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Hearing Impairment
The term "Hearing Impaired" is a technically accurate description of someone who is hard of hearing or who has no hearing ... however, many Deaf, hard of hearing and late deafened people prefer not to be called impaired. They don't want to be primarily defined by their lack of (or poor) hearing.
Hearing
Impairment: Definitions, Assessment and Management
1.
Hearing Impairment
Hearing
Impairment: Definitions, Assessment and Management
Topics:
1.
Hearing Impairment
2.
Definitions
3.
Assessment
4.
Management
5.
Terms used by Action on Hearing Loss
6.
Anatomy and Physiology of the Ear
Parts of Human Ear:
Definitions:
Hearing loss is considered to be
the most prevalent congenital abnormality in newborns and is more than twice as
prevalent as other conditions that are screened for at birth, such as sickle
cell disease, hypothyroidism, phynilketonuria, and galactosaemia (Finitzo &
Crumley, 1999). It is one of the most common sensory disorders and is the
consequence of sensorineural and/or conductive malfunctions of the ear. The
impairment may occur during or shortly after birth (congenital or early onset
or may be late onset) caused post natal by genetically factors, trauma or
disease. Hearing loss may be pre-lingual (i.e., occurring prior to speech and
language acquisition) or post-lingual (i.e., occurring after the acquisition of
speech and language).
Since hearing loss in infants is
silent and hidden, great emphasis is placed on the importance of early
detection, reliable diagnosis, and timely intervention (Spivak et al., 2000). Even children who have
mild or unilateral permanent hearing loss may experience difficulties with
speech understanding, especially in a noisy environment, as well as problems
with educational and psycho-social development (Bess et al., 1988; Culbertson & Gilbert
1996). Children with hearing loss frequently experience speech-language
deficits and exhibit lower academic achievement and poorer social-emotional
development than their peers with normal hearing.
The period from birth to 3-5
years is often considered as the "critical period" for the
development of normal speech and language. Normal hearing in the first six
months of life is also considered critical for normal speech and language
skills. Hence, early identification and appropriate intervention within the
first six months of life have been demonstrated to prevent or reduce many of
the adverse consequences and to facilitate language acquisition
(Yowhinaga-Itano et al., 1998).
Consequently, in developed countries with a high standard of health care,
primary services include the early detection of congenital hearing loss and the
initiation of auditory habilitation before six months of age.
The prevalence of congenital and early-onset hearing loss in most
developed countries is estimated to range between 2-4 infants with
moderate-severe hearing loss in every 1000 births. In contrast, only limited
information is available on developing regions, including the Middle East
especially in the Arab countries, where the prevalence is estimated to be
markedly higher than in Israel or European and North American countries (Attias et al., 2006). In developing
countries, more than 10 infants in every 1000 births are estimated to be
affected by a severe
profound hearing loss. Of the 62
million deaf children younger than 15 years old worldwide, two-thirds reside in
developing countries (Smith, 2003).
Presbycusis (age-related hearing
loss) is the loss of hearing that gradually occurs in most individuals as they
grow older. Hearing loss is a common disorder associated with aging and is
ranked as the third most prevalent chronic condition in elderly people after
hypertension and arthritis. Its prevalence and severity increase with age,
rising from about 30-35 percent of adults aged 65 and older to an estimated
40-50 percent of adults aged 75 and older (Cruikshanks et al., 1998). The loss associated
with presbycusis is usually greater for high-pitched sounds. For example, it
may be difficult for someone to hear the nearby chirping of a bird or the
ringing of a telephone, and it is most difficult to understand speech in a
noisy background. However, the same person may be able to clearly hear the
low-pitched sound of a truck rumbling down the street. Presbycusis most often
occurs in both ears, affecting them equally. Because the process of loss is
gradual, people who have presbycusis may not realize that their hearing is
diminishing.
Schuknecht (1974) has described
four types of human presbycusis:
- sensory, mainly affecting the
cochlear hair cells and supporting cells
- neural, typified by the loss of
afferent neurons in the cochlea
- metabolic, where the lateral wall
and stria vascularis of the cochlea atrophy; and
- mechanical, where there seemed to
be a so-called "stiffening" of the basilar membrane and organ of
Corti
There are many causes of
presbycusis, though it is most commonly the result of changes in the inner ear
as a person ages. It can also stem from changes in the middle ear or from
complex changes along the nerve pathways leading to the brain.
