Cómo utilizarSpeechSynthesisUtterance() ywindow.speechSynthesis.speak() en el navegador de cromo?

var msg = new SpeechSynthesisUtterance( "Hello I am browser" );
window.speechSynthesis.speak( msg );

no produce salida en los altavoces del sistema.

Se han observado problemas con la APILa API HTML5 SpeechSynthesis es basura;

var voices = window.speechSynthesis.getVoices();

registra una matriz vacía paravoices identificador y solo el cromo, no el cromo, supuestamente es compatibleWeb Speech API Specification, elWeb Speech API Demostración establece el valor dehtml elemento en la demostración para el enunciado expresado cuando el micrófono está habilitado en la página.

Al menos parte del JavaScript relacionado con la funcionalidad es aparentemente

var langs =
[['Afrikaans',       ['af-ZA']],
 ['Bahasa Indonesia',['id-ID']],
 ['Bahasa Melayu',   ['ms-MY']],
 ['Català',          ['ca-ES']],
 ['Čeština',         ['cs-CZ']],
 ['Dansk',           ['da-DK']],
 ['Deutsch',         ['de-DE']],
 ['English',         ['en-AU', 'Australia'],
                     ['en-CA', 'Canada'],
                     ['en-IN', 'India'],
                     ['en-NZ', 'New Zealand'],
                     ['en-ZA', 'South Africa'],
                     ['en-GB', 'United Kingdom'],
                     ['en-US', 'United States']],
 ['Español',         ['es-AR', 'Argentina'],
                     ['es-BO', 'Bolivia'],
                     ['es-CL', 'Chile'],
                     ['es-CO', 'Colombia'],
                     ['es-CR', 'Costa Rica'],
                     ['es-EC', 'Ecuador'],
                     ['es-SV', 'El Salvador'],
                     ['es-ES', 'España'],
                     ['es-US', 'Estados Unidos'],
                     ['es-GT', 'Guatemala'],
                     ['es-HN', 'Honduras'],
                     ['es-MX', 'México'],
                     ['es-NI', 'Nicaragua'],
                     ['es-PA', 'Panamá'],
                     ['es-PY', 'Paraguay'],
                     ['es-PE', 'Perú'],
                     ['es-PR', 'Puerto Rico'],
                     ['es-DO', 'República Dominicana'],
                     ['es-UY', 'Uruguay'],
                     ['es-VE', 'Venezuela']],
 ['Euskara',         ['eu-ES']],
 ['Filipino',        ['fil-PH']],
 ['Français',        ['fr-FR']],
 ['Galego',          ['gl-ES']],
 ['Hrvatski',        ['hr_HR']],
 ['IsiZulu',         ['zu-ZA']],
 ['Íslenska',        ['is-IS']],
 ['Italiano',        ['it-IT', 'Italia'],
                     ['it-CH', 'Svizzera']],
 ['Lietuvių',        ['lt-LT']],
 ['Magyar',          ['hu-HU']],
 ['Nederlands',      ['nl-NL']],
 ['Norsk bokmål',    ['nb-NO']],
 ['Polski',          ['pl-PL']],
 ['Português',       ['pt-BR', 'Brasil'],
                     ['pt-PT', 'Portugal']],
 ['Română',          ['ro-RO']],
 ['Slovenščina',     ['sl-SI']],
 ['Slovenčina',      ['sk-SK']],
 ['Suomi',           ['fi-FI']],
 ['Svenska',         ['sv-SE']],
 ['Tiếng Việt',      ['vi-VN']],
 ['Türkçe',          ['tr-TR']],
 ['Ελληνικά',        ['el-GR']],
 ['български',       ['bg-BG']],
 ['Pусский',         ['ru-RU']],
 ['Српски',          ['sr-RS']],
 ['Українська',      ['uk-UA']],
 ['한국어',            ['ko-KR']],
 ['中文',             ['cmn-Hans-CN', '普通话 (中国大陆)'],
                     ['cmn-Hans-HK', '普通话 (香港)'],
                     ['cmn-Hant-TW', '中文 (台灣)'],
                     ['yue-Hant-HK', '粵語 (香港)']],
 ['日本語',           ['ja-JP']],
 ['हिन्दी',            ['hi-IN']],
 ['ภาษาไทย',         ['th-TH']]];

for (var i = 0; i < langs.length; i++) {
  select_language.options[i] = new Option(langs[i][0], i);
}
select_language.selectedIndex = 7;
updateCountry();
select_dialect.selectedIndex = 6;
showInfo('info_start');

function updateCountry() {
  for (var i = select_dialect.options.length - 1; i >= 0; i--) {
    select_dialect.remove(i);
  }
  var list = langs[select_language.selectedIndex];
  for (var i = 1; i < list.length; i++) {
    select_dialect.options.add(new Option(list[i][1], list[i][0]));
  }
  select_dialect.style.visibility = list[1].length == 1 ? 'hidden' : 'visible';
}

var create_email = false;
var final_transcript = '';
var recognizing = false;
var ignore_onend;
var start_timestamp;
if (!('webkitSpeechRecognition' in window)) {
  upgrade();
} else {
  start_button.style.display = 'inline-block';
  var recognition = new webkitSpeechRecognition();
  recognition.continuous = true;
  recognition.interimResults = true;

