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Hearing loss is a growing problem in the United States. Though it is still most common among the elderly, it is becoming increasingly prevalent among younger populations as well. Fortunately, this condition is often treatable with hearing aids, and some types of hearing loss are even preventable. Let’s take a look at the three main types of hearing loss, and the underlying causes of each.
Sensorineural hearing loss
By far the most common type of hearing loss, sensorineural hearing loss is a permanent loss that results from damage to either the tiny hair cells of the inner ear, or to the auditory nerve itself. This damage prevents or weakens the transfer of nerve signals to the brain, resulting in the inability to hear in certain frequencies. The nerve signals which are responsible for carrying information about sounds (such as loudness and clarity) to the brain become blocked.
-Noise-induced hearing loss
Repeated or prolonged exposure to loud noises or sounds, or a one-time exposure to a violently loud sound (such as an explosion) can result in permanent damage to the delicate structures of the inner ear. This type of hearing loss is extremely common, especially among young people. It is quite often preventable, if proper care is taken to protect the ears. Many people suffer hearing loss due to exposure to loud noises in the workplace, but noise-related hearing loss can also result from listening to music too loudly in one’s headphones, attending a loud concert without earplugs, or any number of other loud leisure activities. Many veterans also suffer from noise-related hearing loss, as well as tinnitus (a constant ringing in the ears) as a result of acoustic trauma.
-Normal deterioration caused by aging (presbycusis)
Hearing loss is a common disorder associated with aging, affecting between 30-35 percent of adults between the ages of 65-75. Most commonly, this type of hearing loss arises from normal changes in the ear as one ages, and often occurs in both ears. As hearing loss can be gradual, many people do not realize their hearing is diminishing until the loss becomes severe. Presbycusis often results in the inability to hear higher-pitched sounds, such as the chirping of a bird or the ringing of a telephone. Although age-related hearing loss is not preventable, it can be treated quite successfully with hearing aids or cochlear implants.
Other, less common causes of sensorineural hearing loss include: genetic syndromes, infections passed from mother to fetus inside the womb (such as toxoplasmosis or rubella), infections such as mumps and measles, certain medicines that are ototoxic (harmful to the ear), Meniere’s disease, damage caused by abrupt changes in air pressure, and many others.
Conductive hearing loss
Conductive hearing loss is less common than sensorineural, and occurs when there is an obstruction or damage to the outer or middle ear that prevents sound from being conducted to the inner ear. This type of hearing loss may be temporary or permanent, depending on the cause. It can often be resolved with medical treatment. Possible causes include:
-Malformation of outer ear, ear canal, or middle ear structures
-Fluid in the middle ear from colds
-Ear infection (an infection of the middle ear which interferes with the eardrum)
-Poor function of the Eustachian tube (a canal which controls the pressure in the middle ear)
-Infection in the ear canal
-Foreign object in the ear
-Otosclerosis (abnormal bone growth in the middle ear)
Mixed hearing loss
Mixed hearing loss is any combination of sensorineural and conductive hearing loss. Mixed hearing loss usually occurs when the ear has sustained some kind of trauma. This kind of hearing loss can also happen gradually over time, when one hearing loss is compounded by another. For example, an individual with a long-standing conductive hearing loss might experience presbycusis as they age. Alternatively, an individual with sensorineural hearing loss may find their symptoms temporarily more severe due to wax impaction.