The negative impact of hearing
loss on older adults is significant (LaForge et
al., 1992). Hearing loss is associated with depression, social isolation, poor
self-esteem, and functional disability (Mulrow et al., 1990a), particularly for those
suffering from hearing impairment who have not yet been evaluated or treated
for hearing loss.
Hearing impairment is a broad
term that refers to hearing losses of varying degrees, ranging from
hard-of-hearing to total deafness. As the general population continues to age,
the prevalence of hearing impairment can be expected to increase. Since the use
of hearing aids or surgical intervention to improve hearing loss has been shown
to have a positive impact on quality of life (Mulrow et al., 1990b, 1992; Weinstein, 1991),
more screening programs for elderly adults should be established, followed by
appropriate referral to audiologists based on individual needs. Without early
diagnosis and treatment of hearing impairment, quality of life and functional
status are likely to decline in the aging population.
The major challenge facing people with hearing impairment is
communication. Hearing-impaired persons vary widely in their communication
skills. Among the conditions that affect the development of communication
skills by persons with hearing impairments are personality, intelligence,
nature and degree of deafness, degree and type of residual hearing, degree of
benefit derived from amplification by hearing aid, family environment, and age
of onset. Age of onset
plays a crucial role in the
development of language. Persons with pre-lingual hearing loss (present at
birth or occurring before the acquisition of language and the development of
speech patterns) are more functionally disabled than those who lose some degree
of hearing after the acquisition of language and speech.
When describing hearing
impairment, three attributes are considered:
- Type of hearing loss (part of the
hearing mechanism that is affected).
- Degree of hearing loss (range and
volume of sounds that are not heard).
- Configuration (range of pitches or
frequencies at which the loss has occurred).
The prevalence of congenital and early-onset hearing loss in most
developed countries is estimated to range between 2-4 infants with
moderate-severe hearing loss in every 1000 births. In contrast, only limited
information is available on developing regions, including the Middle East
especially in the Arab countries, where the prevalence is estimated to be
markedly higher than in Israel or European and North American countries (Attias et al., 2006). In developing
countries, more than 10 infants in every 1000 births are estimated to be
affected by a severe
profound hearing loss. Of the 62
million deaf children younger than 15 years old worldwide, two-thirds reside in
developing countries (Smith, 2003).
Presbycusis (age-related hearing
loss) is the loss of hearing that gradually occurs in most individuals as they
grow older. Hearing loss is a common disorder associated with aging and is
ranked as the third most prevalent chronic condition in elderly people after
hypertension and arthritis. Its prevalence and severity increase with age,
rising from about 30-35 percent of adults aged 65 and older to an estimated
40-50 percent of adults aged 75 and older (Cruikshanks et al., 1998). The loss associated
with presbycusis is usually greater for high-pitched sounds. For example, it
may be difficult for someone to hear the nearby chirping of a bird or the
ringing of a telephone, and it is most difficult to understand speech in a
noisy background. However, the same person may be able to clearly hear the
low-pitched sound of a truck rumbling down the street. Presbycusis most often
occurs in both ears, affecting them equally. Because the process of loss is
gradual, people who have presbycusis may not realize that their hearing is
diminishing.
Schuknecht (1974) has described
four types of human presbycusis:
- sensory, mainly affecting the
cochlear hair cells and supporting cells
- neural, typified by the loss of
afferent neurons in the cochlea
- metabolic, where the lateral wall
and stria vascularis of the cochlea atrophy; and
- mechanical, where there seemed to
be a so-called "stiffening" of the basilar membrane and organ of
Corti
There are many causes of
presbycusis, though it is most commonly the result of changes in the inner ear
as a person ages. It can also stem from changes in the middle ear or from
complex changes along the nerve pathways leading to the brain.
The negative impact of hearing
loss on older adults is significant (LaForge et
al., 1992). Hearing loss is associated with depression, social isolation, poor
self-esteem, and functional disability (Mulrow et al., 1990a), particularly for those
suffering from hearing impairment who have not yet been evaluated or treated
for hearing loss.
Hearing impairment is a broad
term that refers to hearing losses of varying degrees, ranging from
hard-of-hearing to total deafness. As the general population continues to age,
the prevalence of hearing impairment can be expected to increase. Since the use
of hearing aids or surgical intervention to improve hearing loss has been shown
to have a positive impact on quality of life (Mulrow et al., 1990b, 1992; Weinstein, 1991),
more screening programs for elderly adults should be established, followed by
appropriate referral to audiologists based on individual needs. Without early
diagnosis and treatment of hearing impairment, quality of life and functional
status are likely to decline in the aging population.
