Description of how to to do audiological assessment in children

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Hearing Testing for Children
Dr CSN Vittal

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Principles of hearing
Bone Conduction
Air Conduction

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Units for measuring sound exposure
• Sound Pressure Level (SPL)
• expressed in μPa or Pa
• range from 20 μPa (hearing threshold) till 20 Pa (pain threshold)
• Decibel dB of sound pressure level (dB SPL)
• 20 log10 p1/p0 where
• p1 is actually measured sound pressure level of a given sound, and
• p0 is a reference value of 20μPa, which corresponds to the lowest
hearing threshold of the young, healthy ear.
• In the logarithmic scale the range of human ear’s audible sounds is from
0 dB SPL (hearing threshold) to 120-140 dB SPL (pain threshold)

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The examples of sound pressure levels in relation
to hearing threshold and pain threshold (in dB SPL)
Source / observing situation conversation
for a participant
Typical sound pressure level (db SPL)
Hearing threshold 0 dB
Leaves fluttering 20 dB
Whisper in an ear 30 dB
Normal speech 60 dB
Cars/vehicles for a close observer 60-100 dB
Airplane taking-off for a close observer 120 dB
Pain threshold 120-140 dB
Source: SCENIHR, (Scientific Committee on Emerging and Newly Identified Health Risks )
Health risks of exposure to no personal music players and phones including a music function (2008) , Section 3.3.3

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https://www.who.int/pbd/deafness/hearing_impairment_grades/en/

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Why hearing tests are important
• Soon after birth can help identify most babies with significant hearing
loss, and testing later in childhood can pick up any problems that have been
missed or have been slowly getting worse.
• It's important to identify hearing problems as early as possible because they
can affect your child's speech and language development, social skills and
education.
• An early diagnosis will also help ensure you and your child have access to
any special support services you may need.

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Hearing Loss
The American Academy of Ophthalmology and Otolaryngology (AAOO)
guidelines (Revised in 1979) states:
“The ability to understand normal everyday speech at a
distance of about 5 feet does not noticeably deteriorate as
long as the hearing loss does not exceed an average value of
25 dB at 500, 1000 and 2000 Hz”

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Prevalence Of Hearing Loss
• 1 to 3 per 1000 infants will have permanent
sensorineural hearing loss
• 1/1000 from the well baby nursery
• 10/1000 from the NICU
• Rate increases to 6/1000 by school age
Hearing Assessment in Infants and Children: Recommendations Beyond Neonatal Screening- Pediatrics 2003

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Types of Hearing Loss
• Conductive hearing loss is caused by
blockage in the transmission of sound
to the inner ear.
• Ear infections are the most common
cause of this type of hearing loss in
infants and young children.
• This loss is usually mild, temporary, and
treatable with medicine or surgery.

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Types of Hearing Loss ( Cochlear hearing loss)
• Sensorineural hearing loss can happen
when the sensitive cochlea has
damage or a structural problem
• The most common type, may involve a
specific part of the cochlea such as the
inner hair cells, outer hair cells, or both.

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Types of Hearing Loss
Mixed hearing loss happens when a
person has both conductive and
sensorineural hearing loss.
Central hearing loss occurs when the cochlea is working properly,
but other parts of the brain are not.
This rarer type of hearing loss is more difficult to treat.

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Why Is Early Identification Of Hearing Loss Important?
• A critical period exists for optimal language skills to
develop, and earlier intervention produces better
outcomes.
• Treatment of hearing defects has been shown to improve
communication.
• Children with hearing loss typically experience significant
delays in language development and academic
achievement.

