Which ear (right or left)?
There is a thread going about this issue, by the way.
One thing I'll say is that I've had a very strong issue with this, and my path isn't mediumship at all. I'm more a yogi - meditation, dreamwork, Reiki and other "energy work", etc. I've had this as a recurrent problem over a period of about eight years or so - because it would diminish my ability to hear what people (ordinary, incarnate people) were saying. It hasn't been a medical thing or a mechanical thing like earwax build-up.
And some of the people complaining about loud sounds in their ear, on the thread I mentioned, associate the phenomenon not with mediumship or an outcome of meditation
per se but with the Twin Soul idea.