Patients who have seen us for a hearing aid evaluation have heard many of the reasons we give for binaural amplification (a fancy way of saying wearing hearing aids in both ears). At our recent California Academy of Audiology convention, there was a speaker who gave us further insight into the need to be hearing from both ears.
Before I can explain his point I need to give a short anatomy and physiology lesson. Sound is funneled into the ear canal by the outer ear, the eardrum vibrates and makes the little bones move in the middle ear. The final bone moves in and out of the inner ear and makes the fluid in the co- chlea move the organ of Corti. This organ contains the thousands of microscopic hair cells that react to the loudness and pitch of sounds coming into the system. Attached to the end of each hair cell is a nerve fiber that sends information up to the brain.
Are you still with me? I haven’t even gotten to the binaural part yet!
Once the message is sent from the hair cell, there are multiple pathways the message will take. One path is directly up to the auditory cortex on the side of the brain where the stimulus occurs (hair cell in right ear sends message up to auditory cortex on the right side of the brain). Another pathway takes the sound from one side and crosses over to the auditory cortex on the opposite side of the brain (hair cell in right ear sends message to the auditory cortex on the left side of the brain).
By getting this complete message to both sides of the brain, we can handle more complex auditory input. A person sitting in quiet talking to one other person with no background noise may do fine with one hearing aid. A person in a crowd listening to several talkers will be at a distinct disadvantage with only one hearing aid because their brain isn’t getting the full message.
Other reasons that we commonly cite for wearing two aids include better localization of sound and less need for loud volume in one ear. This means better sound quality and less of a chance for feedback. Finally, keeping both ears stimulated lessens the impact of auditory deprivation on the hearing system.
Some of our patients cannot wear an aid on one ear or only have hearing loss in one ear. If you are wearing only one aid and you wonder if you should have two, make an appointment with your audiologist.