SpeechSynthesisUtterance.voice

The voice property of the SpeechSynthesisUtterance interface gets and sets the voice that will be used to speak the utterance.

This should be set to one of the SpeechSynthesisVoice objects returned by SpeechSynthesis.getVoices(). If not set by the time the utterance is spoken, the voice used will be the most suitable default voice available for the utterance's lang setting.

var myVoice = speechSynthesisUtteranceInstance.voice;
speechSynthesisUtteranceInstance.voice = speechSynthesisVoiceInstance;

A SpeechSynthesisVoice object.

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

• Web Speech API