The major challenge facing people with hearing impairment is
communication. Hearing-impaired persons vary widely in their communication
skills. Among the conditions that affect the development of communication
skills by persons with hearing impairments are personality, intelligence,
nature and degree of deafness, degree and type of residual hearing, degree of
benefit derived from amplification by hearing aid, family environment, and age
of onset. Age of onset
plays a crucial role in the
development of language. Persons with pre-lingual hearing loss (present at
birth or occurring before the acquisition of language and the development of
speech patterns) are more functionally disabled than those who lose some degree
of hearing after the acquisition of language and speech.
When describing hearing
impairment, three attributes are considered:
- Type of hearing loss (part of the
hearing mechanism that is affected).
- Degree of hearing loss (range and
volume of sounds that are not heard).
- Configuration (range of pitches or frequencies at which the loss has occurred).
Types of hearing loss
A hearing loss can be classified
as a conductive, sensory, neural, or mixed hearing loss, based on the anatomic
location of the problem (site of lesion, i.e.,
middle or inner ear). A hearing loss may also be labeled as unilateral or
bilateral, depending on whether the loss is in one (unilateral) or both
(bilateral) ears. The degree of loss might be the same in both ears
(symmetrical hearing loss) or it could be different for each ear (asymmetrical
hearing loss).
Conductive hearing loss :
Conductive hearing loss is characterized by an
obstruction to air conduction that prevents the proper transmission of sound
waves through the external auditory canal and/or the middle ear. It is marked
by an almost equal loss of all frequencies. The auricle (pinna), external
acoustic canal, tympanic membrane, or bones of the middle ear may be dysfunctional.
Conductive hearing loss may be congenital or caused by trauma, severe otitis
media, otosclerosis, neoplasms, or atresia of the ear canal. Some conductive
hearing loss can be treated surgically with tympanoplasty or stapedectomy, and
the use of hearing aids and assistive listening devices may also be beneficial.
Sensorineural hearing loss :
Sensorineural hearing loss occurs when the sensory receptors
of the inner ear are dysfunctional. Sensorineural deafness is a lack of sound
perception caused by a defect in the cochlea and/or the auditory division of
the vestibulocochlear nerve. This type of hearing loss is more common than
conductive hearing loss and is typically irreversible. It tends to be unevenly
distributed, with greater loss at higher frequencies. Sensorineural hearing
loss may result from congenital malformation of the inner ear, intense noise,
trauma, viral infections, ototoxic drugs (e.g., cisplatin, salicylates, loop
diuretics), fractures of the temporal bone, meningitis, ménière's disease,
cochlear otosclerosis, aging (i.e., presbycusis), or genetic predisposition,
either alone or in combination with environmental factors. Many patients with
sensorineural hearing loss can be habilitated or rehabilitated with the use of
hearing aids. Patients with profound bilateral sensorineural hearing loss
(e.g., at least 90 dB) who derive
no benefit from conventional hearing aids may be appropriate candidates for the
cochlear implant device, which bypasses the damaged structures of the cochlea
and stimulates the function of the auditory nerve. Auditory brainstem implants,
which are similar to multichannel cochlear implants, are used in patients with
neurofibromatosis type 2 following vestibular schwannoma removal, especially
those individuals who have lost integrity of the auditory nerves.
Auditory Neuropathy (AN):
Auditory Neuropathy (AN) is a
type of sensorineural hearing loss that can be congenital or acquired. Unlike
other types of sensorineural hearing loss where both Otoacoustic Emissions
(OAE) and Auditory Brainstem Response (ABR) tests are likely to be abnormal,
Auditory Neuropathy is characterized by normal OAE results
and significantly abnormal ABRresponses,
even when measured with very loud sounds. The combination of normal OAEresponses and severely impaired ABR responses
is thought to reflect normal outer hair cell (OHC) function in the cochlea and
abnormal auditory nerve function. The site of lesion forAN is often unknown, but possibilities
include cochlear inner hair cells, cochlear spiral ganglia, synapse and/or
eighth nerve fiber disorders. Audiograms of children with AN vary
from hearing in the normal range with complaints of difficulty hearing in
background noise to profound hearing loss.
mixed hearing loss:
Individuals with mixed hearing loss have both conductive and sensory
dysfunction. Mixed hearing loss is due to disorders that can affect the middle
and inner ear simultaneously, such as otosclerosis involving the ossicles and
the cochlea, head trauma, middle ear tumors, and some inner ear malformations.
