SpeechSynthesisUtterance

The SpeechSynthesisUtterance interface of the Web Speech API represents a speech request. It contains the content the speech service should read and information about how to read it (e.g. language, pitch and volume.)

SpeechSynthesisUtterance.SpeechSynthesisUtterance()

Returns a new SpeechSynthesisUtterance object instance.

SpeechSynthesisUtterance also inherits properties from its parent interface, EventTarget.

SpeechSynthesisUtterance.lang

Gets and sets the language of the utterance.

SpeechSynthesisUtterance.pitch

Gets and sets the pitch at which the utterance will be spoken at.

SpeechSynthesisUtterance.rate

Gets and sets the speed at which the utterance will be spoken at.

SpeechSynthesisUtterance.text

Gets and sets the text that will be synthesised when the utterance is spoken.

SpeechSynthesisUtterance.voice

Gets and sets the voice that will be used to speak the utterance.

SpeechSynthesisUtterance.volume

Gets and sets the volume that the utterance will be spoken at.

SpeechSynthesisUtterance.onboundary

Fired when the spoken utterance reaches a word or sentence boundary.

SpeechSynthesisUtterance.onend

Fired when the utterance has finished being spoken.

SpeechSynthesisUtterance.onerror

Fired when an error occurs that prevents the utterance from being succesfully spoken.

SpeechSynthesisUtterance.onmark

Fired when the spoken utterance reaches a named SSML "mark" tag.

SpeechSynthesisUtterance.onpause

Fired when the utterance is paused part way through.

SpeechSynthesisUtterance.onresume

Fired when a paused utterance is resumed.

SpeechSynthesisUtterance.onstart

Fired when the utterance has begun to be spoken.

In our basic Speech synthesiser demo, we first grab a reference to the SpeechSynthesis controller using window.speechSynthesis. After defining some necessary variables, we retrieve a list of the voices available using SpeechSynthesis.getVoices() and populate a select menu with them so the user can choose what voice they want.

Inside the inputForm.onsubmit handler, we stop the form submitting with preventDefault(),  use the constructor to create a new utterance instance containing the text from the text <input>, set the utterance's voice to the voice selected in the <select> element, and start the utterance speaking via the SpeechSynthesis.speak() method.

var synth = window.speechSynthesis;

var inputForm = document.querySelector('form');
var inputTxt = document.querySelector('input');
var voiceSelect = document.querySelector('select');

var voices = synth.getVoices();

for(i = 0; i < voices.length ; i++) {
  var option = document.createElement('option');
  option.textContent = voices[i].name + ' (' + voices[i].lang + ')';
  option.setAttribute('data-lang', voices[i].lang);
  option.setAttribute('data-name', voices[i].name);
  voiceSelect.appendChild(option);
}

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];
    }
  }
  synth.speak(utterThis);
  inputTxt.blur();
}

• Web Speech API