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The child is conditioned to wait for a frequency specific stimuli in the sound field and respond using a play activity
used from developmental age of 30 months [often as precursor to PTA since both use play technique]
Performance test
Should be quiet Should be free from distractions Should be comfortable Should be large enough to accommodate
parent, child, tester and equipment
Test room
VISUAL+AUDITORY RESPONSE REWARD
Initially hold and guide child’s hand◦ removes need for verbal feedback ◦ this guides response promptly◦ avoids premature response
Progress to gentle restraint
Conditioning
Within 6-12 attempts, the child should sit and wait with only occasional correction needed◦vary interval to ensure child is waiting
reliably◦correct any wrong response immediately◦make sure stimulus is supra-threshold
Reward with enthusiastic verbal and social praise
Proceed until child responds to the auditory signal alone
Conditioning
AUDITORY RESPONSE REWARD
Typical test sequence would be to gather minimum responses at high, low and mid frequencies [with stimuli all on one side]
Commence supra-threshold and decrease until minimum level with 2 out of 3 responses [aim to get to 25 dB HL]
Testing
“Go” and “sss” - 1m away and completely out of child’s vision
Hand held warblers (FMT)- out of the child’s vision and suitable distance away
Warble (FM) tones from a loudspeaker - 1m in front of child
Stimuli and placement
Balls on sticks Men in boat Pegs in board Stacking beakers Dropping bricks in box Knocking skittles off table** false responses should be correctable
Suitable activities
Measure voice levels on SLM and convert to dB(HL)
Measure levels on hand held warblers with SLM and convert to dB(HL)
Measure sound stimuli at the same distance that they were presented at
Calibration
◦Ensure you avoid visual cues◦Remember to reward◦Vary inter-stimulus interval◦Correct wrong response positively eg “let’s listen again” or “remember to
wait for the sound” Do not “tell the child off”, ◦Change ‘play’ activity to maintain
interest
Points to remember
◦Return to supra-threshold level if no response and when change frequency
◦Include localisation check at end of test◦Obtain minimal responses for 2-3
frequencies before attempting PTA◦Attempt to use 10 up 5 down procedure◦If conditioning not established after
about 15-20 presentations use VRA or distraction
Points to remember
Measured in dB(HL) Measures how many dB worse or better the
subject’s hearing is than normal human hearing
Results are recorded on an audiogram Air conduction is measured with
headphones Bone conduction is measured with the bone
vibrator Inserts may also be used
Pure Tone Audiometry
Audiometer and transducers must conform to standards
Audiometer should be calibrated at least every year
Carry out regular daily and weekly checks
Equipment
Wood S Chapter 6, in McCormick B [ed] Paediatric Audiology 0-5 years,. London: Whurr, 1993;155-186.
Key reading
Used from developmental age of 36 months Usually proceed to this after a successful
Performance Test Same set up as Performance Test but each
ear tested separately with audiometer placed directly behind child to avoid visual cues
Test room as for performance test ie quiet,comfortable, large no distractions
Pure Tone Audiometry with children
Condition as for Performance Test by demonstration and also with verbal instructions
If there is suspicion of a severe hearing loss conditioning can be done with the bone conductor
Procedure - conditioning
Frequencies 0.5-4 kHz Test 1KHz in each ear first Test 4KHz and 500Hz in each ear Test 2KHz in each ear Use 10 down 5 up procedure as for adults R/L [beware of asymmetry]
Frequency and levels tested
May use 20 down, 10 up May not need to go below 15-20 dB HL Need to vary inter-stimulus interval – may
need to include occasional supra-threshold stimuli
Choose the next threshold on the basis that it may be the last!!!
What if child has poor concentration?
Air conduction or bone conduction first?
If sound field results show some hearing loss do bone conduction first
Why?
If sound field results are within normal limits do air conduction first
Why?
If the child is clingy or anxious start with the performance test
The headphone can be detached from the band and held to the ear at first
Try using the bone conductor first Tester or parent or sibling can wear the
headphones first Don’t choose activities with a fiddly
response Don’t ask, tell!
Tips
Child should be able to do unmasked PTA Use different play activity for pure tone and
masking noise [possible from around age 4-5 yrs]
Avoid switching task too much Describe masking as rushing noise pure
tones as a whistle Select thresholds to be masked carefully –
may not be able to do all frequencies Beware of high levels of masking
Masking
3.5% Caused by pressure from transducer on
pinna Overcome problem by using insert ear
phones or place an admittance tip in the ear canal
Collapse of ear canal
Subject to more variation than a-c Limited output level Children with otitis media can show
depressed b-c thresholds at high frequencies, with subsequent improvement when the condition resolves
Bone conduction thresholds