Trauma resulting in temporal bone fractures may be associated with conductive,
sensorineural, and mixed hearing loss.
Auditory Processing Disorder
(APD):
Auditory Processing Disorder
(APD) is a deficit in neural processing of auditory stimuli that is not
due to higher order language, cognitive, or related factors. However, APD may
lead to or be associated with difficulties in higher order language, learning,
and communication functions. This type of auditory problem affects more complex
auditory processes, such as understanding speech when there is background
noise. The results of hearing sensitivity and physiological tests, such as
otoacoustic emissions (OAE) and auditory brainstem response (ABR) are normal in
children with a central auditory disorder.
A hearing loss can be classified
as a conductive, sensory, neural, or mixed hearing loss, based on the anatomic
location of the problem (site of lesion, i.e.,
middle or inner ear). A hearing loss may also be labeled as unilateral or
bilateral, depending on whether the loss is in one (unilateral) or both
(bilateral) ears. The degree of loss might be the same in both ears
(symmetrical hearing loss) or it could be different for each ear (asymmetrical
hearing loss).
Conductive hearing loss :
Conductive hearing loss is characterized by an
obstruction to air conduction that prevents the proper transmission of sound
waves through the external auditory canal and/or the middle ear. It is marked
by an almost equal loss of all frequencies. The auricle (pinna), external
acoustic canal, tympanic membrane, or bones of the middle ear may be dysfunctional.
Conductive hearing loss may be congenital or caused by trauma, severe otitis
media, otosclerosis, neoplasms, or atresia of the ear canal. Some conductive
hearing loss can be treated surgically with tympanoplasty or stapedectomy, and
the use of hearing aids and assistive listening devices may also be beneficial.
Sensorineural hearing loss :
Sensorineural hearing loss occurs when the sensory receptors
of the inner ear are dysfunctional. Sensorineural deafness is a lack of sound
perception caused by a defect in the cochlea and/or the auditory division of
the vestibulocochlear nerve. This type of hearing loss is more common than
conductive hearing loss and is typically irreversible. It tends to be unevenly
distributed, with greater loss at higher frequencies. Sensorineural hearing
loss may result from congenital malformation of the inner ear, intense noise,
trauma, viral infections, ototoxic drugs (e.g., cisplatin, salicylates, loop
diuretics), fractures of the temporal bone, meningitis, ménière's disease,
cochlear otosclerosis, aging (i.e., presbycusis), or genetic predisposition,
either alone or in combination with environmental factors. Many patients with
sensorineural hearing loss can be habilitated or rehabilitated with the use of
hearing aids. Patients with profound bilateral sensorineural hearing loss
(e.g., at least 90 dB) who derive
no benefit from conventional hearing aids may be appropriate candidates for the
cochlear implant device, which bypasses the damaged structures of the cochlea
and stimulates the function of the auditory nerve. Auditory brainstem implants,
which are similar to multichannel cochlear implants, are used in patients with
neurofibromatosis type 2 following vestibular schwannoma removal, especially
those individuals who have lost integrity of the auditory nerves.
Auditory Neuropathy (AN):
Auditory Neuropathy (AN) is a
type of sensorineural hearing loss that can be congenital or acquired. Unlike
other types of sensorineural hearing loss where both Otoacoustic Emissions
(OAE) and Auditory Brainstem Response (ABR) tests are likely to be abnormal,
Auditory Neuropathy is characterized by normal OAE results
and significantly abnormal ABRresponses,
even when measured with very loud sounds. The combination of normal OAEresponses and severely impaired ABR responses
is thought to reflect normal outer hair cell (OHC) function in the cochlea and
abnormal auditory nerve function. The site of lesion forAN is often unknown, but possibilities
include cochlear inner hair cells, cochlear spiral ganglia, synapse and/or
eighth nerve fiber disorders. Audiograms of children with AN vary
from hearing in the normal range with complaints of difficulty hearing in
background noise to profound hearing loss.
mixed hearing loss:
Individuals with mixed hearing loss have both conductive and sensory
dysfunction. Mixed hearing loss is due to disorders that can affect the middle
and inner ear simultaneously, such as otosclerosis involving the ossicles and
the cochlea, head trauma, middle ear tumors, and some inner ear malformations.
Trauma resulting in temporal bone fractures may be associated with conductive,
sensorineural, and mixed hearing loss.
