JQery /HTML5 Audio file Fade 2

JQery /HTML5 Audio file Fade 2

Hi
OK after much tinkering I've given up. An descriptionof what I'd like to achieve: User scrolls down the page the sound fades in. Scroll up the page the sound fades out. I want to be able to control (more or less) at what point on the scroll the sound fades in/out. Please be aware there are other sounds playing as well I don't want to affect if possible. If this proves too difficult then I don't care if the others sounds fade out as well.

I'm using a specific plugin called volumizer found on post called 

JQery /HTML5 Audio file Fade out



Here is some code that doesn't work at all but it give you and idea of what I'm trying for:

HTML:

      <audio loop id="soundTour3" src="audio/smooth_beat.mp3"></audio>
 

JAVASCRIPT:

</script><script type="text/javascript" charset="utf-8">
 $(document).ready(function() {
    var audioElm = $('#soundTour3').get(0);
audioElm.volume = 0 
    audioElm.play();

});
$(window).scroll(function(){
  // gets the position of the window
          var y = $(window).scrollTop();
   
          if( y > (500) ){
            $('#soundTour3').volumizer({1:[5,10000]})
   if( y < (500) ){
           $('#soundTour3').volumizer({1:[5,.0001]})
         
});

</script>