Vanessa, I am the one who had the Cisplatin and had serious hearing changes. If he is on that drug, get him off of it PDQ. For some people, less than 1%, it will cause complete hearing loss. The way my chemo oncologist put it was he didn't want to cure the cancer and have me end up deaf as a post. This is not a joke. If he is on chemo, you must call the doc right now!
Addendum:
My hearing is absolutely top notch now, and returned to normal when I stopped the Cisplatin and switched to other poisons.