Search cerumen AKA ear wax.
Parents are often very concerned about the amount of ear wax that oozes out of their child's ears.
Likewise, they tend to be apologetic when the doctor has to clean out the wax to view the eardrums. Cerumen is nature's way of keeping the ear canals clean. The stuff acumulates until it simply balls up and falls out of the ear canal in the course of normal chewing and talking motion of the jaw. The only reason your doctor cleans out the wax is that the eardrum must be visualised for a thorough physical exam in a young child. It is not done so that the child can hear better - he hears just fine through and around the wax.