Auditory Processing Disorder
(APD):
Auditory Processing Disorder
(APD) is a deficit in neural processing of auditory stimuli that is not
due to higher order language, cognitive, or related factors. However, APD may
lead to or be associated with difficulties in higher order language, learning,
and communication functions. This type of auditory problem affects more complex
auditory processes, such as understanding speech when there is background
noise. The results of hearing sensitivity and physiological tests, such as
otoacoustic emissions (OAE) and auditory brainstem response (ABR) are normal in
children with a central auditory disorder.
A great many, including what
exactly constitutes an APD, with
some professionals being still unconvinced that it exists as a separate
clinical entity, poor understanding of the boundaries and overlap between APD and
language or other developmental disorders, and lack of uniform accepted
guidelines regarding testing and management of APD.
Degree of hearing loss
- Deaf/Deafness refers
to a person who has a profound hearing loss and uses sign language.
- Hard of hearing refers
to a person with a hearing loss who relies on residual hearing to
communicate through speaking and lip-reading.
- Hearing impaired is
a general term used to describe any deviation from normal hearing, whether
permanent or fluctuating, and ranging from mild hearing loss to profound
deafness.
- Residual hearing refers
to the hearing that remains after a person has experienced a hearing loss.
It is suggested that greater the hearing loss, the lesser the residual
hearing.
·
The level of severity of
hearing loss, as used in this guideline, is defined as follows:
-10
to 15 dB HL
Normal
Hearing
16-25 dB
HL
Slight
Hearing Loss
26-40 dB
HL
Mild
Hearing Loss
41-55 dB
HL
Moderate
Hearing Loss
56-70 dB
HL
Moderate-Severe
Hearing Loss
71-90 dB
HL
Severe
Hearing Loss
>90 dB
HL
Profound
Hearing Loss
- Deaf/Deafness refers
to a person who has a profound hearing loss and uses sign language.
- Hard of hearing refers
to a person with a hearing loss who relies on residual hearing to
communicate through speaking and lip-reading.
- Hearing impaired is
a general term used to describe any deviation from normal hearing, whether
permanent or fluctuating, and ranging from mild hearing loss to profound
deafness.
- Residual hearing refers
to the hearing that remains after a person has experienced a hearing loss.
It is suggested that greater the hearing loss, the lesser the residual
hearing.
·
The level of severity of
hearing loss, as used in this guideline, is defined as follows:
-10
to 15 dB HL
|
Normal
Hearing
|
16-25 dB
HL
|
Slight
Hearing Loss
|
26-40 dB
HL
|
Mild
Hearing Loss
|
41-55 dB
HL
|
Moderate
Hearing Loss
|
56-70 dB
HL
|
Moderate-Severe
Hearing Loss
|
71-90 dB
HL
|
Severe
Hearing Loss
|
>90 dB
HL
|
Profound
Hearing Loss
|
Configuration of hearing loss
There are four general
configurations of hearing loss:
- Flat: thresholds essentially
equal across test frequencies.
- Sloping: lower (better) thresholds
in low-frequency regions and higher (poorer) thresholds in high-frequency
regions.
- Rising: higher (poorer) thresholds
in low-frequency regions and lower (better) thresholds in higher-frequency
regions.
- Trough-shaped ("cookie-bite"
or "U" shaped): greatest hearing loss in the mid-frequency
range, with lower (better) thresholds in low- and high-frequency regions.
There are four general
configurations of hearing loss:
- Flat: thresholds essentially
equal across test frequencies.
- Sloping: lower (better) thresholds
in low-frequency regions and higher (poorer) thresholds in high-frequency
regions.
- Rising: higher (poorer) thresholds
in low-frequency regions and lower (better) thresholds in higher-frequency
regions.
- Trough-shaped ("cookie-bite"
or "U" shaped): greatest hearing loss in the mid-frequency
range, with lower (better) thresholds in low- and high-frequency regions.
Assessment:
Hearing loss is confirmed using a
battery of audiologic tests, with the specific tests and measures selected
according to the age of the patient. However, in general, a comprehensive
hearing assessment designed to confirm hearing loss usually includes a hearing
history, physiological procedures, and behavioral procedures (see Table 1).
Hearing loss is confirmed using a
battery of audiologic tests, with the specific tests and measures selected
according to the age of the patient. However, in general, a comprehensive
hearing assessment designed to confirm hearing loss usually includes a hearing
history, physiological procedures, and behavioral procedures (see Table 1).
