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Resource Sheet
Understanding Hearing Impairment
A hearing loss may impact on students' ability to:
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produce speech sounds
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hear and understand language
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produce oral language
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acquire and use background knowledge across a range of topics
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access information presented in the classroom
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understand new concepts - particularly language-based concepts
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interact with other students.
The student may often be more comfortable in a small group or one-to-one situation. The
diagnosis will impact on each student differently at different stages. The student may have
additional difficulties in intellect or mobility, or may have a diagnosis in another impairment area.
A student with a hearing impairment will learn key concepts from the curriculum and develop the
skills to apply these. Some students with a hearing impairment may exceed year level
expectations in subject areas of interest, but then have fewer skills in other areas.
Degrees of hearing loss
The severity of a students hearing loss is measured in terms of how it impacts on their everyday life:
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Mild: 21-45 dB
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Moderate: 46-65 dB
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Severe: 66-90 dB
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Profound: 91 dB+
CEO Wollongong/MSPEC/ Understanding Hearing Impairment/V1.0/2652014
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Types of hearing loss
The general types of hearing loss can be described as congenital or acquired. A congenital hearing
loss is one that is present at, or soon after birth. An acquired hearing loss is one that occurs later
on in life. Depending on which part of the hearing system is affected, hearing loss is categorised
as conductive, sensorineural or a mixture of both
Conductive hearing loss
Conductive hearing loss is caused by blockage or damage in the outer ear, middle ear or both. It
leads to a loss of loudness. Some of the causes of a conductive hearing loss include ear infections,
perforated eardrum or blockage of the ear canal by wax or foreign objects. The degree of a
conductive hearing loss varies, but you cannot go completely deaf. A conductive hearing loss can
often be treated by medical or surgical means.
Sensorineural hearing loss
This is a result of damage to, or a malfunction of, the cochlea (the sensory part) or the hearing
nerve (the neural part). It results in a loss of loudness as well as a lack of clarity. Loss can be
caused by the ageing process, excessive noise exposure, diseases such as meningitis or Meniere’s
disease, and viruses such as mumps or measles. There is rarely any medical treatment for
sensorineural hearing loss, so it is permanent and hearing devices are often recommended.
Mixed hearing loss
A mixed hearing loss is caused by problems in both the conductive pathway (in the outer or
middle ear) and in the nerve pathway (the inner ear). An example of a mixed hearing loss is a
conductive loss due to a middle-ear infection combined with a sensorineural loss caused by
ageing.
Unilateral hearing (UL)
Only one ear is affected.
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Causes great difficulty in hearing in background noise.
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Makes localising the source of a sound very difficult (important for road safety)
Students with a unilateral hearing loss will have normal hearing in one ear and some degree of
hearing loss in the other ear. The worse hearing ear may have anything from a mild hearing loss
to profound. Usually the loss in the worse hearing ear is a ‘sensorineural loss’, which means it
cannot be cured or treated.
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Otitis Media (Conductive)
Otitis media is often referred to as ‘glue ear’, it describes fluid in the middle ear in the absence of
fever or inflammation of the drum. Minimal pain or discomfort seems to be experienced by the
students. The presence of the fluid may be transient, or may persist for many months.
Otitis media is particularly prevalent in childhood. It accounts for a large proportion of paediatric
presentations to health care professionals and is the most common cause of hearing loss in
children. Research shows 83% of children will have at least one episode of Acute Otitis Media by
the age of three. Otitis media is even more common among children who are Aboriginal, Torres
Strait Islanders or from a non-English speaking background, and in children with disabilities. Otitis
media is the general term referring to inflammation in the middle ear, which may include a range
of conditions.
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Acute otitis media (AOM)
... is diagnosed as an active infection of recent onset,
characterised by an inflamed ear drum and usually accompanied by pain and fever.
Discharge through a perforation of the tympanic membrane may occur. Hearing in the
affected ear is diminished.
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Recurrent otitis media (ROM) ... is characterised by three or more discrete episodes of
acute otitis media in a six-month period.
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Otitis media with effusion (OME).
Cochlear Implants
A cochlear implant is an electronic medical device that replaces the function of the damaged inner
ear. Unlike hearing aids, which make sounds louder, cochlear implants do the work of damaged
parts of the inner ear (cochlea) to provide sound signals to the brain. The cochlear implant enables
the sound to be transferred to the hearing nerves and enables the student to hear.
The process:
1. A sound processor worn behind the ear, or on the body, captures sound and turns it into
digital code. The sound processor has a battery that powers the entire system.
2. The sound processor transmits the digitally-coded sound through the coil on the outside of
the head to the implant.
3. The implant converts the digitally-coded sound into electrical impulses and sends them
along the electrode array placed in the cochlea (the inner ear).
4. The implant's electrodes stimulate the cochlea's hearing nerve, which then sends the
impulses to the brain where they are interpreted as sound.
CEO Wollongong/MSPEC/ Understanding Hearing Impairment/V1.0/2652014
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Central Auditory Processing Disorder (CAPD)
Central auditory processing disorder (CAPD) is said to affect about two percent of children.
Children with CAPD display a number of behaviours similar to the symptoms associated with
sensori-neural hearing loss. For example, they may complain that they find it difficult to hear when
the classroom is noisy. These behaviours may become apparent in the early school years, or at a
later stage of the child's life, due to changes in the acoustic environment, or to increased academic
demands.
Auditory Neuropathy Spectrum Disorder
Auditory Neuropathy Spectrum Disorder (ANSD) has previously been referred to in the literature
as Auditory Neuropathy (AN) and Auditory Dys-synchrony (AD). ANSD is a relatively complex type
of hearing loss that is believed to be due to abnormalities at the synapse of the inner hair cell and
auditory nerve, and/or the auditory nerve itself. ANSD can cause problems on two fronts:
1. Hearing levels: it can result in a hearing loss of any degree (mild, moderate, severe or
profound).
2. Speech discrimination: it can result in speech sounding very distorted. In some instances a
person with ANSD can have a relatively mild hearing loss demonstrated on an audiogram but
speech sounds so distorted to them that they experience severe problems when trying to
understand conversation on a day-to-day basis.
References:
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Australian Hearing www.hearing.com.au
Cochlear
http://www.cochlear.com/wps/wcm/connect/au/home/understand/hearing-andhl/hl-treatments/cochlear-implant/cochlear-implants
Queensland Government
http://education.qld.gov.au/staff/learning/diversity/diverse/swd.html#hi
National Acoustic Laboratories (NAL) http://www.nal.gov.au/hearingloss_tab_auditory.shtml
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