random-voices.js

function randomizeVoice(text, callback) {
  const voices = window.speechSynthesis.getVoices();
  const words = text.split(' ');
  sayWords(words, voices, callback);
}

function sayWords(words, voices, callback) {
  if (words.length === 0) return callback();
  var voice = voices[Math.round(Math.random() * voices.length)];
  sayWord(words[0], voice, () => sayWords(words.slice(1), voices));
}


function sayWord(word, voice, callback) {
  var message = new SpeechSynthesisUtterance();
  message.text = word;
  message.voice = voice;
  message.rate = 0.9;
  message.lang = 'en-US';
  message.addEventListener('end', callback);
  window.speechSynthesis.speak(message);
}