var handle;
function overAudio(){
   time = 150;
   bgPos = $('#btn_ascolta').css('backgroundPosition');
   if (bgPos=='0px 0px' || bgPos=='0% 0%') {
      newPos = '0px 20px';
   } else if (bgPos=='0px 20px' || bgPos=='0% 20px') {
      newPos = '0px 40px';
   } else if (bgPos=='0px 40px' || bgPos=='0% 40px') {
      newPos = '0px 0px';
   }
   $('#btn_ascolta').css({'backgroundPosition': newPos});
   handle = setTimeout('overAudio()', time);
}
function outAudio(){
   clearTimeout(handle);
   $('#btn_ascolta').css({backgroundPosition: '0px 0px'});
}