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9 Evaluation of Speech Perception in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Table 9.2 Speech reception threshold tests
Test Description Age/Use
Body parts or familiar objects Points to body parts or familiar object Variable, depends on language; use when other tests too
Spondee pictures or objects Points to spondee pictures or objects and repeats the
The Children’s Realistic Inventory
of Speech Perception (CRISP) and
22,23,24,25
CRISP-Jr
word, which may increase attention
Closed set spondee test using picture book or on
computer
21
dicult
Uses when child has the language to identify the objects
With/without (threshold test) competing noise.
9.4.2 Closed-Set versus Open-Set Testing
Word recognition tests can be can be presented in either a
closed-set or an open-set format. In closed-set testing, the
number of possible items is restricted. Items might be numbers,
body parts, pictures, or alphabet letters to which the child will
point. The child being tested understands what all the possible
test stimuli are and will select his response from that limited
number of potential items. By simply guessing and pointing to
a picture, a child has some chance of attaining a correct score.
Open-set testing, on the other hand, oers no clues. The child is
asked to repeat what he hears without any clues. Any word in the
child’s vocabulary is a possibility. In some cases, the child may be
asked to repeat what he hears even if it is not a word (e.g., nonsense
syllables). Open-set testing is much more dicult than closed-set
testing, and it will frequently result in lower scores. However,
open-set paradigms will provide a more realistic picture of speech
perception capabilities in conversation. As soon as child is capable
of the task, open-set testing should be used because it will provide
a more accurate representation of how the child is performing compared with normal-hearing children of the same age. By the time a
child reaches kindergarten, open-set testing should be expected for
children who received optimal early intervention services.
9.4.3 Recorded versus Monitored Live
Voice Testing
Recorded testing has the advantage of being more easily comparable from test session to test session and from one audiologist
to another.31 It avoids the possibility of the tester modifying her
voice, either intentionally or unintentionally, to assist the child in
obtaining a higher score. On the other hand, recorded testing is
more time consuming and prevents the audiologist from making
the adaptations that are sometimes needed when testing young
children. A child may require more o-time between stimuli to
be able to attend than the recording allow, repetition of an item
if the child becomes distracted or begins to talk to a parent or
the test assistant, or time out for encouragement. Experienced
pediatric audiologists who are aware of the pitfalls can obtain
accurate results using monitored live voice (MLV) testing, but
MLV testing should be used only when it is not possible to perform recorded testing.
Table 9.3 shows speech perception scores for an 8-year-old
with normal hearing who was tested with both MLV and recorded
stimuli. It is clear that the MLV testing can overestimate the child’s
auditory functioning. The recorded testing was in agreement with
19,2 0,32
the parent’s and school’s description of the child’s functioning
and made a case for referring the child for an auditory processing
evaluation.
Pearl
MLV testing is often selected for young children because it
is easier for the child and audiologist than recorded testing.
However, MLV will frequently result in higher scores than
recorded testing, thus overestimating the child’s actual auditory
abilities. It is important to use recorded tests whenever the child
is capable of performing the task. Recorded testing will provide a
more accurate representation of auditory performance.
9.4.4 Phoneme Scoring versus WholeWord Scoring
Most of the tests used to evaluate speech perception are scored
according to whether or not the person correctly identifies the
whole word. If the person makes an error on one phoneme, the
entire word is scored as wrong, depriving audiologists of useful
information.
Boothroyd has written extensively about phoneme scoring
and its advantages and has developed tests that rely on phoneme
5,30,33,34
scoring.
test. By recording the phoneme errors that a child makes during
any speech perception test, it is possible to learn what parts of
the auditory spectrum are not being appropriately perceived.
For example, vowel errors indicate insucient low-frequency
information. Inability to perceive sibilants correctly indicates
Table 9.3 Word recognition testing for an 8-year-old using MLV and
recorded testing demonstrating dierent results
Conditions MLV Recorded
50 dB 100 100
35 dB 100 95%
50 dB, +5 SNR 100 64%
50 dB, 0 SNR 100 50%
35 dB, 0 SNR 88% 32%
Abbreviations: MLV, monitored live voice; SNR, signal-to-noise ratio.
Actually, phoneme scoring can be used with any
101
II Diagnosing Hearing Disorders in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Table 9.4 Closed-set speech perception tests
Test Description Age/Use
Northwestern University—
Children’s Perception of Speech
(NU-CHIPS)
Word Intelligibility By Picture
Identication (WIPI)
Alphabet Test
Auditory Numbers Test (ANT)
The Children’s Realistic Inventory
of Speech Perception (CRISP) and
CRISP Jr.
