Well it's not 'official' but I can definitely tell you that ZAC can hear! (maybe some minor hearing loss?)...He had some drainage from his ear a couple of weeks ago and since then he has been so sensitive to various noises that he didn't seem to be phased by before!
He's sleeping in his own room (with Tyler since they share a room) now. He needs the sounds of the sound machine to help him to sleep (so unlike his daddy, who needs complete quiet!)
He took his first trip to the Denver Zoo yesterday too...I'll have to upload some pics and add a post about that later on