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Definition
Hearing impairment as a disability category is similar to the category of deafness, but it is not the same. The official definition of a hearing
impairment by the Individuals with Disabilities Education Act (IDEA) is
“an impairment in hearing, whether permanent or fluctuating, that
adversely affects a child’s educational performance but is not included
under the definition of ‘deafness.'” Thus, knowing the definition of deafness is
necessary to understand what sort of disabilities are considered
hearing impairments. A hearing loss above 90 decibels is generally
considered deafness, which means that a hearing loss below
90 decibels is classified as a hearing impairment.
Hearing
is one of the traditional five senses. It is the ability to perceive
sound by detecting vibrations via an organ such as the ear. The
inability to hear is called deafness. A hearing impairment or hearing
loss is a full or partial decrease in the ability to detect or
understand sounds. Caused by a wide range of biological and
environmental factors, loss of hearing can happen to any organism that
perceives sound.
Hearing loss can also be classified based on
which portions of the hearing system (auditory system) are affected.
When the nervous system is affected, it is referred to as sensorineural
hearing loss. When the portions of the ear that are responsible for
transmitting the sound to the nerves are affected, it is referred to as
conductive 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 deafness. This is classified as a disability under the ADA and if
unable to work is eligible for disability payments.
There are two main types of hearing loss.
- One happens when your inner ear or auditory nerve is damaged. This type is permanent.
- The other kind happens when sound waves cannot reach your inner ear due to ear wax build up, fluid or a punctured eardrum.
Hearing loss is categorized by its severity and by the age of onset.
Two persons with the same severity of hearing loss will
experience it quite differently if it occurs early or late in life.
Furthermore, a loss can occur on only one side (unilateral) or on both
(bilateral).
Hearing impairment may be ranked as mild, moderate, moderately severe, severe or profound:
- Mild:
for adults: between 26 and 40 dB HL
for children: between 20 and 40 dB HL
- Moderate: between 41 and 54 dB HL
- Moderately severe: between 55 and 70 dB HL
- Severe: between 71 and 90 dB HL
- Profound: 91 dB HL or greater
- Totally Deaf: Have no hearing at all.
Hearing loss can be inherited.
Both dominant gene 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. It is estimated
around half of all deafness and hearing impairment can be prevented.
People who are severely deaf rely a lot on lip-reading, even with a hearing aid.
Profoundly deaf people can also use sign language to communicate.
Hearing impaired persons with partial loss of hearing may find that the
quality of their hearing varies from day to day, or from one situation
to another or not at all. They may also, to a greater or lesser extent,
depend on both hearing-aids and lip-reading.
Any form of communication between people is a two way street. It
is very important then to determine how a deaf person prefers to
communicate. There are a number of options available to them such as
sign language, lip reading or using text. There will be a way of making a
connection. It may sometimes be difficult or awkward but the effort is
well worth it.
The commonest cause of hearing loss is ageing, and three-quarters
of people who are deaf are aged over 60. At around 20 years of age, our
hearing starts a gradual decline. Higher frequencies are usually the
first to go. This age-related hearing loss is normal and doesn't lead to
total loss of hearing. Age-related hearing loss (presbycusis) typically
begins with the loss of higher frequencies, so that certain speech
sounds - such as 's', 'f' and 't' - end up sounding very similar. This
means the older person can hear, but not always understand.
Many people who are deaf consider spoken language their primary
language and consider themselves "hard of hearing". How one classifies
themselves relative to hearing loss or deafness is a very personal
decision and reflects much more than just their ability to hear.
If your child has a hearing impairment, it
might mean there are challenges ahead. But with early intervention and
modern technology, children with a hearing impairment can be healthy,
happy and able to reach their full potential.
What is hearing impairment?
Hearing
impairment is when your child’s ears can’t do all the things they should
be able to do. For example, your child might have muffled hearing, or
she might not be able to hear sounds coming from some directions, or she
might have trouble hearing certain frequencies or sounds.
Types of hearing loss
There are two main types of hearing impairment – conductive and sensorineural.
Conductive hearing impairment is when sounds from
outside your child’s ear have trouble getting to or going through the
different parts inside the ear. Conductive hearing impairment is usually
temporary.
In
sensorineural hearing impairment,
the nerves that are in charge of receiving sound and sorting out what it
means don’t work properly. Sensorineural hearing impairment can be
mild, moderate, severe or profound.
Sensorineural hearing impairment usually lasts for life and can worsen over time.