Children’s Auditory Recognition
with Digital Stimuli (CARDS)
35
36,37
38
39
22,23,24,25
40
Four-item, forced choice, picture-pointing test with four lists
of 50 words each, percent correct scoring
Six-item, forced choice, picture pointing test with six lists of
25 words each, percent correct scoring
Child points to one or two consonants on board Errors scored by phonemic similarity to the stimulus
Number perception test using cards with one, two, three or
more pictures of ants
Closed-set, four-item, forced- choice test using spondees
and dierent levels with competing noise
Six-item, forced choice, digital photographs displayed on
a computer tablet with six lists of 20 words each, percent
correct scoring, recorded by a female talker
Vocabulary 3–5 years
Vocabulary 4–6 years. Foils require ner auditory
perception than the NU-CHIPS
Assesses vowel perception using numbers
In book or computer format; may be used when
child can perform the task
3+ years
insucient high-frequency information or possible upward
spread of masking caused by too much low-frequency amplifica-
tion. Knowing the exact spectral bands of the phonemes that are
mis
perceived will provide even more specific information. This
information may make it possible to make changes in the frequency response of the child’s hearing aids or cochlear implants,
make earmold modifications, and to suggest auditory training
goals.
9.4.5 Half-List versus Full List
The issue of using only a half-list of words in a test versus using
the entire or full list has been debated in the field of audiology for
years. Obviously, using a full 50-word list reduces the chance of
scoring error, but when working with young children, time is of
the essence. It is necessary to acquire a great deal of information
in a short period of time; however, the necessity for speed does
not justify using fewer than the required number of stimuli to
obtain reliable results. Short lists should be used only when a
short-list protocol has been validated. The number of words
used must be sucient to obtain all the information necessary
to assess the child’s speech perception abilities. This assessment
can usually be achieved with 25 words on most tests, but not
with only 10 words. Except in rare cases, such as the Isophonemic
33
Word Lists,
which have been standardized as 10-word (30-pho-
neme) lists, 10 words will not provide a sucient number or
variety of stimuli to obtain an accurate score.
9.4.6 Use of a Carrier Phrase
Most word recognition tasks were designed to be used with a
carrier phrase. The carrier phrase alerts the child to attend and
places the word in a sentence context that more accurately represents its use in normal conversation. The carrier phrase usually
ends with a vowel so that the carrier phrase does not inuence
the word. Common carrier phrases are “you will say,” “show me
the,” “where is the,” or “tell me.”
9.5 Description of Children’s
Speech Perception Tests
9.5.1 Closed-Set Tests
Closed-set tests are useful for very young children who do not
have sucient vocabulary to perform on an open-set test or
when articulation is too poor for the audiologist to accurately
access production. Table 9.4 lists all closed-set tests with their
descriptions and uses (Video 9.4).
The tests vary from simple ones like the Auditory Numbers Test
(ANT),39 which requires pointing to the number of ants on a card,
to the Alphabet Test,38 which requires children to point to one or
two alphabet letters. On the Alphabet test, if the stimulus is [p]
and the child points to [b], the answer is wrong by only one distinctive feature (voicing). However, if the child pointed to [z], the
response would have been incorrect by three distinctive features
(voicing, manner, and place), indicating a lower score and a more
Table 9.6 Speech perception tests for very young children
Test Description Age/Use
Early Speech
Perception Test (ESP)
Subtest 1
56
ESP Test
ESP Test
Mr. Potato Head Task
Subtest 2 Spondee test Use when child has
56
Subtest 3 Monosyllabic words
Syllabication:
56
monosyllabic (shoe),
bisyllabic (two
syllables with unequal
stress, as in baby),
spondee (equal stress
on both syllables, as in
airplane), or trochee
(three syllables, as in
ice cream cone).
using primarily vowel
perception
57
Game to assess
perception through
play, e.g., “give Potato
Head the blue shoes”
35,36,37,38,39,40
Use when child has
the vocabulary to
identify words
the vocabulary to
identify words
Use when child has
the vocabulary to
identify words
Use when child has
the vocabulary to
identify words
102
9 Evaluation of Speech Perception in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Table 9.5 Summary of open-set word, phrase, and sentence recognition tests
Test Description Age/Use
Northwestern University Children’s
Perception of Speech (NU-CHIPS)
Word Intelligibility by Picture
Identication (WIPI)
Phonetically Balanced Kindergarten
41
(PBK)
Test
The Isophonemic Word Lists
Minimal Pairs Test
The Lexical Neighborhood Test
(LNT) and Modied Lexical
Neighborhood Test (MLNT)
University of Western Ontario
Plurals Test
Phrases in Noise Test (PINT)
Hearing in Noise Test (HINT)
49
HINT-C
for children
AzBio Sentence Test
51
AzBio
North American Listening in
Spatialized Noise-Sentences Test
(NA LiSN-S)
Bamford-Kowal-Bench Speech-inNoise Test (BKB-SIN)
Abbreviations: APD, auditory processing disorder; CI, cochlear implant; SNR, signal-to-noise ratio.
