Creating Realistic Hearing Aid Expectations
Wearing a hearing aid is exactly what it says – an AID. It will not replace your hearing but will aid you in hearing better. It is for this reason that it is important to have realistic expectations in terms of how a hearing aid can assist you taking into account the levels of damage and auditory deprivation in your ear.
Our ears are made up of three parts namely the outer ear, middle ear and inner ear. Inside the inner ear is our cochlea which is our hearing organ. The cochlea is filled with thousands of hair cells which vibrate in the presence of sound. These hair cells act as sensory receptors and are the link between the ear and the brain and therefore the most important aspects of our auditory system.
Inside the cochlea we have two different types of hair cells namely outer and inner hair cells. We have three rows of outer hair cells and one row of inner hair cells. The function of outer hair cells are auditory amplifiers therefore they make all sounds entering the cochlea louder. The inner hair cells are then responsible for sending these amplified sounds via the nerve to the brain.
Hair cells within the cochlea become damaged due to exposure to loud noises, certain dis-eases and aging. The outer hair cells are always affected before the inner hair cells. Once the hair cells are damaged they die and cannot be regenerated. This is where the audiologist comes in.
If a patient has only outer hair cell damage (therefore sounds are not amplified) we can provide a hearing aid to amplify and make sounds louder. The hearing aid requires the inner hair cells to send these sounds to the brain. The hearing aid is therefore able to compensate for outer hair cell loss but not inner hair cell loss. Inner hair cells are the link to the brain so even with the hearing aid providing a high volume of amplification sounds cannot be heard without the inner hair cells sending that sound to the brain.
It is vital that a hearing impaired individual understand whether they have some degree of inner hair cell loss in order to have appropriate expectations from their hearing aids. Hearing aids cannot improve hearing to normal levels for everyone. Their effectiveness is determined by the severity of the hearing loss and most importantly if there is any degree of inner hair cell loss.
Patients with severe inner hair cell loss are able to hear loud sounds, however cannot hear speech even if it is very loud. This is because speech is a complex signal requiring functioning of most inner hair cells and when some or all are damaged it affects the patient’s ability to discriminate/hear speech. When an individual has a profound hearing loss they will need to make use of lip reading to assist in hearing and following conversations.
To find out more about hearing aids or to book a hearing test, contact Candice van Heerden Audiology on 011 615 3047.