Trimmer first if you need one track to start partway through the other.
This tool runs entirely in your browser using the Web Audio API. Nothing is uploaded, stored or shared — there is no server to send your file to, so it works offline once the page has loaded.
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