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Signs of a hearing loss
• limited, poor, or no
speech
• frequently inattentive
• difficulty learning
• seems to need higher TV
volume
• fails to respond to
conversation level
speech
• Answers inappropriately
• fails to respond to his or
her name or
• easily frustrated when
there's a lot of
background noise

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High-risk Indicators For Hearing Loss In Children
From Birth To 24 mo of Age
• Family history of sensorineural hearing loss (SNHL), presumably congenital
• In utero infection associated with SNHL (eg, toxoplasmosis, rubella, cytomegalovirus, herpes,
syphilis)
• Ear and other craniofacial anomalies
• Hyperbilirubinemia at levels requiring exchange transfusion
• Birth weight less than 1500 g
• Bacterial meningitis
• Low Apgar scores: 0–3 at 5 min; 0–6 at 10 min
• Respiratory distress (eg, meconium aspiration)
• Prolonged mechanical ventilation for more than 10 d
• Ototoxic medication (eg, gentamicin) administered for more than 5d or used in combination with
loop diuretics
• Physical features or other stigmata associated with a syndrome known to include SNHL
(eg, Down syndrome, Waardenburg syndrome)

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Speech-Language-Auditory Milestones
• Birth to 3 mo. :
• Startles to loud noise
• Awakens to sounds
• Blinks or widens eyes in response to noises
• 3 to 6 mo:
• Quiets to mother’s voice
• Stops playing, listens to new sounds
• Looks for source of new sounds not in sight
• 6 to 9 mo:
• Enjoys musical toys
• Coos and gurgles with inflection
• Says ‘mama’
• 12 mo to 15 mo:
• Responds to his or her name and ‘no’
• Follows simple requests
• Uses expressive vocabulary of 3 to 5 words
• Imitates some words

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When to test Hearing ?
• Within a few weeks of birth – newborn hearing
screening and it's often carried out before discharge
from hospital after birth.
• From 9 months to 2.5 years of age – If any
concerns about child's hearing
• At around 4 or 5 years old – Most children will have
a hearing test when they start school

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Newborn Hearing Screening
• 1999 - The American Academy of Pediatrics
endorses: Universal newborn hearing screening.
• Detection of hearing loss before three months
of age.
• Intervention services initiated by six months of
age.
Language of early- and later-identified children with hearing loss. Yoshinaga Itano C, Pediatrics. 1998

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Newborn Hearing
Techniques
• Evoked otoacoustic emissions (EOAE).
• Auditory brainstem response (ABR).
• Auditory steady state response (ASSR) test

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Evoked Oto-Acoustic Emissions (EOAE)
• A test that uses a tiny, flexible plug that is
inserted into the baby's ear. Sounds are sent
through the plug.
• A microphone in the plug records the
otoacoustic emissions (responses) of the
normal ear in reaction to the sounds. There
are no emissions in a baby with hearing loss.
• This test is painless and is usually takes just
a few minutes, while the baby sleeps.
• Average test time is 5 minutes/baby

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Auditory Brainstem Response (ABR) or
Brain stem evoked response audiometry (BERA)
• A test that uses electrodes (wires)
attached with adhesive to the baby's
scalp. While the baby sleeps, clicking
sounds are made through tiny
earphones in the baby's ears.
• The test measures the brain's activity
in response to the sounds.
• As in EOAE, this test is painless and
test time around 30-45 min/baby

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Auditory Brainstem Response (ABR) or
Brain stem evoked response audiometry (BERA)
• The impulses are generated
by the brain stem.
• These impulses when
recorded contains a series of
peaks and troughs.
• The positive peaks (vortex
positive) are referred to by
the Roman numerals I - VII.
These peaks are considered to originate from:
1. Cochlear nerves - waves I and II
2. Cochlear nucleus - wave III
3. Superior olivary complex - wave IV
4. Nulclei of lateral lemniscus - wave V
5. Inferior colliculus - waves VI and VII

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Auditory steady state response (ASSR) test
• This test is similar to the ABR, though an infant usually needs to be sleeping or
sedated for the ASSR test.
• Sound passes into the ear canals, and a computer picks up the brain's response to t
he sound and automatically decides whether hearing loss is mild, moderate, severe,
or profound.
• This ASSR test has to be done with (and not instead of) ABR to check for hearing.

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Middle ear muscle reflex (MEMR)
• The MEMR (also called acoustic reflex test) tests how well
the ear responds to loud sounds by evoking a reflex.
• In a healthy ear, this reflex helps protect the ear against loud
sounds.
• For the MEMR, a soft rubber tip is placed in the ear canal.
• A series of loud sounds are sent through the tips into the ears
and a machine records whether the sound has
triggered a reflex.
• Sometimes the test is done while the child is sleeping.

