function compute (obj) {

		with (Math) {

		d1=eval(obj.distance1.value);
		d2=eval(obj.distance2.value);
		s1=eval(obj.sound1.value);
		s2=eval(obj.sound2.value);

		x=d1 / d2;

		y=20*(0.43429*log(x));

		s2=y+s1

		a=s2*10;
		b=Math.round(a);
		c=(b / 10);

		obj.sound2.value =c;
		 }	
		}