This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
The rate
property of the SpeechSynthesisUtterance
interface gets and sets the speed at which the utterance will be spoken at.
If unset, a default value of 1 will be used.
Syntax
var myRate = speechSynthesisUtteranceInstance.rate; speechSynthesisUtteranceInstance.rate = 1.5;
Value
A float representing the rate value. It can range between 0.1 (lowest) and 10 (highest), with 1 being the default pitch for the current platform or voice, which should correspond to a normal speaking rate. Other values act as a percentage relative to this, so for example 2 is twice as fast, 0.5 is half as fast, etc.
Some speech synthesis engines or voices may constrain the minimum and maximum rates further. If SSML is used, this value will be overridden by prosody tags in the markup.
Examples
var synth = window.speechSynthesis;
var inputForm = document.querySelector('form');
var inputTxt = document.querySelector('input');
var voiceSelect = document.querySelector('select');
var voices = synth.getVoices();
...
inputForm.onsubmit = function(event) {
event.preventDefault();
var utterThis = new SpeechSynthesisUtterance(inputTxt.value);
var selectedOption = voiceSelect.selectedOptions[0].getAttribute('data-name');
for(i = 0; i < voices.length ; i++) {
if(voices[i].name === selectedOption) {
utterThis.voice = voices[i];
}
}
utterThis.rate = 1.5;
synth.speak(utterThis);
inputTxt.blur();
}
Specifications
Specification | Status | Comment |
---|---|---|
Web Speech API The definition of 'rate' in that specification. |
Draft |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
rate | Chrome Full support 33 | Edge Full support 14 | Firefox Full support 49 | IE No support No | Opera Full support 21 | Safari Full support 7 | WebView Android No support No | Chrome Android Full support 33 | Firefox Android
Full support
62
| Opera Android No support No | Safari iOS Full support 7 | 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.