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Dev.to
Dev.to
7/28/2026
Why I measure interview silence with WebAudio, not the Speech API

Why I measure interview silence with WebAudio, not the Speech API

Short summary

A practical explanation of why speech-to-text event timing is unreliable for detecting silence in browser voice apps, and how to measure it acoustically with a WebAudio graph instead. STT timings are polluted by network latency, buffering, and interim-result churn, producing false silence signals. The solution: read RMS loudness from the raw waveform, calibrate a noise floor per room, and apply hysteresis with two thresholds to distinguish thinking pauses from finished answers.

  • STT event timings are unreliable for silence detection due to network latency, buffering, and interim-result churn
  • Measure silence acoustically via WebAudio RMS on the raw microphone waveform instead of inferring from transcription events
  • Calibrate a per-room noise floor and use hysteresis with dual thresholds to separate thinking pauses from done-answering signals

Generated with AI, which can make mistakes.

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