This is an experimental technology
Because this technology's specification has not stabilized, check the compatibility table for the proper prefixes to use in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future versions of browsers as the spec changes.

The start event of the Web Speech API SpeechSynthesisUtterance object is fired when the utterance has begun to be spoken.

Bubbles No
Cancelable No
Target objects SpeechSynthesisUtterance
Interface SpeechSynthesisEvent


utterThis.onstart = function(event) {
  console.log('We have started uttering this speech: ' + event.utterance.text);


The start event implements the SpeechSynthesisEvent interface, which inherits from Event. It therefore has available the properties and methods defined on both these interfaces.


Specification Status Comment
Web Speech API
The definition of 'speech synthesis utterance events' in that specification.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support 33 44 (44) [1] Not supported Not supported Not supported
Feature Android Chrome Firefox Mobile (Gecko) Firefox OS IE Phone Opera Mobile Safari Mobile
Basic support ? (Yes) ? 2.5 Not supported Not supported Not supported
  • [1] Can be enabled via the media.webspeech.synth.enabled flag in about:config.

See also

Document Tags and Contributors

 Contributors to this page: chrisdavidmills
 Last updated by: chrisdavidmills,