SpeechSynthesisUtterance

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2018.

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.)

Constructor

SpeechSynthesisUtterance(): Returns a new SpeechSynthesisUtterance object instance.

Instance properties

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 synthesized 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.

Events

Listen to these events using addEventListener() or by assigning an event listener to the oneventname property of this interface.

boundary: Fired when the spoken utterance reaches a word or sentence boundary. Also available via the onboundary property.
end: Fired when the utterance has finished being spoken. Also available via the onend property.
error: Fired when an error occurs that prevents the utterance from being successfully spoken. Also available via the onerror property
mark: Fired when the spoken utterance reaches a named SSML "mark" tag. Also available via the onmark property.
pause: Fired when the utterance is paused part way through. Also available via the onpause property.
resume: Fired when a paused utterance is resumed. Also available via the onresume property.
start: Fired when the utterance has begun to be spoken. Also available via the onstart property.

Examples

In our basic Speech synthesizer 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.

const synth = window.speechSynthesis;

const inputForm = document.querySelector("form");
const inputTxt = document.querySelector("input");
const voiceSelect = document.querySelector("select");

let voices;

function loadVoices() {
  voices = synth.getVoices();
  for (let i = 0; i < voices.length; i++) {
    const option = document.createElement("option");
    option.textContent = `${voices[i].name} (${voices[i].lang})`;
    option.value = i;
    voiceSelect.appendChild(option);
  }
}

// in Google Chrome the voices are not ready on page load
if ("onvoiceschanged" in synth) {
  synth.onvoiceschanged = loadVoices;
} else {
  loadVoices();
}

inputForm.onsubmit = (event) => {
  event.preventDefault();

  const utterThis = new SpeechSynthesisUtterance(inputTxt.value);
  utterThis.voice = voices[voiceSelect.value];
  synth.speak(utterThis);
  inputTxt.blur();
};

Specifications

Specification
Web Speech API # speechsynthesisutterance

Browser compatibility

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