{
  "id": 7670143,
  "title": "スマホの指がエコーキャンセラを壊していた — 音でないもので発話が切れる",
  "url": "https://urgent.news/2026/09/16/story-7670143",
  "topic": "tech",
  "section": "Tech",
  "published": "2026-09-16T00:40:52.000Z",
  "source": {
    "name": "Dev.to",
    "slug": "dev-to",
    "url": "https://dev.to/orca_forge/sumahonozhi-gaekokiyanserawohuai-siteita-yin-denaimonodefa-hua-gaqie-reru-2lo2"
  },
  "original_language": "en",
  "account": "The iPhone Safari browser on iPhones stopped working with a voice dialogue avatar when used on mobile devices. The issue stemmed from the browser's echo canceller being unable to handle sudden changes in sound when the user covered the speaker with their finger, causing the browser's echo canceller to misinterpret the residual sound as human speech. This led to the avatar repeatedly starting and stopping its speech at two-second intervals.\n\nUpon examining the logs, a pattern emerged: a speech start was detected 5 milliseconds before the avatar stopped speaking, and this occurred in all five instances. The decisive factor was that no transcription was output, as the sound was not recognized as a word.\n\nThe root cause was the browser's automatic gain control (AEC) not being able to cancel out the echo during playback, leading to the residual sound leaking out. This misinterpretation was seen by the voice activity detector (VAD) as human speech, causing the avatar to stop speaking repeatedly.\n\nThe author had previously implemented a gate as a countermeasure against self-echo, which drops speech immediately after the sound finishes. However, this gate did not work in this scenario, as it was designed to let through speech during playback to prevent interrupting the speech.\n\nFurthermore, the author investigated how other web services handle this issue. They found that LiveKit, a web service that keeps the microphone open for conversation, waits for the first few hundred milliseconds of speech before making a judgment, which helps to reject 51% of VAD-based interrupts. However, no silver bullet solution exists for the echo itself, and most solutions rely on the browser's standard automatic gain control, which is a common premise on desktop PCs but not on mobile devices.",
  "summary": "📝 Originally published (in Japanese) at forge.workstyle.tech . The Avatar that Stopped Working on iPhone Safari The voice dialogue avatar that worked fine on PC had an issue on iPhone Safari. The avatar seems to be reacting to its own speech. It also seems to be reacting when the speaker's volume changes while operating the smartphone. What the Logs Showed Looking at the judgment records, a…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}