var soundStatusPlaying = (window.parent.frames['frame_sound'].location.href.indexOf('NoSound') == -1);

function stopSound() {
  changeImages('sound_image','img/sound-still.gif');
  window.parent.frames['frame_sound'].location.href = 'http://www.urbangallery.es/main/sound.php?NoSound=1';
  soundStatusPlaying = false;
}

function startSound() {
  changeImages('sound_image','img/sound.gif');
  window.parent.frames['frame_sound'].location.href = 'http://www.urbangallery.es/main/sound.php';
  soundStatusPlaying = true;
}

function switchSoundStatus() {
  if (soundStatusPlaying) stopSound(); else startSound();
}

function updateSoundImageStatus() {
  if (soundStatusPlaying) changeImages('sound_image','img/sound.gif'); else changeImages('sound_image','img/sound-still.gif');
}