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Hearing Loss
The gradual hearing loss that occurs as you age (presbycusis) is a common
condition. An estimated one-third of Americans older than age 60 and one-half of
those older than age 85 have some degree of hearing loss.
Over time, the wear and tear on your ears from noise contributes to hearing loss by
damaging the cochlea, a part of your inner ear. Doctors believe that heredity and
chronic exposure to loud noises are the main factors that contribute to hearing loss.
Other factors, such as earwax blockage, can prevent your ears from conducting
sounds as well as they should.
You can't reverse hearing loss. However, you don't have to live in a world of quieter,
less distinct sounds. You and your doctor or hearing specialist (audiologist) can take
steps to improve what you hear.
Impairments in hearing can happen in either frequency or intensity, or both. Hearing
loss severity is based on how well a person can hear the frequencies or intensities
most often associated with speech. Severity can be described as mild, moderate,
severe, or profound. The term “deaf” is sometimes used to describe someone who
has an approximately 90 dB or greater hearing loss or who cannot use hearing to
process speech and language information, even with the use of hearing aids. The
term “hard of hearing” is sometimes used to describe people who have a less severe
hearing loss than deafness.
In the 2002–2003 school year, nearly 72,000 children ages 6 to 21 years got special
education services under the “hearing impairment” category in the United States.
Another 1,600 children received services under the “deaf blind" category. The total
number of children with hearing loss is likely higher, since some of them may have
other disabilities and be served under other special education categories. Still others
may not be counted because they receive only regular education services.
CDC tracks the number of children in a five-county area in metropolitan Atlanta,
Georgia who have moderate to profound hearing loss in both ears. For this project,
we define moderate to profound hearing loss as a 40 dB or greater loss in the better
ear, without the use of hearing aids. This activity is part of the Metropolitan Atlanta
Developmental Disabilities Surveillance Program (MADDSP). For 1991–1993, we
found that, on average, about 9 in every 10,000 children ages 3 to 10 years had a
moderate to profound hearing loss in both ears. Hearing loss was more common
among older children than among younger children. Ninety percent of the children
had a sensorineural hearing loss. Thirty percent of the children had one or more
other disabilities in addition to their hearing loss. [[Read a summary of the article
about hearing loss in MADDSP] [Read more about MADDSP]
CDC also studied hearing loss among children in metropolitan Atlanta in the mid1980s. This project was done as part of the Metropolitan Atlanta Developmental
Disabilities Study (MADDS), which studied how common certain disabilities were
among 10-year-old children. The study found that 11 of every 10,000 children 10
years of age were deaf or hard of hearing. Hearing loss was slightly more common
among boys than among girls. Twenty-eight percent of the children also had another
disability, such as mental retardation, cerebral palsy, or epilepsy. [Read a summary
of the article about hearing loss in MADDS] [Read more about MADDS]
In the 1988 National Health Interview Survey – Child Health Supplement, parents
reported that that 3.5% of children ages birth to 17 years in the United States had
ever had “deafness or trouble hearing” in one or both ears. [Read a summary of the
paper about hearing loss in children in 1988]
Hearing loss is more common among older people than among children. In the 1994
National Health Interview Survey Core and Second Supplement on Aging, one third
of adults ages 70 and older reported that they had trouble hearing. Seven percent
reported that they were deaf in both ears and another 8% reported that they were
deaf in one ear. Hearing loss was more common among men than among women.
[Read the report on adult hearing loss]
When describing hearing loss we generally look at three attributes: type of hearing
loss, degree of hearing loss, and the configuration of the hearing loss.
Hearing loss can be categorized by where or what part of the auditory system is
damaged. There are three basic types of hearing loss: conductive hearing loss,
sensorineural hearing loss and mixed hearing loss.
Conductive Hearing Loss
Conductive hearing loss occurs when sound is not conducted efficiently through the
outer ear canal to the eardrum and the tiny bones, or ossicles, of the middle
ear. Conductive hearing loss usually involves a reduction in sound level, or the ability
to hear faint sounds. This type of hearing loss can often be medically or surgically
corrected.
Examples of conditions that may cause a conductive hearing loss include:
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Conditions associated with middle ear pathology such as fluid in the middle
ear from colds, allergies (serous otitis media), poor eustachian tube function,
ear infection (otitis media), perforated eardrum, benign tumors
Impacted earwax (cerumen)
Infection in the ear canal (external otitis)
Presence of a foreign body
Absence or malformation of the outer ear, ear canal, or middle ear
Sensorineural Hearing Loss
Sensorineural hearing loss occurs when there is damage to the inner ear (cochlea) or
to the nerve pathways from the inner ear (retrocochlear) to the brain. Sensorineural
hearing loss cannot be medically or surgically corrected. It is a permanent loss.
Sensorineural hearing loss not only involves a reduction in sound level, or ability to
hear faint sounds, but also affects speech understanding, or ability to hear clearly.
Sensorineural hearing loss can be caused by diseases, birth injury, drugs that are
toxic to the auditory system, and genetic syndromes. Sensorineural hearing loss may
also occur as a result of noise exposure, viruses, head trauma, aging, and tumors.
Mixed Hearing Loss
Sometimes a conductive hearing loss occurs in combination with a sensorineural
hearing loss. In other words, there may be damage in the outer or middle ear and in
the inner ear (cochlea) or auditory nerve. When this occurs, the hearing loss is
referred to as a mixed hearing loss.
Degree of Hearing Loss
Degree of hearing loss refers to the severity of the loss. There are five broad
categories that are typically used. The numbers are representative of the patient's
thresholds, or the softest intensity that sound is perceived:
Normal range or no impairment = 0 dB to 20 dB
Mild loss = 20 dB to 40 dB
Moderate loss = 40 dB to 60 dB
Severe loss = 60 dB to 80 dB
Profound loss = 80 dB or more
Configuration of Hearing Loss
The configuration or shape of the hearing loss refers to the extent of hearing loss at
each frequency and the overall picture of hearing that is created. For example, a
hearing loss that only affects the high frequencies would be described as a highfrequency loss. Its configuration would show good hearing in the low frequencies and
poor hearing in the high frequencies. On the other hand, if only the low frequencies
are affected, the configuration would show poorer hearing for low tones and better
hearing for high tones. Some hearing loss configurations are flat, indicating the same
amount of hearing loss for low and high tones.
Other descriptors associated with hearing loss are:
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Bilateral versus unilateral. Bilateral hearing loss means both ears are affected.
Unilateral hearing loss means only one ear is affected.
Symmetrical versus asymmetrical. Symmetrical hearing loss means that the
degree and configuration of hearing loss are the same in each ear. An
asymmetrical hearing loss is one in which the degree and/or configuration of
the loss is different for each ear.
Progressive versus sudden hearing loss. Progressive hearing loss is a hearing
loss that becomes increasingly worse over time. A sudden hearing loss is one
that has an acute or rapid onset and therefore occurs quickly, requiring
immediate medical attention to determine its cause and treatment.
Fluctuating versus stable hearing loss. Some hearing losses change -sometimes getting better, sometimes getting worse. Fluctuating hearing loss
is typically a symptom of conductive hearing loss caused by ear infection and
middle ear fluid, but also presents in other conditions such as Meniere's
disease.
Eastern Shore ENT offers a complete range of services to evaluate hearing loss.