Finger on iPhone Speaker Was Tricking AI Avatar's Voice Detection System

A voice dialogue avatar that worked correctly on PC was repeatedly cutting itself off on iPhone Safari due to a subtle audio glitch. Covering the phone's speaker with a finger while the avatar spoke disrupted the browser's echo canceller, causing residual sound to leak into the microphone. The voice activity detector (VAD) mistook this leaked audio for human speech and triggered false interrupts every two seconds, though no transcription was produced since the sound contained no words. The fix involved raising the minimum continuous speech duration required to trigger an interrupt — from 0.2 to 0.5 seconds — only during avatar playback, so brief echo artifacts are filtered out without slowing normal turn-taking. Research from LiveKit supported this approach, showing that analyzing roughly 216ms of audio before acting on a VAD signal rejects over half of false interrupt triggers.