44,45
52
36,37
42
50
and Pediatric
53
33
43
46,47
48
Six-item, four lists, each with 50 monosyllabic words, percent correct scoring Open set for ages 3+ years
35
Four lists, each with 25 monosyllabic words, percent correct scoring Open set for ages 4+ years
Three lists of 50 words, percent correct scoring 5+ years
Fifteen lists of 10 consonant–nucleus–consonant (CNC) words, percent correct
scoring for whole words and phonemes
Twenty minimal pairs, words dier by one phoneme (e.g., bear/pear); examines
place, manner, or voicing or vowel place/height dierences, used for CI evaluations
LNT: two 50-item lists of monosyllabic words; MLNT: two 24-item lists of words
with two or three syllables; for both, half of the words are lexically easy and half are
lexically hard; percent correct scoring; used for CI evaluations
Five randomized lists of 30 words with simple plural forms (nal /s/ or /z/) to assess
high-frequency audibility, which is critical for learning new words
Prerecorded SNRs, estimates 50% correct threshold for simple phrases (such as
“brush his teeth”) in classroom noise, can repeat or act out phrase with doll
and
Traditionally an adaptive test that measures 50% correct threshold for sentences in
quiet or speech-shaped noise, but can be done at xed SNRs; used for CI evaluations
Fifteen or 16 lists of 20 sentences each with multitalker babble on separate channel,
percent correct scoring
Computerized adaptive test, measures sentence-in-noise thresholds for varying
noise locations and types of noise, often used for APD evaluations
Eighteen list pairs of sentences with prerecorded SNRs, estimates 50% correct
threshold for sentences in multitalker babble, scored for key words correct, formula
used to calculate SNR loss relative to normal hearing
49
School-age vocabulary
School-age vocabulary
3+ years
School-age vocabulary
3+ years
6+ years
5+ years
6+ years
5+ years
significant problem in auditory perception. When standardized
tests cannot be used, body parts or names of familiar objects can
be substituted as test stimuli. However, if a very small set of stimuli is used, the results must be interpreted with caution. Video 9.5
demonstrates closed set speech perception testing.
9.5.2 Open-Set Tests
Open-set testing, because it does not have a limited set from
which the listener selects an answer, is more dicult than
closed-set testing. The response is limited only by the vocabulary
of the person being tested. A summary of the most commonly
used open-set tests is provided in Table 9.5.
5,46,47,48,49,50,51,52,53
Monosyllabic word tests often provide more specific informa-
tion and are often more helpful in planning remediation than
sentence tests. However, some new sentence tests have been
developed that are demonstrating comparable or better results to
those obtained with monosyllabic word tests.
estimate recognition of conversational speech, including context.
Older children (12 years) and adults can be tested using the
more familiar Consonant-Nucleus-Consonant (CNC)54 or the
Northwestern University–6 (NU-6)55 word lists as well as the City
University of New York (CUNY) Sentences.4 As a child’s vocabulary
increases and skills improve, the more dicult tests should be used
35,36,37,38,39,40,41,42,43,44,4
50,51
Sentence tests
because they provide a measure of performance that can better be
compared with scores obtained for normal-hearing peers. Video
9.6 demonstrates open set speech perception testing.
9.5.3 Tests for Special Populations
Tests for Very Young Children
Because young children have limited vocabularies, tests need
to be selected with care to be certain that testing is assessing
auditory perception and not vocabulary knowledge. Possible
test stimuli for very young children include body parts, familiar
toys, or objects. Standardized tests are also available and should
be used whenever possible. Tests for very young children are
reviewed in Table 9.6.
Tests for Children with Profound Hearing
Loss Who Have Not Had Auditory Access with
Technology
Tests developed for children with profound hearing loss were
based on the assumption that a child will not be able to perform
the more commonly used tests. With newborn hearing screening
identifying aected infants within weeks of birth, and with
56,57
103
II Diagnosing Hearing Disorders in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Fi g . 9.1 Speech perception test protocol.
technology available to provide good acoustic access to almost
every child, most children born with any degree of hearing loss
can use standard tests. Some patients who are identified late or
who have not had access to early intervention with an auditory
therapy basis may suer from limited speech perception ability,
but with cochlear implants, expectations have changed. Tests for
children with profound hearing loss should be used only when
the child cannot perform on standard tests.
