Web Speech Synthesis API（音声合成API） を試す ref: http://qiita.com/ikr7/items/71406123c991a05ed8ba

file0.js

var helloworld = new SpeechSynthesisUtterance('Hello, World!');

helloworld.lang = 'en-US';

speechSynthesis.speak(helloworld);

file1.js

var japanese = new SpeechSynthesisUtterance('ひだまりスケッチの宮子ちゃんのおしっこ');

japanese.lang = 'ja-JP';

speechSynthesis.speak(japanese);