SENSE OF HEARING
PATIENT, SAFETY, QUALITY & CARE BY AGA KHAN HOSPITAL, DAR ES SALAAM
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he outer ear is the part that is visible to us, all the way down the ear canal and up to the ear drum. The ear canal is where wax can build up – earwax is actually the body’s defence against dirt and other things that may enter the ear, and it also has antibacterial properties to keep our ears clean and healthy. Sometimes, however, it may become impacted and block off the ear canal, causing the feeling of a blocked ear and pain at times. It then needs to be removed by a professional (not with cotton buds!). Sounds go down the ear canal and hit the ear drum, which vibrates the bones in the middle ear. The three bones in the middle ear are the smallest bones in the body, and are responsible for detecting tiny movements of the ear drum and then passing on the vibrations into the inner ear. The middle ear also contains the eustachian tube, which connects to our nose and throat and ensures that the pressure in the middle ear is equalized with external pressure. However, because of this, sometimes when we get a cold or a throat infection we also experience pain and fullness in our ears. The inner ear has two portions; the cochlea (organ of hearing), and the balance organs. It is fluid-filled, and the cochlea consists of thousands of tiny hair cells that detect vibrations in the fluid that come from the middle ear. These hair cells then pass the sounds on to the brain via the cochlear nerve, creating nerve impulses in a way similar to the playing of a piano! Most sensorineural hearing losses are due to the loss of hair cells in the cochlea, caused by things like age, use of ototoxic medication, over-exposure to loud noises, etc. and are non-reversible.
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Dar Life I SEPTEMBER 2020
Ali Fayaz Jaffer
Clinical Audiologist
Hearing Loss For some people, the cause of hearing loss is the result of a gradual buildup of earwax, which blocks the ear canal and prevents conduction of sound waves. Earwax blockage is a cause of hearing loss among people of all ages. In most cases, however, hearing loss results from damage to the inner ear. Aging and prolonged exposure to loud noise may cause wear and tear on the hairs or nerve cells in the cochlea that send sound signals to the brain. When these hairs or nerve cells are damaged or missing, electrical signals aren’t transmitted as efficiently, and hearing loss occurs. Higher pitched tones may become muffled to you. It may become difficult for you to pick out words against background noise. Heredity may make you more prone to these changes. Ear infection and abnormal bone growths or tumors of the outer or middle ear can cause hearing loss. A ruptured eardrum also may result in loss of hearing. Getting Your Hearing Tested In adults and compliant children, hearing is typically tested using the pure-tone audiometry measurement. Audiometry is a completely painless, relatively quick test that determines your level of hearing. They work by recording your responses to certain sounds and pitches, and
For more information on Clinical Audiologist (Sense of Hearing), visit The Aga Khan Hospital or call us at +255 22 234 4625. All Picture Courtesy of The Aga Khan Hospital, Dar es Salaam
THE HUMAN EAR IS FAR MORE COMPLEX THAN IT LOOKS – OUR SENSE OF HEARING IS KNOWN TO BE THE MOST SENSITIVE OF OUR BODY’S SENSES. IT IS ALSO THE FIRST TO DEVELOP, AND BABIES BEGIN TO HEAR THEIR FIRST SOUNDS AT JUST 18 WEEKS OF PREGNANCY! judging your hearing based on these results. During an audiometry, you will be sat down and given a pair of stereo headphones. These go over your ears, and a series of short sounds will be played at various volumes and pitches. These sounds will be played in your left ear, right ear, and both ears. Then, your results are recorded on a graph – an audiogram. Both your left and right ear will be recorded separately, and their results can vary widely or match with one another. This graph will show how well you hear at certain volumes and frequencies.
