It shouldn't have any sound, though I suppose you could have an electronic squeal come from something thats down circuit from it. You normally find leaking caps by looking at them. Any that are bulging or having brown stuff stuck on top are bad. Here are some pics.
Yeah thats correct as far as i know there should be no noise coming from the cap never heard of that, if there is physical swelling or leaking then rather use that as reference also if it is an electrical sound of some sort rather look at the power supply if you are trying to find the problem using a issue with sound? what exactly is the problem lets see if we can help with that.