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Hearing loss can be caused by a range of factors. To discover the specific causes of hearing loss experienced by yourself or your loved ones, you should consult a licensed medical professional. Hearing loss can be either genetic, which means that it is inherited by a child from his or her parents, or environmental, which means that it is due to illness, injury, drug use, aging, or prolonged exposure to loud noise.

Certain types of hearing loss are not permanent and may be ameliorated if properly diagnosed and treated. Examples include earwax buildup, ear infection, swelling and inflammation, or the presence of a foreign object in the ear canal. Excess earwax or a foreign object can be removed by a specialist, while infections, swelling, and inflammation can be treated by a combination of topical applications and internal medications. In situations where physical damage to the ear is a distinct possibility, such as wrestling or boxing, specialized ear guards should be worn at all times to reduce the likelihood of damage to either the outer ear or the inner ear.

Certain illnesses affecting the ear can be treated if identified in time. Otosclerosis is a disease involving the middle ear that arises due to an issue affecting the stapes bone. In many cases, it can be treated through a surgical procedure known as a stapedectomy. Cholesteatoma is a disease in which a skin cyst grows into the middle ear. It too can often be treated surgically, by physically removing the cyst. Cancerous tumors affecting the ear, such as acoustic neuroma, can be treated through both surgical and therapeutic means.
Autoimmune diseases of the ear can have devastating effects, but can be treated if diagnosed in time.

Other types of hearing loss are progressive and permanent, such as presbycusis, which is hearing loss associated with aging, and Meniere’s syndrome, which is fluctuated hearing loss coupled with dizziness and tinnitus, or ringing in the ears. Blunt trauma or injury to the ear or to the head which impacts the eardrum, the inner ear, the middle ear, or the acoustic or auditory nerves can also cause hearing loss.

Certain drugs and chemicals are known to be toxic to proper ear function; these are referred to as “ototoxic” substances. A number of antibiotics, chemotherapy agents, loop diuretics, nonsteroidal anti-inflammatory drugs, and heavy metals are known to be ototoxic. Prolonged usage of such drugs or exposure to such substances can lead to permanent hearing loss.

Exposure to loud noise above 85 decibels can also have damaging effects on hearing. Known as noise-induced hearing loss (NIHL), it can occur in the work setting, such as jackhammers at a construction site or controlled explosions in a mine, or in a recreational setting, such as loudspeakers at a concert venue or earphones at home. For this reason, it is imperative that proper ear protection be used in any environment where exposure to loud noise is expected. Properly constructed and well fitting ear plugs and ear muffs can be effective and, in many instances, necessary safety devices to ensure that loud sounds are appropriately dampened before being allowed to penetrate into the ear canal.

Many people who are exposed to unsafe levels of noise are unaware of this fact and consequently do not take proper precautions. Individuals who work at factories, in industrial environments, or at manufacturing plants are commonly around machinery whose noise output can lead to ear damage over time unless proper protection is used. Individuals who work at music and performance venues or in night clubs are often exposed to amplified noise that can result in progressive hearing loss. Even individuals who work in quiet settings may underestimate the noise level associated with certain household activities such as running the lawn mower, riding a motorcycle, or operating certain power tools and appliances. In general, with any exposure to noise that is substantially louder than the sound of speech one should strongly consider the use of ear plugs or ear muffs.

Regardless of cause, hearing impairment is generally classified as either conductive, which means there is a problem with the outer ear, eardrum, or middle ear, or sensorineural, which means there is a problem with the inner ear, the auditory nerves, or the brain. Sensorineural hearing loss is the more common type. By conducting an examination and performing a series of tests, a licensed medical specialist can determine the appropriate classification.

For individuals with hearing impairment, the extent to which they are impaired will vary from person to person. The severity of an individual’s hearing loss is quantified by measuring the intensity of sound required for the individual to be able to hear that sound. The units of measurement are called “decibels of hearing loss” or “dB HL”, for short.

Hearing impairment in the 26 to 40 dB HL range is referred to as “mild”. Impairment in the 41 to 55 dB HL range is referred to as “moderate”. Impairment in the 56 to 70 dB HL range is referred to as “moderately severe”. Impairment in the 71 to 90 dB HL range is referred to as “severe”. Finally, impairment above 90 dB HL is referred to as “profound”.

Generally, hearing loss levels will vary depending on not only the volume, but also the frequency of a given sound. As a result, when measuring hearing impairment, a specialist will use an audiogram, which captures levels across the full applicable range of frequencies. To construct the audiogram, the specialist, most commonly an audiologist, conducts a hearing test during which a person is placed in a soundproof environment with a set of headphones that is able to transmit sounds to each ear independently. Each time the person detects a sound, he or she will signal to the audiologist by making a gesture or pressing a button. The audiologist then uses this information to construct the audiogram, plotting individual points identifying the frequency and volume of each sound heard by the person being tested.
For legal purposes, such as insurance claims and court proceedings, an individual’s level of hearing impairment measured in dB HL is converted to a percentage of hearing loss. Thus, it can be averred that an individual has “lost 50% of his hearing”, for example. The percentage measurement has limited usefulness outside of the legal setting, however.

Another detection methodology for hearing impairment is the speech-in-noise test, which measures an individual’s ability to pick up on speech in a noisy environment. Rather than focus on a person’s absolute ability to hear a sound, this test considers how well a person can separate certain types of sounds from other types of sounds. This is particularly helpful in detecting sensorineural hearing loss.

In cases where initial hearing tests warrant a more in-depth evaluation, the audiologist can perform additional assessments. A bone conduction hearing test, in which a tuning fork is placed behind and in front of the ear, is used to determine whether an individual’s hearing impairment is due to conductive or senorineural hearing loss. A tympanogram, in which the air pressure inside the ear canal is varied, is used to measure the performance of structures in the middle ear and to identify any fluid leakage. An acoustic reflex test, in which a probe is placed in the ear and a loud sound is produced, is used to measure the functioning of the stapedius muscle and provide information on the potential presence of a lesion.

In addition to hearing tests, a medical specialist can utilize a range of other diagnostic techniques in order to try and pinpoint the source of the hearing impairment. For example,   electronystagmography, posturography, and the Rotary Chair Test all provide information regarding the vestibular system, which is part of the inner ear. X-rays, CT scans, and MRI scans allow the specialist to receive internal images of the ear, enabling direct viewing of affected tissues. By utilizing these techniques, a specialist can get to the root of an individual’s hearing problem and determine whether the condition is treatable. In those cases where unimpaired hearing cannot be restored, a hearing aid may be a viable option.

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