A sensorineural hearing loss is due to insensitivity of the inner ear, the cochlea, or to impairment of function in the auditory nervous system. It can be mild, moderate, severe, or profound, to the point of total deafness. This is classified as a disability under the ADA and if unable to work is eligible for disability payments.The great majority of human sensorineural hearing loss is caused by abnormalities in the hair cells of the organ of Corti in the cochlea. There are also very unusual sensorineural hearing impairments that involve the VIIIth cranial nerve, the Vestibulocochlear nerve or the auditory portions of the brain. In the rarest of these sorts of hearing loss, only the auditory centers of the brain are affected. In this situation, central hearing loss, sounds may be heard at normal thresholds, but the quality of the sound perceived is so poor that speech can not be understood.Most sensory hearing loss is due to poor hair cell function. The hair cells may be abnormal at birth, or damaged during the lifetime of an individual. There are both external causes of damage, like noise trauma and infection, and intrinsic abnormalities, like deafness genes.Sensorineural hearing loss that results from abnormalities of the central auditory system in the brain is called Central Hearing Impairment. Since the auditory pathways cross back and forth on both sides of the brain, deafness from a central cause is unusual.
GJB2, is a human gene encoding for Gap junction protein, beta 2, 26kDa, or Connexin 26. Defects in this gene lead to the most common form of congenital deafness in developed countries, called DFNB1, also known as Connexin 26 deafness or GJB2-related deafness.
Ed 443 Auditory Impairment
Dr. Jacqui Cyrus
School of Education
Please take this short quiz at the beginning
of the presentation and again at the end.
– Explain definitions
– Know the historical contexts
– List and explain the major causes of hearing loss
– Discuss the concept of Deaf culture
– List the major assistive technologies specifically
designed for people with hearing impairments
– Highlight some support groups or organizations
– Cite some online resources
– Someone who is hard of hearing or who has
– Most would prefer to be called Deaf, Hard of
Hearing or deaf when the need arises to refer
to their hearing status, but not as a primary
way to identify them as people (where/when
their hearing status is not significant).
Definitions – cont’d
– In this uncapitalized form, the word quot;deafquot;
simply means unable to hear.
– Some deaf people also consider themselves
quot;Deafquot; with a capital quot;Dquot;, which does imply a
lot about their language and culture.
Deaf and deaf
– Many Deaf people (note the capital quot;Dquot;) may
prefer to be called Deaf instead of deaf, and are
quite happy being Deaf and use sign language as
a primary language
– Some deaf people, who were quot;born deafquot; have
rejected Deaf Culture and done everything
possible to survive in a quot;hearing worldquot; using
‘speech reading’ or other non-signing
• Pedro Ponce de Leon (1520-1584): first
teacher (Spanish monk) to teachdeaf
students to read, write and speak
• Thomas Hopkins Gallaudet studied in
England and France; started first special
school for the deaf in the U.S.
Historical Contexts – cont’d
• Gallaudet and Laurent Clerc (deaf and
well-known French educator of the deaf)
started the first American school for deaf
students in Hartford, CN.
– Hearing impairment that is so severe that the
child is impaired in processing linguistic
information through hearing, with or without
amplification, that adversely affects a child’s
• Hard of Hearing:
– Impairment in hearing, whether permanent or
fluctuating, that adversely affects a child’s
educational performance but that is not included
under the definition of deafness.
Types of Hearing Loss
• Conductive hearing loss occurs when sound
is not conducted properly through the outer
ear, middle ear, or both. It is generally a mild
to moderate impairment, because sound can
still be detected by the inner ear. More severe
impairments can occur, particularly in
Otosclerosis. Generally, with pure conductive
hearing loss, the quality of hearing (speech
discrimination) is good, as long as the sound
is amplified loud enough to be easily heard.
Conductive Hearing Loss
Conductive hearing loss has a variety of
– Ear canal obstruction
– Middle ear abnormalities:
– Tympanic membrane
Inner Ear Hearing Loss
Inner ear abnormalities:
– Superior canal dehiscence syndrome
– Otosclerosis: hardening of the stapes
Sensorineural Hearing Loss
A sensorineural hearing loss is due to
insensitivity of the inner ear, the cochlea,
or to impairment of function in the auditory
nervous system. It can be mild, moderate,
severe, or profound, to the point of total
Long-term exposure to environmental noise
Populations of people living near airports or
freeways are exposed to levels of noise
typically in the 65 to 75 dB(A) range. If
lifestyles include significant outdoor or open
window conditions, these exposures over time
can degrade hearing.
Genetic Hearing Loss
• Hearing loss can be inherited. Both dominant
genes and recessive genes exist which can
cause mild to profound impairment. If a family
has a dominant gene for deafness it will
persist across generations because it will
manifest itself in the offspring even if it is
inherited from only one parent. If a family had
genetic hearing impairment caused by a
recessive gene it will not always be apparent
as it will have to be passed onto offspring
from both parents.
– Deafness and hard of Hearing is a low
incidence disability for children affecting about
0.14% of all students
– 38% (60) students
Diseases or Illnesses
• Auditory nerve damage
– Measles may result in auditory nerve damage
– Meningitis may damage the auditory nerve or the
• Mumps may result in profound sensorineural
hearing loss(90 Decibel|dB or more), unilateral
(one ear) or bilateral (both ears).
• Adenoids that do not disappear by adolescence
may continue to grow and may obstruct the
Eustachian tube, causing conductive hearing
impairment and nasal infections that can spread to
the middle ear.
Diseases or Illnesses
• Chlamydia may cause hearing loss in
newborns to whom the disease has been
passed at birth.
• Premature birth results in sensorineural
hearing loss approximately 5% of the time.
• Syphilis is commonly transmitted from
pregnant women to their fetuses, and
about a third of the infected children will
eventually become deaf.
• Fetal alcohol syndrome is reported to
cause hearing loss in up to 64% of infants
born to alcoholic mothers, from the
ototoxic effect on the developing fetus plus
malnutrition during pregnancy from the
excess alcohol intake.
• AIDS and AIDS-related complex|ARC
patients frequently experience auditory
Behavioral Issues – cont’d
– Diuretics, aspirin, pain killers
• Physical trauma
– damage either to the ear itself or to the brain
– head injury
Quantification of Hearing Loss
– for adults: between 25 and 40 dB
– for children: between 20 and 40 dB
• Moderate: between 41 and 55 dB
• Moderately severe: between 56 and 70 dB
• Severe: between 71 and 90 dB
• Profound: 90 dB or greater
Age of Onset of Deafness
• The age at which the hearing impairment
develops is crucial to spoken language
acquisition. Post-lingual hearing
impairments are far more common than
• If the hearing loss occurs at a young age,
interference with the acquisition of spoken
language and social skills may occur.
• Share one resource that you think is great
for teachers learning about deafness.
• Question for further conversation:
– If other students with disabilities are also deaf,
should students who are ONLY separated be
– Waiting for the World to Change
• Teaching With Technology
– Pay Attention
• Mendiola, M. (2008)
• Manglona, F. (2008)