Hearing tests Children

1. HEARING TESTS
IN CHILDREN
SCOTT BROWN’S LEARNING 2020
VOLUME 2 CHAPTER 9 – PG NO 65-74

2. ELECTROPHYSIOLOGICAL TESTING
• Otoacoustic emission (OAE), auditory brainstem response (ABR) and cortical
evoked response audiometry (CERA)
• Newborn screening and diagnostic testing of infants in the first 6 months
• Electrophysiological techniques are also used to confirm hearing thresholds

3. BEHAVIOURAL OBSERVATION AUDIOMETRY
• In behavioural observation audiometry (BOA), changes in activity are observed in
response to a sound stimulus.
• Response behaviours include eye widening, eye blink(auropalpebral reflex),
alteration in sucking response, arousal from sleep, startle or shudder of the body
or definite movement of the arms, legs or body.
• From 4–7 months, lateral inclination of the head towards the sound or a listening
attitude or stilling may be observed

4. CONT…
• The sound stimulus may be presented for <2 seconds, in a horizontal plane, 15 cm from
the child’s ear, out of peripheral vision, or delivered via insert earphones.
• The distractor observes evidence of a response
• Merit of allowing parents to participate in the assessment and witness their child’s
responses
• Verification of aided responses in infants, or in infants with a diagnosis of auditory
neuropathy spectrum disorder when ABR is a poor indicator of functional hearing levels
• Assessment of older children with learning disabilities who have not reached an
appropriate developmental stage for other means of assessment.

5. VISUAL REINFORCEMENT AUDIOMETRY
• Young children can be trained by operant conditioning to produce a localizing turn to a
visual stimulus in response to a sound stimulus
• The test room should be sound-treated to ensure low levels of ambient noise
• For soundfield testing, the loudspeakers should be placed at 90° from the child and at
the same height as the child’s head at a distance of at least 1 m from the ear.
• The duration of the signal is usually 2–3 seconds
• Visual reinforcers are generally placed adjacent to or above each speaker
• The reinforcer acts as a reward and therefore increasing the attractiveness or appeal to
the child and introducing variety is likely to sustain interest and reduce habituation.

6. CONT…
• First task must be to establish the conditioned response.
• A suprathreshold auditory signal should be presented concurrently with the visual reward
• The child may turn to locate the sound (orientation response) and thereby view the activated
reinforcer
• The sound stimulus should then be presented alone and the reinforcer only activated after
the child has produced an appropriate turning response.
• Once the child has demonstrated successful conditioning, the aim is to establish the minimal
response level (MRL) for each frequency
• The MRL is regarded as the quietest level at which two out of three clear responses were
recorded for each particular sound stimulus.

7. VRA DISTRACTION TEST

8. THE DISTRACTION TEST
• The test is based on the principle that the normal response observed when sound is
presented to an infant is a head turn to locate the source of sound
• In the classic distraction test described by McCormick, the item is covered by the
hands which maintain a fine attention control by moving the fingers slightly.
• The sound stimulus is presented by the second tester, half a second after the item is
covered.
• The sound stimulus should be presented in the horizontal plane to the ears at an
angle, set back 45° between 1 m and 15 cm from the child’s ear.
• The shorter distance increases the head shadow effect, thereby increasing the sound
stimulus on one side relative to the other

9. CONT…
• The normal response expected is a full head turn in the direction of the sound.
• This may be rewarded by a smile or vocal praise or gentle touch from the second
tester
• The intensity for soundfield testing is generally measured on the dB(A) scale
• Variable intervals between presentations and control ‘no sound’ trials are
essential for the validation of response thresholds in a distraction test

10. PITFALLS ENCOUNTERED IN BEHAVIOURAL OBSERVATION AUDIOMETRY,
VISUAL REINFORCEMENT AUDIOMETRY AND
DISTRACTION TESTING
Pitfalls Avoidance measures
Attempting conditioning to sub threshold stimuli Cautiously increase intensity of stimulus until a response
is elicited
Visual, tactile, olfactory clues from parent, distractor
or second tester
Critical observation of all parties
‘No sound’ control trials
‘Checking’ responses by child Critical assessment of responses
‘No sound’ trials, if necessary take a break, or sustain
distraction activity
Loss of interest in test, suprathreshold responses Vary the sound stimulus
Exchange roles of distractor or second tester
Use broader band or more interesting sounds
Inaccurate estimation of frequency and intensity of
stimulus
Use calibrated sound sources
Measure accurately with sound level meter, trying to
reproduce conditions
Extraneous noise, leading to false responses or only
suprathreshold response
Use a sound-treated room with ambient noise <30
dB(A)
Observe other auditory clues, e.g. clicking switch on
warbler

11. PERFORMANCE TESTING (PLAY AUDIOMETRY)
• It is based on the principle that the child is conditioned to wait for a sound and then to
respond with a play activity
• The conditioning sequence starts with the tester engaging the child’s attention by
holding the response item (e.g. the wooden man) poised waiting in front of the child
• A suprathreshold sound stimulus is presented and the tester responds by an
appropriate activity
• The child is then offered the response item and guided to wait and perform the task as
shown
• The interval between presentations must be randomly varied to avoid a predictable
rhythm. ‘No sound’ trials should be included.

12. PURE TONE AUDIOMETRY
• Key developmental age: 3 years onwards
• Insert earphones have the advantage of increasing transcranial attenuation
reducing ‘crossover’ and of reducing the effect of ear canal collapse which may
occur with supra-aural headphones
• The threshold is calculated by descending/ascending technique using 10/5 dB
steps

13. THE COOPERATIVE TEST
• Linguistic developmental level: 18–30 months
• Starting at a suprathreshold level, the voice is then dropped and visual clues
removed by covering the mouth.
• A child with normal hearing may discriminate the instruction at 35–40 dB(A).

14. SPEECH DISCRIMINATION TESTS
• In McCormick toy test, seven pairs of similar sounding nouns, each represented by a
small easily recognizable toy, placed on a table in front of the child in a quiet room,
i.e. a closed-set assessment.
• The word discrimination threshold (WDT) is taken as the quietest level at which the
child correctly identifies 80% of the toys including the paired consonants.
• For a child with normal hearing, this would be expected to occur at ≤40 dB(A).
• In Consonant Confusion Task (CCT) child is presented with nine sets of cards, each
showing four pictures representing monosyllabic words containing the same vowel
but different consonants such as cow/house/owl/mouse.

15. HEARING ASSESSMENT IN
CHILDREN WITH COMPLEX NEEDS
• Clear, simple demonstrations of conditioning tasks may require multiple
repetitions to achieve understanding
• Visually impaired children are more likely to respond to familiar sounds or if the
response is reinforced by a tactile reward such as puffs of air on the cheek.
• Pre-preparing the child by explanatory booklets or a personalized ‘social story’
may reduce the anxiety