Rush Limbaugh's Voice is Changing due to..

I don't mean this as a goof on Rush, but have you noticed the difference in Rush's voice, specifically the higher register tones when he gets a little emotional(The lower tones sound the same)? I find the new sound of his voice a little annoying. It sounds like Phil Hendrie doing an impression of Rush. I've heard Rush has been losing/or has lost much of his hearing, so I assume it's due to that. If it gets any worse, I wonder if he'll continue to broadcast?