function preload() {
  // set the extensions we have included
  soundFormats('mp3', 'ogg');

  // load either beatbox.mp3 or beatbox.ogg, depending on the browser
  soundFile = loadSound('../files/beatbox.mp3');
}
There is no single audio format that is supported by all
 popular web browsers. Most web browsers support MP3, but
 some (Firefox, Opera) do not because it is a patented codec.

 You can ensure file format compatability by including multiple
 file extensions. Both MP3 and OGG are recommended.