I was also on Cisplatin with radiation concurrently. Hearing loss is listed as one of the possible side effects. A month after my completion, I experienced sudden ringing sound (like that a train was moving right next to you ) for two seconds, several times a day. This lasted for about two months and disappeared unnoticeably. My oncologist told me that since the targets of radiation were not very close to my ears (mine is tonsil cancer spread to lymph nodes on neck), there shouldn't be any damage to hearing. I have heard that a nasopharynx cancer patient had his ear drum damaged when taking his flight due to enormous air pressure when taking off) a short time after completing the therapy. So ask your oncologist about this hearing issue.