Some children have only conductive hearing impairment. Others have sensorineural hearing impairment as well. This is called a
mixed hearing loss.
Universal newborn hearing screening
In Australia, universal newborn hearing screening is an essential part of diagnosing hearing impairment in children.
All Australian states and territories have a universal newborn hearing screening program that aims to:
- screen the hearing of all babies by one month of age
- refer any babies with possible hearing impairment for diagnostic testing with an audiologist by three months of age
- start early intervention for those babies with hearing loss by six months of age.
What is screening?
Screening equipment plays specific sounds into your baby’s ears and
records the responses from your baby. The screening technology might be
different in different parts of Australia.
In most places, your baby will be screened in hospital, before
you take your baby home. Each state has its own way of following up on
babies who don’t have a hearing screen in hospital.
Each state also has its own way of referring babies to audiology and supporting parents and families.
Hearing
screening isn’t compulsory. You have to give your permission for your
baby to be screened, which means signing a consent form.
If the screening test doesn’t pick up any hearing problems at birth, or
your child didn’t have his hearing screened as a newborn, but you’re
concerned about your child’s hearing, speech or language development,
ask your doctor to refer you to an audiologist to get your child’s
hearing tested.
Early diagnosis of hearing impairment means your
child can get early intervention and support. This can make a big
difference to her language development. If your child has undiagnosed
hearing impairment in early childhood, she could miss out on essential
learning and development opportunities.
Effects of Hearing Loss on Development
It is well recognized that hearing is critical to speech and language
development, communication, and learning. Children with listening
difficulties due to hearing loss or auditory processing problems
continue to be an underidentified and underserved population.
The earlier hearing loss occurs in a child's life, the more serious
the effects on the child's development. Similarly, the earlier the
problem is identified and intervention begun, the less serious the
ultimate impact.
There are four major ways in which hearing loss affects children:
- It causes delay in the development of receptive and expressive communication skills (speech and language).
- The language deficit causes learning problems that result in reduced academic achievement.
- Communication difficulties often lead to social isolation and poor self-concept.
- It may have an impact on vocational choices.
Specific Effects
Vocabulary
- Vocabulary develops more slowly in children who have hearing loss.
- Children with hearing loss learn concrete words like cat, jump, five, and red more easily than abstract words like before, after, equal to, and jealous. They also have difficulty with function words like the, an, are, and a.
- The gap between the vocabulary of children with normal hearing and
those with hearing loss widens with age. Children with hearing loss do
not catch up without intervention.
- Children with hearing loss have difficulty understanding words with multiple meanings. For example, the word bank can mean the edge of a stream or a place where we put money.
Sentence Structure
- Children with hearing loss comprehend and produce shorter and simpler sentences than children with normal hearing.
- Children with hearing loss often have difficulty understanding and
writing complex sentences, such as those with relative clauses ("The
teacher whom I have for math was sick today.") or passive voice ("The
ball was thrown by Mary.")
- Children with hearing loss often cannot hear word endings such as -s or -ed. This leads to misunderstandings and misuse of verb tense, pluralization, nonagreement of subject and verb, and possessives.
Speaking
- Children with hearing loss often cannot hear quiet speech sounds
such as "s," "sh," "f," "t," and "k" and therefore do not include them
in their speech. Thus, speech may be difficult to understand.
- Children with hearing loss may not hear their own voices when they
speak. They may speak too loudly or not loud enough. They may have a
speaking pitch that is too high. They may sound like they are mumbling
because of poor stress, poor inflection, or poor rate of speaking.
Academic Achievement
- Children with hearing loss have difficulty with all areas of academic achievement, especially reading and mathematical concepts.
- Children with mild to moderate hearing losses, on average, achieve
one to four grade levels lower than their peers with normal hearing,
unless appropriate management occurs.
- Children with severe to profound hearing loss usually achieve skills
no higher than the third- or fourth-grade level, unless appropriate
educational intervention occurs early.
- The gap in academic achievement between children with normal hearing
and those with hearing loss usually widens as they progress through
school.
- The level of achievement is related to parental involvement and the
quantity, quality, and timing of the support services children receive.
Social Functioning
- Children with severe to profound hearing losses often report feeling
isolated, without friends, and unhappy in school, particularly when
their socialization with other children with hearing loss is limited.
- These social problems appear to be more frequent in children with a
mild or moderate hearing losses than in those with a severe to profound
loss.