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Hearing tests for the infant
The use of the above EOAE and ABR tests, PLUS
Behavioral audiometry
• Auditory signal presented to an infant
produces a change in behaviour e.g alerting,
cessation of an activity or widening of eyes.
• Moro`s reflex: sudden movement of limbs and
extension of head in response to sound of 80-
90 dB.
• Cochleo-palpebral reflex: Child responds by a
blink to aloud sound.
• Cessation reflex: Infant stops activity or starts
crying in response to a sound of 90 dB.

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Hearing tests for the
toddler
• To test hearing in children from
approximately 6 months to 2.5 years
old.
• Child is trained to look toward a sound
source. When the child gives a correct
response, the child is "rewarded"
through a visual reinforcement, such as
a toy that moves or a flashing light.
• Once this conditioned response is
reliably observed, the stimuli can be
presented at ever decreasing levels until
auditory threshold or minimum audible
levels have been reached.
Visual reinforcement audiometry

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Hearing tests for the toddler
For children between 1.5 and 5 years old
Sounds will be played through
headphones or speakers and your child
will be asked to perform a simple task
when they hear the sound. This may
vary from putting a ball in a bucket to
completing a puzzle or touch or move a
toy.
This test relies on the cooperation of the
child, which may not always be given.
Play audiometry
(Conditioned Play Audiometry)

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Hearing tests for the toddler
• Child is asked to repeat
the names of certain
objects or to point them
out on the pictures.
• Voice can be gradually
lowered.
• In this way hearing level
and speech discrimination
can be tested.
Speech audiometry

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Hearing tests for children older than 3 to 4 years
The above mentioned tests, along with the
following:
• Pure tone audiometry ("sweep
test”): used to screen a child's hearing
before they start school
• A machine generates sounds at
different volumes and frequencies.
• The sounds are played through
headphones and your child is asked to
respond when they hear them by
pressing a button.
• By changing the level of the sound, the
tester can work out the quietest
sounds your child can hear.

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Pure Tone Audiometry
• An audiometer is an electronic device which produces pure tones,
intensity of which can be increased or decreased in 5 dB steps.
• AC thresholds are measured for tones of 125,250,500,1K,2K,4K,8K Hz.
• BC thresholds are measured for tones of 250,500,1K,2K,4K Hz.
• It is charted in the form of a graph called audiogram.
• Handheld audiometers have a sensitivity of 92 percent and a specificity
of 94 percent in detecting sensorineural hearing impairment.

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Pure Tone Audiometry
Types
1. Screening audiometry - presents tones across the speech spectrum
(500 to 4,000 Hz) at the upper limits of normal hearing (25 to 30 dB for
adults, and 15 to 20 dB for children)
• Results are recorded as pass, indicating that the patient's hearing levels are within
normal limits, or refer, indicating that hearing loss is possible and a repeat screening
test or a threshold search test is recommended
2. Threshold search audiometry - determines the softest sound a patient
can hear at each frequency 50 percent of the time. (Modified Hughson-
Westlake method) - “Up 5-down 10" method of threshold estimation

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Nomenclature on the pure tone audiogram
O Right air conduction
X Left air conduction
[ Masked right bone
conduction
] Masked left bone
conduction

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Hearing tests for children older than 3 to 4 years
Immittance audiometry: an objective technique which evaluates
middle ear function by three procedures:
1. Static immittance,
2. Tympanometry, and
3. Acoustic reflex threshold sensitivity.
No single test should be considered a diagnostic 'end-all'. However, when
immittance test results are integrated with audiological data, they provide a
powerful adjunct to assist the physician in making a clinical diagnosis.

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1. Static Compliance
• Reciprocal of stiffness, is a measure of ear canal volume under two
specific physical conditions.
• In the first condition, (+) 200 mm H2O of positive air pressure is
applied to the ear canal and a volume (C1) is read. The second
volume reading (C2) occurs at a pressure value of maximum
eardrum compliance.
• Normally maximum eardrum compliance occurs when atmospheric
pressure is equal on both sides of the eardrum (0 mm H2O).

