Web Speech API: Unspoken Punctuation

at a glance

why it exists

The existing Web Speech API returns transcript text but does not insert punctuation unless the user explicitly dictates it (e.g. says "Hello comma how are you period"). This produces run-on transcripts that require manual editing before use in prose contexts.

Many speech recognition systems — including mobile dictation on iOS, Android, and Windows — already infer punctuation from prosodic cues: a rising intonation ends with a question mark, a brief pause between clauses inserts a comma, a falling intonation followed by a longer pause inserts a period. The unspokenPunctuation attribute exposes this capability through the Web Speech API, enabling web apps to receive naturally punctuated transcripts without instructing users to speak punctuation aloud.

shape of the API

The property must be set before calling start(). Setting it during recognition has no effect until the next session.

example

const recognition = new SpeechRecognition();
recognition.lang = 'en-US';
recognition.continuous = true;
recognition.interimResults = true;

// Chrome 151+: automatically add punctuation from prosody
recognition.unspokenPunctuation = true;

recognition.onresult = (event) => {
  let transcript = '';
  for (let i = event.resultIndex; i < event.results.length; i++) {
    const result = event.results[i];
    transcript += result[0].transcript;
    if (result.isFinal) {
      // Without unspokenPunctuation: "hello how are you doing today"
      // With unspokenPunctuation:    "Hello, how are you doing today?"
      document.querySelector('#output').textContent += transcript;
    }
  }
};

recognition.start();

browser support

see also

• Chrome Platform Status — Web Speech API: Unspoken Punctuation
• Web Speech API specification