The voice isn't deeper, it's actually like someone faking having a deep voice. He used to have that great voice as descibed in Post #78. Maybe it changed because of the weight loss so now he's trying to recapture it artificially.
He needs a vocal coach and doctor ASAP, especially after hearing him after the WTC bombing. Everyone noticed it more post-WTC because the seemingly arrogant tone sounds so inappropriate after all that just happened.
I noticed the same thing too. Something is very wrong here. This just can't be Rush.