My audiogram for a Class I has been marginal for a few years now - I am on an annual audio for my medical. When it first occured I was required to provide a report from a training captain and/or chief flying instructor that my hearing loss was not causing any problems during flight. This was duly provided without any problems.
As an aside though I can copy VOLMET and ATC Comms in conditions of considerable interference (mush) when my younger counterparts are unable to do so!