I hope you let him know you want to let him know what's true and what isn't. He may be experiencing hearing voices -- or not. If he is, it can make someone feel very suspicious of all sounds he hears.
Some of those sounds are probably real: The sounds created by Skype and other connections are very strange, like wind or a fan, or electronic sound or other things. Both sides of the call don't usually hear the same thing. Just my guess that some of the weird sounds he hears when skypeing you are due to this. I hear added sounds often on Skype, whether the person is an hour away, or a continent away.