DEV Community

Discussion on: I Built a Voice AI with Sub-500ms Latency. Here's the Echo Cancellation Problem Nobody Talks About

Collapse
 
nimrodkra profile image
Nimrod Kramer

solid deep dive into the audio pipeline challenges! the echo cancellation problem is brutal - we've tackled similar issues in some of the voice projects we've covered on daily.dev. your two-tier RMS gate approach works well, especially the cooldown period accounting for room resonance decay. the filler audio insight is spot on - silence feels broken in voice conversations. have you experimented with adaptive thresholds based on room acoustics? some setups we've seen dynamically adjust the RMS thresholds based on initial background noise measurement during session setup.

Collapse
 
remi_etien profile image
Konstantin

Great question about adaptive thresholds! We considered dynamic calibration during session setup, but went a different route. The problem: background noise is a snapshot — user moves rooms, opens a window, kid starts playing — and your baseline is stale.

What worked: a fixed two-tier approach. RMS 0.03 as the speech/silence boundary (we started at 0.01 — took us a while to realize background noise sits at 0.01-0.02 and was triggering false positives). Then a separate echo gate at RMS 0.05 that activates during agent speech with a 1.5s cooldown for room resonance decay. That cooldown value was hard-won — the echo gate is what catches residual artifacts that browser AEC misses and that would otherwise crash Gemini's Live API with 1011 errors.

If you look at our commit history, it's basically a graveyard of approaches: silence injection, manual VAD, audioStreamEnd timing, adaptive thresholds — we tried everything before settling on the simple static thresholds that just work. Sometimes boring is better