Table 1:
Components of a Comprehensive Hearing Assessment and Hearing
History
- General concern about hearing and
communication
- Auditory behaviors (reacting to and
recognizing sounds)
- History of otological diseases and
other risk factors for hearing loss
- General concern about hearing and
communication
- Auditory behaviors (reacting to and
recognizing sounds)
- History of otological diseases and
other risk factors for hearing loss
Physiological procedures or acoustic admittance measurements
Otoacoustic
emissions (OAE)
OAE are
low-level sounds produced by the sensory hair cells of the cochlea (primarily
the outer hair cells of the inner ear) as part of the normal hearing process.
Hair cells that are normally functioning emit acoustic energy, which can be
recorded by placing a small probe (containing a microphone) attached to a soft
ear tip in the external ear canal opening. The earphone delivers test signals
into the ear canal that evoke an acoustic response from the hair cells, and the
responses are recorded by a second microphone in the probe. These responses are
called evoked otoacoustic emissions (EOAE.
Auditory brainstem response (ABR)
Using clicks or tones, this test can
estimate hearing threshold sensitivity and determine the integrity of the
auditory pathway from the cochlea to the level of the brainstem. Small disc
electrodes are pasted on the scalp, and repetitive stimuli are delivered by an
earphone. The auditory potentials (electrical/neural activity generated by the
auditory nerve and brainstem) that are evoked by the repetitive stimuli are
then recorded by a computer.
Middle ear muscle reflexes
Involuntary middle-ear muscle reflexes to
sounds, usually elicited by moderately loud tones or noises, are recorded.
Tympanometry
This procedure is used to assess the
function of the middle ear by placing a small probe attached to a soft, plastic
ear tip at the ear canal opening and varying the air pressure released into the
ear canal. Tympanometry is not a hearing test.
Behavioral audiometry testing
The goal of behavioral audiometric testing
is to obtain a valid measure of hearing threshold sensitivity for each ear in
the speech-frequency range, ideally from 250 through 8,000 Hz. Results of the audiometric
assessment are displayed on an audiogram. Behavioral audiometric tests are used
to:
- Determine
whether or not a patient has a hearing loss.
- Determine
the degree, configuration, and type of hearing loss if hearing loss does
exist.
- Monitor
the patient's hearing over time.
- Provide
information for the fitting of hearing aids or other sensory devices.
- Help
determine the functional benefit of hearing aids or other sensory devices.
For children, behavioral audiometric test
methods are selected to be appropriate for the developmental age of the infant
or young child. The tests can be divided into two general categories:
unconditioned and conditioned behavioral response procedures.
Behavioral Observation Audiometry (BOA)
Behavioral Observation Audiometry (BOA) is an unconditioned behavioral response
procedure in which an observation of general awareness of sound (e.g., mother's
voice, environmental sounds and music) is used to determine a general level of
auditory responsiveness or function.
Visual Reinforcement Audiometry (VRA)
Visual Reinforcement Audiometry (VRA) is a conditioned behavioral response
procedure used to determine threshold sensitivity in infants beginning at
approximately six months of age (i.e., developmental age). A head-turn response
to the presentation of an audiometric test stimulus is rewarded by the
illumination and activation of an attractive animated toy.
Conditioned Play Audiometry (CPA)
Conditioned Play Audiometry (CPA) is a conditioned behavioral response
procedure used to determine threshold sensitivity in young children beginning
at approximately two years of age (i.e., developmental age). A play response
(block-drop, ring stack) to the presentation of an audiometric test stimulus is
rewarded, usually by giving the child social praise.
Speech Audiometry (SA)
Speech Audiometry is used to assess the ability to detect,
discriminate, identify, and comprehend speech. Several test procedures are used
for speech audiometry in infants and young children, including speech sounds
(syllables), words, phrases, and sentences. The tests can be conducted by using
earphones in each ear or through a loudspeaker. In infants, the conditioned
head-turn response can be used to estimate speech detection thresholds for words
or individual syllables. In young children, speech identification ability is
determined at a listening level that is comfortable for the child, well above
threshold. Usually, young children are asked to identify body parts (e.g.,
"Where's your nose?") or familiar objects (e.g., "ball,"
"spoon") by pointing to or picking up the object. Older children may
be asked to repeat the stimulus words or point to pictures in order to
determine their speech identification ability. The final speech identification
score (percent of words or simple sentences identified correctly) is sometimes
referred to as a "speech discrimination score" or "word
recognition score". The limitation of speech audiometry is that tests of
speech identification require that the stimulus items be within the child's
receptive vocabulary. Speech audiometry test results can be useful in
determining intervention goals, in monitoring auditory skill development, and
in examining the functional benefit of hearing aids or other assistive
technology.
