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LESSON 166

Play audiometry (CPA)

Year 2
Spring semester
Pediatric Audiology
Pediatric assessment
Duration: 11:31

This lesson covers conditioned play audiometry (CPA), used with preschool children. We explain the conditioning steps, choosing play and reinforcement, avoiding unintended cues, obtaining ear-specific and frequency-specific thresholds with earphones, frequency priority, an example result, and common challenges.

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Hello, and welcome to the AIHEAR Audiology Academy.
In this lesson we will learn conditioned play audiometry, or CPA, used with preschool children.
We will cover conditioning the child through play, obtaining ear-specific and frequency-specific thresholds, and keeping attention.
Conditioned play audiometry, or CPA, relies on the child making a play action when hearing a sound.
For example, on hearing the sound, the child drops a block into a bucket or puts a ring on a peg.
The method is based on conditioning: a link is built between the sound and the action.
A correct response is rewarded with reinforcement, such as praise, which makes it more likely to be repeated.
Under suitable conditions, CPA with earphones can give thresholds for each ear and each frequency.
In this respect, CPA is the behavioral method that brings a child's results closest to an adult audiogram.
Once again, what decides whether CPA is suitable is not chronological age but developmental age.
The method is usually used with children who are developmentally about two and a half to five years old.
The child needs to follow a simple instruction and to hold and release a small object such as a block.
The child is expected to focus on play, even briefly, and to learn to wait for the sound.
Some children can move to CPA around two years of age; others respond better to visual reinforcement audiometry for longer.
So switching between the two methods is done flexibly, according to the child's cooperation on the day.
Conditioning starts at a level at which the sound is clearly audible.
First, the tester or an assistant demonstrates the game by dropping a block into the bucket on hearing the sound.
Then the child's hand is held; when the sound comes, the block is dropped together and the child is praised.
After a few trials, help is reduced, and the child is expected to drop the block on their own on hearing the sound.
Conditioning is considered achieved when the child responds correctly without help on several consecutive trials.
After that, the level is lowered to search for the threshold.
In children with severe or profound loss, a higher level or vibration from a bone vibrator can be used for conditioning.
However, a response to vibration must not be mistaken for a hearing response during the threshold search.
The game should be a quiet, brief action that suits the child's age and interests.
Dropping a block into a bucket is the most common game and the easiest to teach.
Stacking rings or putting pegs in a board gives an orderly, calm response.
When the child starts to get bored, switching to a new game such as a puzzle piece or beads revives the responses.
In some systems, the response can also be obtained with a computer-based game in which a picture appears on screen.
It is important that the game makes no noise; a noisy toy can mask the test sounds.
In CPA, reinforcement is usually social praise, such as saying well done, smiling or clapping.
Keeping praise short and varied helps the child's interest last longer.
While presenting sounds, the tester should not look at the child or give unintended cues through facial expression or hand movement.
If sounds are presented in a regular rhythm, the child predicts the timing, so the intervals are varied.
If the child drops the block before the sound comes, the response is not rewarded and the child is gently shown to wait.
If such false responses are frequent, reliability is checked with control trials in which no sound is presented.
The greatest gain of CPA is that each ear can be tested separately with earphones.
Insert earphones are light and well tolerated by most children; supra-aural earphones can also be used.
Once the child has learned the game, the earphones can be put on as if they were part of the game.
If air-conduction thresholds are elevated, bone-conduction thresholds are also obtained with a bone vibrator.
Masking can be done with older, cooperative children, but masking noise can confuse a young child.
For a child who refuses earphones, testing starts in the sound field, but earphones are tried again for ear-specific information.
Because the child's attention span is limited, the most valuable information is collected first.
Usually one low and one high frequency are tested first in each ear, for example five hundred and two thousand hertz.
Then the same frequencies are obtained in the other ear, so even a short session gives information about both ears.
If time and attention allow, the remaining frequencies, such as one thousand and four thousand hertz, are added.
If air-conduction thresholds are elevated, bone-conduction thresholds are also obtained.
The order may vary with the clinic's protocol; what matters is getting useful information even if the session ends early.
In the threshold search, the adult rule is often used: down ten decibels after a response, up five decibels after no response.
To keep the child's interest, larger steps can be used at first, switching to smaller steps near threshold.
Threshold is taken as the lowest level at which the child responds consistently on repeated trials.
Sounds near threshold are hard to hear, so the child may stop responding; a louder reminder sound is given now and then.
In well-conditioned children, CPA thresholds can be close to those obtained with conventional audiometry.
A short note on the reliability of the result is added next to each threshold.
Now let us look at a purely example CPA result from a three-and-a-half-year-old child.
In this example, air-conduction thresholds in both ears are between thirty and forty decibels, that is, mildly elevated.
Bone-conduction thresholds are within normal limits, between five and ten decibels.
There is an air-bone gap of about twenty five decibels, which suggests a conductive hearing loss.
Tympanometry done on the same day gave flat, that is, type B, tracings in both ears.
These findings may be consistent with middle ear fluid; decisions on assessment and follow-up belong to the physician.
There are some challenges that are commonly met during CPA.
If the child gets bored with the game, responses drop; changing the game and keeping the session short helps.
Some children drop the block even when no sound comes; then waiting is taught again and control trials are used.
Shy children may find it hard to respond in an unfamiliar setting; a short warm-up game next to the parent builds trust.
The last responses from a tired child are less reliable, so the most important information is obtained at the start of the session.
If information is still missing, a second session scheduled soon after is often the best solution.
In children of CPA age, speech tests also complement the pure tone findings.
The speech recognition threshold can be found by having the child point to the picture of a familiar word or to a body part.
For a child who will not point to pictures, a speech detection threshold, or SDT, can be obtained.
The Ling sounds help quickly check access to low- and high-frequency speech sounds, especially in children who use devices.
Agreement between the speech threshold and the pure tone average is an important cross-check of the reliability of the results.
The report clearly states that the test was done with CPA and which type of earphone was used.
The child's cooperation and the reliability of each threshold, for example good or fair, are briefly noted.
Pure tone results are interpreted together with tympanometry and, if needed, otoacoustic emissions.
For example, a flat tympanogram is an independent finding that supports a mild conductive hearing loss.
Frequencies that could not be obtained are listed, and the next appointment is planned to complete them.
Results are explained to the family in terms of what the child may hear and miss in daily life.
A clinical tip: before starting CPA, plan what information you want to have when the session ends.
The child may stop cooperating unexpectedly, so first get one low and one high frequency in each ear.
Keep praise short, frequent and varied; change the game before the child gets bored.
Instead of reporting a low-reliability result as a firm finding, plan a retest soon after.
In CPA, the child is conditioned to make a play action, such as dropping a block into a bucket, on hearing the sound.
The method suits children who are developmentally about two and a half to five years old.
With earphones, thresholds can be obtained for each ear and frequency; bone conduction is added if needed.
Avoiding unintended cues, varying the intervals and planning the session are the basis of a reliable result.
Test yourself: in conditioned play audiometry, what is done to reduce responses made before the sound comes?
The correct answer is B: the intervals between sounds are kept irregular.
A movement made before the sound is not rewarded, and the child is gently shown that they need to wait.
In the next lesson we will learn speech perception tests for children, that is, open-set and closed-set tests.
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Prerequisites

LESSON 165 Visual reinforcement audiometry

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