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LESSON 163

Introduction to pediatric audiology

Year 2
Spring semester
Pediatric Audiology
Pediatric assessment
Duration: 9:46

This lesson introduces the core principles of pediatric audiology. We cover the acoustic differences of a child's ear, choosing tests by developmental and corrected age, family-centered care, the pediatric case history, and the cross-check principle.

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Hello, and welcome to the AIHEAR Audiology Academy.
With this lesson we begin the pediatric assessment section and learn the core principles of assessing a child's hearing.
We will cover choosing tests by developmental age, the family-centered approach and the cross-check principle.
There is a well-known saying in pediatric audiology: a child is not a small adult.
A child's ear is not only small but also acoustically different, and this difference directly affects measurements.
A child's response to sound changes with developmental level, from a startle to a head turn, then to play and a spoken reply.
Attention span is short, so the information that can be obtained in one session is limited and the test order is planned in advance.
Most importantly, a hearing loss that goes unnoticed in this period can affect speech and language development.
So the goal of pediatric assessment is to obtain reliable information for each ear as quickly as possible.
Now let us look at how these differences affect measurements and test choice.
A baby's ear canal is shorter and narrower than an adult's, and its volume is much smaller.
The same audiometer setting produces a higher sound pressure in a small ear canal than in an adult's.
This difference is taken into account, especially in hearing aid fitting, by measuring the real-ear-to-coupler difference.
In the first months of life the ear canal wall is softer, so one thousand hertz probe tone tympanometry is used in babies under six months.
In the preschool years, middle ear fluid is common and can cause temporary conductive hearing loss.
So at every assessment of a child, middle ear status is also examined separately.
What decides the test choice is not the child's chronological age but the developmental age.
In babies developmentally younger than six months, behavioral observation is possible, but thresholds are estimated with objective tests.
From about six to twenty four months, visual reinforcement audiometry, or VRA, is used.
From about two and a half to five years, the child is conditioned to respond through play; this is conditioned play audiometry, or CPA.
From around five years, most children can be tested with conventional audiometry, by pressing a button or raising a hand.
These limits are not fixed; for a child whose development is advanced or delayed, the method is chosen to suit the child.
Objective tests, such as tympanometry, otoacoustic emissions, or OAE, and the auditory brainstem response, or ABR, suit any age.
In babies born prematurely, development is assessed according to corrected age.
Let us take a purely example baby whose chronological age is nine months.
The baby was born at thirty two weeks instead of the expected forty weeks.
So the baby was born eight weeks, or about two months, early.
This baby's corrected age is about seven months, and the test is chosen accordingly.
Corrected age is usually taken into account until about two years of age.
Without this correction, a premature baby's responses could wrongly be thought delayed for age.
Family-centered care sees the family not as a recipient of information but as a partner in decisions.
Parents know the child best; their observations of how the child reacts to sounds at home are very valuable.
Test results are explained to the family in clear, understandable language, without drowning them in technical terms.
The family's language, culture and priorities are respected; options are offered and decisions are made together.
The possibility of hearing loss can be a hard process for a family; this emotional process is met with understanding.
International consensus statements also accept partnership with the family as a core principle of early intervention.
A pediatric case history is a systematic interview covering risk factors and development.
For pregnancy and birth, ask about prematurity, neonatal intensive care and congenital infections.
Find out whether anyone in the family has hearing loss that began in childhood.
Record whether newborn hearing screening was done and what the result was.
Speech, language and motor milestones are assessed in comparison with peers.
A history of frequent ear infections and ear discharge is also asked about.
A family's concern about hearing is, even on its own, a finding that must be taken seriously.
The cross-check principle was described by Jerger and Hayes in 1976.
According to this principle, the result of a single test is not accepted as final until it is confirmed by another, independent test.
In children, behavioral tests are compared with physiological tests that rely on different mechanisms.
Tympanometry and the acoustic reflex show middle ear status and, indirectly, the auditory pathway.
If the results agree, confidence grows; if not, the cause is investigated and the test is repeated if needed.
This principle matters especially in children, because behavioral responses are easily affected by attention, fatigue and development.
The cross-check helps prevent both missed hearing losses and unnecessary diagnoses of hearing loss.
Now let us look at the findings of a purely example eighteen-month-old child.
In sound field VRA, the responses are around twenty to twenty five decibels, which looks normal.
Tympanometry is normal in both ears.
However, otoacoustic emissions are present in the right ear and absent in the left.
Because sound field responses reflect the better-hearing ear, a loss in the left ear may have been hidden.
The cross-check reveals this conflict; the next step is ear-specific testing with insert earphones and, if needed, ABR.
The test room should be a calm setting where the child feels safe, free of distracting objects.
Before the session starts, decide which information matters most and plan the test around this priority.
With young children, two people often work together: one runs the test and the other directs the child's attention.
For objective tests that need sleep, the appointment is timed around the child's usual nap time.
It is not always possible to get all the information in one session; spreading the assessment over several sessions is normal.
The information obtained and the child's level of cooperation are recorded at every session.
A clinical tip: do not report a child as having normal hearing based only on normal sound field responses.
Sound field responses reflect the better of the two ears; a unilateral loss cannot be seen this way.
Aim for ear-specific testing with insert earphones and a cross-check with OAE at the earliest possible session.
The family's concern and the developmental history are also important information alongside the findings.
A child's ear canal is small, and the same setting produces a higher sound pressure; this affects measurements.
Tests are chosen by developmental age, not chronological age; in premature babies, corrected age is used.
In family-centered care, the family is not just informed but is a partner in decisions.
Under the cross-check principle, behavioral results are confirmed with physiological tests.
Test yourself: when choosing a behavioral test method for a child, what is the deciding factor?
The correct answer is B: developmental age.
For example, for a two-year-old with delayed development, VRA may be more suitable than play audiometry.
In the next lesson we will learn behavioral observation audiometry, or BOA, used with the youngest babies.
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