Management:
Interventions for most infants and young
children with hearing loss are primarily focused on the following goals:
- Preventing
or reducing the communication problems that typically accompany early
hearing loss.
- Improving
the child's ability to hear.
- Facilitating
family support and confidence in parenting a child with a hearing loss.
Interventions focused on developing a
child's communication skills and abilities differ according to the type of
communication approach that will be used by the child and family. Communication
approach options for young children with hearing loss range from sign language
alone to auditory/verbal (spoken language) or various combination approaches.
Often parents must make an initial decision about a communication approach soon
after their child has been diagnosed with a hearing loss.
Parents also must choose a means for
improving their child's access to sound. The assistive devices most commonly
used to amplify sound are hearing aids. Other assistive devices include FM systems and tactile aids. Some children
with severe to profound hearing loss who have demonstrated little benefit from
conventional hearing aids may receive a cochlear implant, an electronic device
that is surgically placed in the inner ear.
An aural rehabilitation consultation is
considered medically necessary as part of the hearing impairment evaluation.
Aural rehabilitation is considered medically necessary for the treatment of a
hearing impairment when ALL of the following criteria are met:
- The
hearing impairment is the result of trauma, tumor, or disease or following
implantation of a cochlear or auditory brainstem device.
- An
evaluation that includes standardized speech and/or hearing tests has been
completed by a certified speech-language pathologist or licensed
audiologist.
- The
treatment being recommended has the support of the treating physician.
- The
therapy being ordered requires one-to-one intervention and supervision by
a speech-language pathologist or audiologist.
- The
therapy plan includes specific tests and measures that will be used to
document significant progress.
- Meaningful
improvement is expected from the therapy.
- The
treatment includes a discharge plan for the transition from one-to-one
supervision to maintenance provided by an individual or caregiver.
Aural rehabilitation refers to the
services and procedures needed to facilitate adequate receptive and expressive
communication in individuals with hearing impairments [American
Speech-Language-Hearing Association (ASHA), 1984]. It is also called auditory
or audiologic rehabilitation. Aural rehabilitation is typically an integral
component used in the overall management of individuals with hearing loss and
is often an interdisciplinary endeavor involving physicians, audiologists, and
speech-language pathologists. For school-age children, therapy may also be
coordinated with the school system. In general, services may be initiated as
soon as a patient has been identified as having a hearing impairment or
following the fitting of a hearing device or implantation of a cochlear device.
Services
involved in the provision of aural rehabilitation include
- Identification
and evaluation of sensory capabilities, including the extent of impairment
and the fitting of auditory aids.
- Interpretation
of the audiological findings, plus counseling and referral.
- Development
and provision of an intervention program for communicative disorders in
order to facilitate expressive and receptive communication.
- Re-evaluation
of the patient's status.
- Evaluation
and modification of the intervention program.
Aural rehabilitation should be structured,
systematic, individualized, and goal-directed (i.e., both long- and short-term
goals). Although aural rehabilitation programs are accepted and widely used in
the management of hearing-impaired individuals, the role of aural
rehabilitation in overall treatment and its impact on health outcomes has not
been clearly delineated, other than for patients with cochlear device implants.
For patients who acquire a hearing loss post-lingually, treatment would be
considered rehabilitative and restorative in nature. Although the term
"rehabilitation" is commonly used in association with services
provided to pre-lingually hearing-impaired patients, treatment would more
accurately be described as "habilitation" in nature, as it does not
involve restoring a lost function.
Audiologists and speech-language
pathologists certified by ASHA (2006) are qualified to provide aural rehabilitation components.
The audiologist is typically responsible for the fitting, dispensing, and
management of a hearing device, for providing counseling about hearing loss and
ways to enhance communication skills, and for providing training on
environmental modifications that will facilitate the development of receptive
and expressive communication. The speech-language pathologist is typically
responsible for evaluating receptive and expressive communication skills and
for providing services to improve them, as well as for providing training and
treatment in communication strategies (e.g., assertive listening tactics),
speech-perception training (e.g., speech-reading, auditory training, and
auditory-visual-speech-perception training), speech and voice production, and
comprehension of oral, written, and sign language.
