What Can Cause Hearing Loss In Adults & Which Are The Tests to Diagnose It?

What Can Cause Hearing Loss in Adults?

Hearing loss in both adults and children may be the result of the damage to any portion of the peripheral and central auditory systems(1). Some of the degenerative processes associated with ageing, exposure to certain drugs comprising of ototoxic side effects, noise exposure, genetic mutations etc. are few of the main causes of sensorineural hearing loss in adults(1).

Age-Related Degenerative Processes(1)

The effect of ageing on the auditory system is one of the main causes of adult onset of hearing loss. Even when the sounds are loud, there is reduction in an individual’s ability to comprehend the speech. The hearing loss in older persons is caused by the cumulative effects of exposure to ototoxic drugs and noise. It is most pronounced at frequencies greater than or equal to 2000 Hz.

Noise Exposure Leading to Hearing Loss in Adults(1)

In this modern era, particularly people living in metropolitan cities are continuously exposed to factors that cause noise pollution. Noise exposure can occur in places like movie theatres, concerts, gymnasiums involving fitness workouts and by involving in certain activities like listening to loud music at home or some parties etc. In certain sections of military establishments and in some factories where there are high levels of exposure to loud noise can cause hearing loss in adults. The direct mechanical stress of loud sound pressure causes damage to sensory hair cells of the inner ear. Depending on the duration and intensity of exposure to noise, the hearing loss can be temporary or permanent.

Exposure to Therapeutic Drugs(1)

The drugs and chemicals also negatively affect the auditory system and cause damage to it. The main among them are antibiotics such as cisplatin and aminoglycoside. Both these drugs are very harmful to sensory hair cells and can be responsible for hearing loss in adults.

Genetic Mutations Causing Hearing Loss in Adults(1)

Hereditary hearing loss is predominantly common among newborns than adults, but in adults, it is difficult to estimate the heritability of onset hearing loss, since environmental and genetic and factors are not easily separable. The mutations in genes that are required for normal functioning of the cochlea cause hearing loss and most of these genes are responsible for affecting the sensory hair cells function.

Which Are the Tests To Diagnose Hearing Loss in Adults?

10 Important Tests to Diagnose Hearing Loss in Adults Include:

Physical Examination by a Doctor

The doctor will examine your ear for exploring possible causes of hearing loss, such as inflammation from an infection or presence of earwax(2). The doctor may also try to ascertain whether there are any structural causes of your hearing problems. The doctor will use an instrument called otoscope to examine the eardrum and the ear canal. Doctors may also look for piling up of earwax or any other substances, which may be hindering with the efficient performance of the ear and causing hearing loss in adults.

Whispered Voice Test for Hearing Loss in Adults(3, 4)

Whisper test is used by a doctor asking an individual to cover one ear with the other ear left uncovered, to check whether you are able to hear words that are spoken at different volumes and the manner in which you respond to other sounds, though its accuracy can be limited.

Tuning Fork Tests for Hearing Loss in Adults(4)

The doctor may also use a tuning fork, which is a slim “U” shaped metal instrument that vibrates in a specific frequency when struck produces a consistent sound to test the level of hearing and helps with the diagnosis of hearing loss in adults.

Audiometer Tests for Hearing Loss in Adults(4)

In this test, the audiologist makes the patient to use ear phones and make them hear words and sounds directed to each ear. Each of the tones is repeated at faint levels and the patient is asked to find the quietest sound that they can hear.

Tympanometry Test for Hearing Loss in Adults(4)

During the tympanometry test, the audiologist places a small device inside the ear canal. This device pushes air into the ear making the eardrum move back and forth. A machine records the movement on graphs termed tympanograms. This test helps in finding out if there is an underlying ear infection or if there are other problems, such as wax or fluid build-up; or a tear or hole in the eardrum.

Acoustic Reflex Measures for Hearing Loss in Adults(5)

They are called MEMR or middle ear muscle reflex, which tests how well the ears are responding to loud sounds. During the course of normal hearing, a minute muscle within the ear gets tightened when one hears loud noise(5). This phenomenon is known as the acoustic reflex and it occurs involuntarily. During the test, a soft rubber tip is placed within the ear by the audiologist and loud sound series are sent through the tips and recorded onto a machine, which indicates when the sound has triggered a reflex. If there is a hearing loss, then the sound may have to be very loud enough to trigger a reflex or it may not lead to any reflex at all.

Otoacoustic Emission Testing for Hearing Loss in Adults(4)

If the physical exam and medical history by a medical practitioner or audiologist indicates the cause of hearing loss to be sensorineural, then audiologists may think of performing otoacoustic emission testing to determine if the inner ear is damaged.

Audiologists conduct the test by placing a probe into the ear canal and then combination of sounds are introduced. If the functioning of cochlea is proper, the small hair cells lining it send back an echo when stimulated by sound. The probe detects this echo and determines if it is weak or absent, which may indicate hearing loss.

Auditory Brainstem Response Test (ABR)(4)

The ABR test is a specialized version of the electroencephalogram (EEG), where it calculates the electrical activity in the area of the brain, which receives the signals transmitted from the auditory nerve. Auditory Brainstem Response Test is also known as “brainstem-evoked response audiometry (BERA).”

Some clicking sounds are sent to the inner ears via headphones, which results in stimulation of the hair cells. This in turn produces electrical signals, which are transmitted to the brain via the auditory nerve and then measured. The ABR test is especially beneficial in diagnosis of hearing loss occurring as a result of auditory nerve damage.

CT Scans for Hearing Loss in Adults(6)

If conductive hearing loss is the outcome of the hearing tests conducted and which are causing the symptoms, then doctors may recommend a CT Scan to examine the middle ear in detail. CT scans uses electromagnetic radiation and creates a computerized three-dimensional image of the inner ear revealing damage to the bony components of the ear or an abnormal bone growth in the middle ear. This condition is called otosclerosis.

MRI Scans for Hearing Loss in Adults(6)

If the hearing loss affects only one ear and not other, then it is referred to as unilateral hearing loss. If the sensorineural hearing loss is the cause of the symptoms, the doctors may recommend an MRI scan to examine the inner ear and the structures surrounding it. MRI scans use magnetic fields and radio waves to create clear images of the interior components of the ear. An analysis of the scan may reveal a growth on the nerve pathway, such as acoustic neuroma, which prevent the ear from functioning in normal way resulting in hear loss.

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