While some cases of hearing loss are
reversible with medical treatment, many are
permanent.
Whether temporary or permanent, how
severely hearing is compromised is not
a uniform. In some cases the hearing
loss is only mild and or moderate and
individuals may not even be aware they
are affected. In other cases the degree
of deafness is profound and, although
vibrations will be sensed, even the
sound of a nearby jet engine will not
be heard.
Hearing loss can also differ in what
pitches (frequencies) are affected.
Human beings generally are sensitive to
even quiet sounds, as long as the
sounds are at certain pitches: ranging
from about 125 Hz to 8000 Hz. The
"human ear" is best tuned to pick up
sounds at the same pitches
(frequencies) as speech, from about 500
to 4000 Hz. The blast of a dog whistle
is not heard well even by people with
normal hearing because it makes a sound
that is at a very high frequency, above
the normal human range. Some people do
not hear well throughout this range,
but are "hard of hearing" depending on
the pitch of the sound (low frequency
hearing loss, high frequency hearing
loss, mid-frequency or U-shaped hearing
loss).
Hearing impairment comes from different
causes. Most commonly, the ear is
affected. Conductive hearing losses
involve clogging or abnormalities of
the outer or middle ear, and only
produce mild or moderate impairment, at
worst. Hearing loss due to
insensitivity of the inner ear, the
cochlea, can also be only mild or
moderate but can also be much more
severe, even causing complete
insensitivity to even the loudest
sounds (total deafness . Very unusual
hearing impairments involve the
auditory portions of the brain.
If the hearing loss occurs at a young
age, interference with the acquisition
of spoken language and social
development may occur. Hearing aids and
cochlear implants may alleviate some of
the problems caused by hearing
impairment, but are often insufficient.
People who have hearing impairments,
especially those who develop a hearing
problem later in life, often require
support and technical adaptations as
part of the rehabilitation process.