I have a childhood hearing loss in my left ear. Drs said due to ear infections most likely.  I think mumps since I had mumps at age 8-9 on one side of face only and only one ear with loss.  Right ear tested normal thru adulthood. At 45 had brain surgery for a benign meningioma on my facial nerve and as result lost all hearing in my good ear.  I’ve been wearing aid on the left ear only since 2007.  I’m waiting for cros technology to get perfected and make my life awesome!