In the autumn of 2011, I had 4 weeks of Cisplatin, before I was switched to 2 weeks of Carboplatin. The low level ringing in my ears began even before I stated my treatment, but it certainly became more discernable as my treatment progressed.
It has never actually tailed off, but then again it has never got any worse, even after 18 weeks of Cisplatin this summer - and this was triple the strength of my dose in 2011.
As I sit here now, in a quiet house before my wife and daughter come home, I can detect the faint fuzzy ringing in my ears. However, on a day to day basis I don't really notice it. I may miss the odd word and my wife occasionally points out that I have the volume on the TV too high, but it's not something that bothers me too much.
Hope your tinnitus if it does surface again is similarly manageable - my Consultants gave me the impression that it was just one of those things I had to accept.