Please talk to the doctor and have them check his ears again, and if it does not have anything to do with his hearing consider this. My son did this also and now is 8 years old. We now know that this is a sensory issue and he has extrememly hightened senses. Certain sounds bother him that we would consider not to be the slighest bit bothersome to us. We now know that it can be part of a more serious problem. If the regular pediatrician says it is nothing and your son continues to do this try checking into it with an occuapational therapist or a developmental pediatrician who knows a lot about sensory integration issues. I am a big advocate for early intervention with children. I hope I have helped in someway. Does he seem to be overwhelmed when you are out in public when the sounds maybe louder?
A little about me: married, mother of 2 boys, 4 and 8