Causes of Hearing Loss in Adults
While the worldly trend might be a decrease in the individuals risk of early hearing loss, the occurrence of hearing loss is likely to rise due to the ageing population worldwide. Another concern about the ageing process is cognitive decline, which may progress to mild cognitive impairment and eventually, dementia.
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Types and Causes of Hearing Loss
The relationship connecting hearing loss and cognitive decline has been studied in various research settings. There are several hypotheses about the underlying causal mechanism for age-related hearing loss and cognitive decline. One is this association can be explained by common aetiology or shared neurobiological pathology with a decrease in other physiological systems.
Another possible cognitive mechanism emphasises on an individual’s cognitive load. As people developing hearing loss in ageing, the cognitive load demanded by auditory perception increases, which may lead to a change in brain structure and eventually to dementia.
Loud noise is harmful to the inner ear. A one-time exposure to extreme sounds or listening to loud sounds over long periods can cause hearing loss. Loud noise can damage cells and membranes in the cochlea. Listening to loud noise for a long time can overwork hair cells in the ear, which can cause these cells to die. The hearing loss progresses if the noise continues. Injurious effects might continue even after noise exposure has stopped.
What Percentage of Hearing Loss Requires a Hearing Aid?
95% of Americans with hearing loss can be treated with hearing aids. Only around 5% of hearing loss in adults can be treated by surgery. Nine out of 10 hearing aid users report improvements in quality of life.
Sensorineural Hearing Loss (Also Called Nerve Deafness)
Noise-induced hearing loss typically manifests as elevated hearing thresholds (i.e. less sensitivity or muting). Various governmental, industry and standards organisations set noise standards. Many are unaware of the presence of environmental sound at damaging levels, or of the level at which sound becomes harmful.
Noise damage adds up; all likely sources for damage need to be looked at to assess risk. In the US, 12.5% of children aged 6–19yrs have permanent hearing damage from excessive noise exposure. The World Health Organisation (WHO) estimates that half of those between 12-35yrs are at risk with using personal audio devices too loud.
- Bones push the sound to the cochlea, a fluid-filled chamber in your inner ear.
- The cochlea is lined with tiny hairs that vibrate when the sound waves hit them.
- These hairs convert the sound waves into an electrical signal.
- That’s when your brain realises that a fire engine is headed toward you.
The most common causes can be a increase of wax in the ear canal, a perforated eardrum, also fluid in the middle ear, or damaged or defective middle ear bones. Everything from genetics and noise exposure to medications, head injuries and infections can play a role in hearing loss. Trouble detecting soft or high-pitched sounds are usually the first signs the stereocilia, the delicate hairs that change the sounds we hear into electrical signals within the ear, have been damaged.
Soft sounds including phone conversations or background noise in settings such as restaurants become difficult to hear. Ringing sounds in the ears, also called tinnitus, is another early signal of possible hearing loss. Central deafness is much less common than either presbycusis or conductive deafness. Central deafness is due to a problem with the hearing centres in the brain.
Most sounds can be heard, but conversation cannot be understood. Central deafness may follow a long illness with high fever, prolonged exposure to loud noise, head injuries, stroke, tumours, and certain medication.
Mixed Hearing Loss
People with both conductive and sensorineural symptoms are said to have mixed hearing loss. This can happen if there is a blockage or damage to the outer or middle ear and the cochlea or auditory nerve in the inner ear. Mixed hearing loss is caused by factors that contribute to conductive hearing loss and those that contribute to sensorineural hearing loss.
Any damage to the inner ear or the auditory neural system is generally permanent. In many severe cases, both the outer and inner hair cells don’t work correctly. This is a permanent hearing loss, and people usually benefit from cochlear implants.
In some other cases, the outer hair cells work correctly, but the inner hair cells or the nerve are damaged. This hearing loss is called auditory neuropathy spectrum disorder. The movement of sound from the inner ear to the brain is then disrupted.
Loud noise is often painful, so when someone raises their voice to be heard, it can seem as if they are shouting. When you have presbycusis, it can help if you ask others to speak slowly and clearly. Hearing loss is a universal setback that can happen at any age making verbal communication difficult. The ear is divided anatomically into three sections, and pathology contributing to hearing loss may strike one or more areas. Hearing loss can be categorised as conductive, sensorineural, or both.
What Is Normal Hearing?
Normal hearing is in fact a range of decibel levels from 0 dBHL (Decibel Hearing Level) — which is audiometric zero — to 20 dBHL. If a person’s hearing threshold is between 0 dBHL and 20 dBHL, the hearing is within normal limits. Hearing loss is identified as any threshold at any frequency over 20 dBHL.
Presbycusis is a steady decline in sound reception taking place as you get older. This happens because the eardrum loses some elasticity and the bones of the ear become stiffer. Men are usually more affected than women of the same age. Noise exposure throughout life may play a role in this hearing loss.
At first, you may have trouble understanding people with higher-pitched voices, including women and children. You may also have difficulty with conversations in groups or with background noise.
Risk Factors of Hearing Loss
Tinnitus might be heard in one or both ears, and it may be loud or soft. Tinnitus can frequently be the first sign of hearing loss in older adults. Tinnitus can accompany any hearing loss and may also be a sign of other health problems, such as high blood pressure, allergies, or as a side effect of medications. Besides damaging hair cells, noise can also damage the auditory nerve that carries information about sounds to your brain.
This can create a ‘hidden hearing loss’ that can make it more difficult to understand speech in noisy places. The effects of loud noises over time impact how well you might hear later in life. It also affects how quickly you might develop hearing problems, even after exposure has stopped.
Hearing loss in youngsters can be caused by a loud noise from toys, music by headphones, and concerts or events. Hearing loss is an ever increasing concern, especially in ageing populations, the occurrence of hearing loss increases around twice for each decade in age after age 40.
Can I Prevent Hearing Impairment?
Around one in four adults who reported excellent or good hearing had a similar pattern (5.5% on both sides and 18% on one side). Among people who reported exposure to loud noise at work, almost one third had such changes. This hearing loss happens when the delicate nerve fibres in the inner ear get damaged. It may be caused by excessive exposure to noise. Still, the most common causes of sensorineural hearing loss are the natural processes of ageing.
For some, the sensory cells wear out already at 50, whereas others have only negligible hearing loss even at 80. Tinnitus is characteristically described as ringing in the ears, but it also can sound like roaring, clicking, hissing, or buzzing.
Conductive Hearing Loss
Main reasons for conductive hearing loss include earwax impaction, otitis media, and otosclerosis. Reasons for sensorineural hearing loss include inherited disorders, noise exposure, and presbycusis. An understanding of the indications for medical management, surgical treatment, and amplification can help the family physician provide more effective care for these patients.
Findings on the association between hearing loss and dementia have significant public health implication since about 9% of dementia cases can be attributed to hearing loss. Conductive hearing loss is the result of problems with the outer or middle ear, which prevent sounds from getting through to the inner ear.