filterEnv = function(wad, arg){
	wad.filter.forEach(function (filter, index){
		filter.node.frequency.linearRampToValueAtTime(filter.frequency, arg.exactTime);
		filter.node.frequency.linearRampToValueAtTime(filter.env.frequency, arg.exactTime + filter.env.attack);
	});
}
When a note is played, these two functions will schedule changes in volume and filter frequency,
as specified by the volume envelope and filter envelope *