Initially, aural rehabilitation records
should be provided to substantiate the need for this therapy. Records should
include clinical narrative notes from the attending physician or referring
provider, with a description of expressive and/or receptive speech impairments
and reports of standardized speech and hearing tests, if applicable. An
evaluation and treatment plan, including assessment of function level,
measurable long- and short-term goals, progress toward achieving goals,
anticipated timeframe for achieving goals, and anticipated frequency and
duration of therapy, should also be provided. For continued treatment, it is
necessary to obtain follow-up evaluations, auditory therapy notes,
documentation of progress toward goals, and treatment plan revisions.
Both group therapy and computer-based
training are often used in aural rehabilitation; however, these methods are not
individualized to specific patient needs. The primary focus of many aural
rehabilitation components and interventions may be training (e.g., speech-reading
training, vocational training), held in either group or individual sessions.
Group-based therapy, computer-based learning programs, and school-based
programs are considered as training in nature and not medically necessary, as
they do not involve the formal interaction of one-to-one supervision with a
speech-language pathologist or audiologist and are not tailored to meet
individual needs. Furthermore, maintenance programs of routine, repetitive
drills and exercises that do not require the skills of a speech-language
therapist or audiologist and that can be reinforced by the individual or
caregiver are also considered to be outside the realm of medical prescription.
Aural
rehabilitation following cochlear device and auditory brainstem implantation
Aural rehabilitation following
implantation of cochlear and auditory brainstem devices is considered an
integral part of the overall management of implant patients. Although programs
vary widely, both with regard to treating disciplines and to the duration and scope
of treatment, the general consensus is that some type of post-implantation
aural therapy maximizes the benefit of the device. Sound recognition and speech
intelligibility are evaluated prior to and just after implantation. Hearing
capabilities are assessed by an audiologist, both with and without the
assistance of a hearing aid. A speech-language pathologist evaluates and
categorizes the patient's pre-implantation speech and language skills.
Post-cochlear implantation rehabilitation programs generally include the
following components: sound awareness (e.g., recognition of novel auditory
signals); visual/auditory processing, including speech-reading training (e.g.,
lip-reading, facial expression, gestures, and body language); speech
recognition; mechanical training (e.g., use of the device and telephone); and
voice, speech production, and language therapy.
Terms used by Action on Hearing
Loss
These are some of the
terms we use to describe deafness...
People who are deaf
We use the term people who are deaf in a
general way when we are talking about people with all degrees of hearing loss.
People who are hard of hearing
We use the term hard of hearing to
describe people with mild to severe hearing loss. We quite often use it to
describe people who have lost their hearing gradually.
People who are deafened
People who were born hearing and became
severely or profoundly deaf after learning to speak are often described as
deafened. This can happen either suddenly or gradually.
People who are deafblind
Many people who are deafblind have some
hearing and vision. Others will be totally deaf and totally blind.
The Deaf community
Many deaf people whose first or preferred
language is British Sign Language (BSL) consider themselves part of the Deaf
community. They may describe themselves as Deaf with a capital D to emphasise
their Deaf identity.
Definitions of deafness
Your level of deafness – mild, moderate,
severe or profound – is defined according to the quietest sound, measured in
decibels, that you can hear.
Anatomy
and Physiology of the Ear
What
is the ear?
The
ear is the organ of hearing. The parts of the ear 3 three include:
·
External
or outer ear, consisting of:
o
Pinna
or auricle. This is the
outside part of the ear.
o
External
auditory canal or tube. This is the tube that connects the outer ear
to the inside or middle ear.
·
Tympanic
membrane (also
called the eardrum). The tympanic membrane divides the external
ear from the middle ear.
·
Middle
ear (tympanic
cavity), consisting of:
o
Ossicles. Three small bones that are connected and
transmit the sound waves to the inner ear. The bones are called:
§ Malleus
o
Eustachian
tube. A canal that
links the middle ear with the throat area. The eustachian tube helps to
equalize the pressure between the outer ear and the middle ear. Having the same
pressure allows for the proper transfer of sound waves. The eustachian tube is
lined with mucous, just like the inside of the nose and throat.
·
Inner
ear, consisting of:
o
Cochlea (contains the nerves for hearing)
s
s
How
do we hear?
Hearing
starts with the outer ear. When a sound is made outside the outer ear, the
sound waves, or vibrations, travel down the external auditory canal and strike
the eardrum (tympanic membrane). The eardrum vibrates. The vibrations are then
passed to three tiny bones in the middle ear called the ossicles. The ossicles
amplify the sound and send the sound waves to the inner ear and into the
fluid-filled hearing organ (cochlea).
Once
the sound waves reach the inner ear, they are converted into electrical
impulses, which the auditory nerve sends to the brain. The brain then
translates these electrical impulses as sound.
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