Experimental
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
BCD tables only load in the browser