Web/API/SpeechSynthesis/onvoiceschanged

This is an experimental technologyCheck the Browser compatibility table carefully before using this in production.

The onvoiceschanged property of the SpeechSynthesis interface represents an event handler that will run when the list of SpeechSynthesisVoice objects that would be returned by the SpeechSynthesis.getVoices() method has changed (when the voiceschanged event fires.)

This may occur when speech synthesis is being done on the server-side and the voices list is being determined asynchronously, or when client-side voices are installed/uninstalled while a speech synthesis application is running.

Syntax

speechSynthesisInstance.onvoiceschanged = function() { ... };

Examples

This could be used to populate a list of voices that the user can choose between when the event fires (see our Speak easy synthesis demo.) Note that Firefox doesn't support it at present, and will just return a list of voices when SpeechSynthesis.getVoices() is fired. With Chrome however, you have to wait for the event to fire before populating the list, hence the bottom if statement seen below.

var voices = [];

function populateVoiceList() {
  voices = synth.getVoices();

  for(i = 0; i < voices.length ; i++) {
    var option = document.createElement('option');
    option.textContent = voices[i].name + ' (' + voices[i].lang + ')';
    
    if(voices[i].default) {
      option.textContent += ' -- DEFAULT';
    }

    option.setAttribute('data-lang', voices[i].lang);
    option.setAttribute('data-name', voices[i].name);
    voiceSelect.appendChild(option);
  }
}

populateVoiceList();
if (speechSynthesis.onvoiceschanged !== undefined) {
  speechSynthesis.onvoiceschanged = populateVoiceList;
}

Specifications

Specification	Status	Comment
Web Speech APIThe definition of 'onvoiceschanged' in that specification.	Draft

Browser compatibility

Update compatibility data on GitHub

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`onvoiceschanged` Experimental'	Chrome Full support 33	Edge Full support 14	Firefox Full support 49	IE No support No	Opera No support No	Safari No support No	WebView Android Full support 4.4.3	Chrome Android Full support 33	Firefox Android Full support 62 Full support 62 No support 61 — 62 Disabled' Disabled' From version 61 until version 62 (exclusive): this feature is behind the `media.webspeech.synth.enabled` preference (needs to be set to `true`). To change preferences in Firefox, visit about:config.	Opera Android No support No	Safari iOS No support No	Samsung Internet Android Full support 3.0

Legend

Full support: Full support
No support: No support
Experimental. Expect behavior to change in the future.': Experimental. Expect behavior to change in the future.
User must explicitly enable this feature.': User must explicitly enable this feature.