  recognition.onstart = function() {
    recognizing = true;
    showInfo('info_speak_now');
    start_img.src = '/intl/en/chrome/assets/common/images/content/mic-animate.gif';
  };

  recognition.onerror = function(event) {
    if (event.error == 'no-speech') {
      start_img.src = '/intl/en/chrome/assets/common/images/content/mic.gif';
      showInfo('info_no_speech');
      ignore_onend = true;
    }
    if (event.error == 'audio-capture') {
      start_img.src = '/intl/en/chrome/assets/common/images/content/mic.gif';
      showInfo('info_no_microphone');
      ignore_onend = true;
    }
    if (event.error == 'not-allowed') {
      if (event.timeStamp - start_timestamp < 100) {
        showInfo('info_blocked');
      } else {
        showInfo('info_denied');
      }
      ignore_onend = true;
    }
  };

  recognition.onend = function() {
    recognizing = false;
    if (ignore_onend) {
      return;
    }
    start_img.src = '/intl/en/chrome/assets/common/images/content/mic.gif';
    if (!final_transcript) {
      showInfo('info_start');
      return;
    }
    showInfo('');
    if (window.getSelection) {
      window.getSelection().removeAllRanges();
      va,r range = document.createRange();
      range.selectNode(document.getElementById('final_span'));
      window.getSelection().addRange(range);
    }
    if (create_email) {
      create_email = false;
      createEmail();
    }
  };

  recognition.onresult = function(event) {
    var interim_transcript = '';
    if (typeof(event.results) == 'undefined') {
      recognition.onend = null;
      recognition.stop();
      upgrade();
      return;
    }
    for (var i = event.resultIndex; i < event.results.length; ++i) {
      if (event.results[i].isFinal) {
        final_transcript += event.results[i][0].transcript;
      } else {
        interim_transcript += event.results[i][0].transcript;
      }
    }
    final_transcript = capitalize(final_transcript);
    final_span.innerHTML = linebreak(final_transcript);
    interim_span.innerHTML = linebreak(interim_transcript);
    if (final_transcript || interim_transcript) {
      showButtons('inline-block');
    }
  };
}

function upgrade() {
  start_button.style.visibility = 'hidden';
  showInfo('info_upgrade');
}

var two_line = /\n\n/g;
var one_line = /\n/g;
function linebreak(s) {
  return s.replace(two_line, '<p></p>').replace(one_line, '<br>');
}

var first_char = /\S/;
function capitalize(s) {
  return s.replace(first_char, function(m) { return m.toUpperCase(); });
}

function createEmail() {
  var n = final_transcript.indexOf('\n');
  if (n < 0 || n >= 80) {
    n = 40 + final_transcript.substring(40).indexOf(' ');
  }
  var subject = encodeURI(final_transcript.substring(0, n));
  var body = encodeURI(final_transcript.substring(n + 1));
  window.location.href = 'mailto:?subject=' + subject + '&body=' + body;
}

function copyButton() {
  if (recognizing) {
    recognizing = false;
    recognition.stop();
  }
  copy_button.style.display = 'none';
  copy_info.style.display = 'inline-block';
  showInfo('');
}

function emailButton() {
  if (recognizing) {
    create_email = true;
    recognizing = false;
    recognition.stop();
  } else {
    createEmail();
  }
  email_button.style.display = 'none';
  email_info.style.display = 'inline-block';
  showInfo('');
}

function startButton(event) {
  if (recognizing) {
    recognition.stop();
    return;
  }
  final_transcript = '';
  recognition.lang = select_dialect.value;
  recognition.start();
  ignore_onend = false;
  final_span.innerHTML = '';
  interim_span.innerHTML = '';
  start_img.src = '/intl/en/chrome/assets/common/images/content/mic-slash.gif';
  showInfo('info_allow');
  showButtons('none');
  start_timestamp = event.timeStamp;
}

function showInfo(s) {
  if (s) {
    for (var child = info.firstChild; child; child = child.nextSibling) {
      if (child.style) {
        child.style.display = child.id == s ? 'inline' : 'none';
      }
    }
    info.style.visibility = 'visible';
  } else {
    info.style.visibility = 'hidden';
  }
}

var current_style;
function showButtons(style) {
  if (style == current_style) {
    return;
  }
  current_style = style;
  copy_button.style.display = style;
  email_button.style.display = style;
  copy_info.style.display = 'none';
  email_info.style.display = 'none';
}

atribuido a los autores del documento.

Aunque no estoy seguro de cómo esto afecta el uso deSpeechSynthesisUtterance() ywindow.speechSynthesis.speak()?

Cómo cargar voces para poblarwindow.speechSynthesis.getVoices()?

¿Cómo implementa el documento de demostración vinculado la funcionalidad para transcribir voz a texto?

¿Cuáles son las soluciones necesarias para usar la API de Web Speech en el navegador Chrome?

Específicamente, ¿cómo transcribir voz a texto y convertir texto a salida de audio?