Ok, so i've stolen the "rain" effect from Ghost Shooter "rain demo" sample, i made it random by making it only trigger once every random seconds (plus adding wait -> destroy at the end).
Here the code, you can see in red the parts i've modified/added:
<img src="http://imageshack.com/a/img843/2329/c8q0.jpg" border="0" />
My problem is, i didn't manage to properly add the sound loop to it: no matter what try, i can't make the sound start and END syncronized with the rain effect.
Any advice?