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2. Tympanometry (impedance audiometry)
• Tympanometry is a test to assess how flexible the eardrum is.
• It yields information about
1. the air pressure status of the middle ear.
2. the static acoustic immittance (establishing parameters of stiffness or flaccidity at the eardrum).
3. the integrity and mobility of the eardrum and ossicular chain.
4. the resonance point of the middle ear system.
A soft rubber tube will be placed at the
entrance of the child's ear. Air is gently
blown down the tube and a sound is
played through a small speaker inside it.
The tube then measures the sound that's
bounced back from the ear.

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Types of Tympanograms
A. negative pressure, indicative of a
malfunctioning eustachian tube;
B. positive pressure, usually associated
with initial symptoms of middle ear
effusion;
C. non-compliant, most associated with a
glue ear;
D. hypermobile/flaccid, indicative of either a
monomeric eardrum or ossicular chain
discontinuity;
E. vascular perturbations;
F. scarred eardrum resulting from repeated
perforations or trauma.

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3. Acoustic (Stapedial) reflex Measurements
• A loud sound, 70-100dB above the threshold of hearing of a particular ear causes
bilateral contraction of the stapedial muscle which can be detected by
Tympanometry.
• In a normal ear, void of middle ear pathology, the reflex occurs at approximately
80-90 dB HTL.
• Reflex arc is the VIIIth nerve, cochlear nucleus and complex brainstem internuclear
connections to the ipsilateral and contralateral facial nuclei, facial nerve and the
nerve to stapedius.
• Minimal auditory stimulus that produces a contraction of stapedius muscle is known
as acoustic reflex threshold and indicated on an audiogram by the letter ‘Z’.

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Physical volume of ear canal
• Acoustic immittance can measure the physical volume of
air between probe tip and TM.
• Normally it is up to 1ml in children and 2ml in adults.
• If > 2ml in children and > 2.5ml in adults, indicates
perforation of TM.

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Causes of hearing problems in babies and
children
• glue ear – a build-up of fluid in the middle ear, which is common
in young children
• Congenital infections such as rubella or cytomegalovirus
• inherited conditions, such as otosclerosis, which stop the ears or
nerves from working properly
• damage to the cochlear or auditory nerves (which transmit hearing
signals to the brain); this could be caused by a severe head injury,
exposure to loud noise or head surgery, for example
• being starved of oxygen at birth (birth asphyxia)
• illnesses such as meningitis and encephalitis

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Assessment of Hearing in Older Children and
Adolescents
• Initial Otoscopic Examination
• Speech Test
• Loud
• Whisper
• Tuning Fork Tests
• Weber
• Rinne
• Schwabach
• Audiometry
• Speech audiometry
• Pure tone audiometry
• Tympanometry
• BERA
• EChocG
• OAE (Otoacoustic
Emission)

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Initial Otoscopic
Examination
• Performed with a hand
held otoscope
• Ear canal and tympanic
membrane are observed.
• Tympanic membrane is
seen for:
• Light reflection
• Differentiation of its part
• Mobility

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Speech Test
• Simplest of all
• Involves testing ability to hear
words without using any
visual information.
• Patient should repeat 5 words
spoken loudly at a distance of
approx. 5 metre.
• The whispered voice test
involves the tester blocking
one of patients ears and
testing hearing by whispering
words at varying volumes.

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Tuning Fork Tests
• Used to differentiate between conductive and sensorineural
hearing loss.
PRINCIPLE:
• CHL (OE or ME Disorder)
• Sounds delivered to the ear via AC will be
attenuated
• If the sound is delivered to the ear via BC,
bypassing the OE & ME, then the sound
will be heard normally assuming there is no
disorder
• SNHL (OE & ME Are Free From Disorders)
• Sounds delivered to the ear via BC will also
be attenuated • Larger forks vibrate at slower frequency.
• Tuning forks with frequency 256 or 512 hz
are used

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Rinne Test & Weber Tests

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Schwabach’s Test
• Compares the patient's bone conduction to
that of the examiner's
• If the patient stops hearing before the
examiner, this suggests a sensorineural loss
• If the patient hears it longer than the
examiner, this suggests a conductive loss
• This test is dependent on the examiner having normal hearing.....