The tests most commonly used for children with profound
hearing loss are closed-set tests. These include the ANT,39 the Early
Speech Perception (ESP) Test,56 the Mr. Potato Head Task,57 and the
Alphabet Test.38 Other tests are the Minimal Auditory Capabilities
(MAC) Test58 and the Test of Auditory Comprehension (TAC).
59
9.6 Selecting and Developing
a Speech Perception Test
Protocol
The first thing to consider when developing a test protocol is
the purpose of the test. Is the test being performed to obtain the
best possible score? If that is the case, it would be best to select
very easy test materials on which the person can be expected
to do very well. On the other hand, if the purpose is to see how
the person compares to normal-hearing peers, testing must be
conducted with tests that would be used to test normal-hearing
peers. If the purpose is to monitor technology or technology settings, testing should be performed with each piece of equipment
alone, and also in whatever combinations the equipment is used.
If the purpose is to assess areas needing habilitation/rehabilitation and to plan for educational placement, it will be important
to monitor performance in dicult listening situations and to
select appropriate vocabulary level tests using both whole-word
and phoneme scoring.
9.6.1 Test Materials
The first step in selecting the appropriate test is to know the
child’s auditory language age (i.e., language developed through
listening) and auditory skill level, because speech perception
tests are performed using listening alone. Test materials must
be linguistically appropriate: neither too easy nor too dicult. It
may be necessary to select dierent tests for each ear if the two
ears function dierently. The evaluation report must be clear
about what tests were used in which condition so that results
can be appropriately interpreted. To obtain a complete picture
of a person’s auditory abilities, it may be useful to test monosyllabic words, nonsense syllables, and sentences, all of which
can be scored for number of words and phonemes correctly
identified.
Caution
A child who did not have early or sucient access to intelligible
speech or who has a decient cochlear nerve may have a sign
language or a speech reading vocabulary at a 9-year-old level
but have only a preschool-age vocabulary when using listening
alone without visual cues. Children who have early and consistent access to appropriate hearing technology will typically have
ge-appropriate vocabulary.
a
Fig. 9.1 describes the protocol for beginning testing. If a child’s
auditory language level is lower than 2 years, the ESP is a good
initial test, and if the auditory language age is 9 years, testing will
begin with a test at the level of the NU-6 or CNC.
If the child does extremely well, it is possible that a test has
been selected that is too easy. The subsequent step should be
to proceed to the next more dicult test and repeat testing. For
example, if a child obtains a score of 90% on the Northwestern
University Children’s Perception of Speech (NU-CHIPS),
is too easy. Testing could proceed by retesting with the NU-CHIPS
in an open-set format or by moving to the Word Intelligibility
by Picture Identification (WIPI),
Kindergarten (PBK) Test,41 the CNC, NU6, or Pediatric AZ Bio test,
depending on the child’s vocabulary level.
36,37
the Phonetically Balanced
35
the test
104
9 Evaluation of Speech Perception in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
9.6.2 Test Conditions with and without
Technology
When testing speech perception using earphones, it is standard
practice to test at 40 dB SL (sensation level; louder than the
pure tone average), or 40 dB above the SRT. A significant body
of research indicates that testing at this level is likely to provide
the best word recognition scores for people with normal hearing.
If the child has normal hearing, this level may be close to the
typical conversational level of 50 dB HL. However, if the child’s
speech threshold is 30 dB HL and speech perception is tested
at 70 dB HL, we are not seeing a realistic picture of how the
child hears normal conversation in daily listening situations. To
obtain a more realistic picture of how a child is performing in
day-to-day situations (i.e., functional listening), it is useful to
assess speech perception in soundfield at normal (50 dB HL/~ 65
dB sound pressure level [SPL]) and soft (35 dB HL/~ 50 dB SPL)
conversational levels in quiet as well as conversational levels in
noise (50 dB +5 signal-to-noise ratio [SNR]). If a child does well at
this noise level, additional testing should be performed at 50 dB
at 0 SNR and at 35 dB at 0 SNR.
It is important to note that one-time calibration procedures will
be necessary for speech perception tests that are designed for presentation levels in dB SPL (e.g., CNC, AzBio, Lexical Neighborhood
Test [LNT]). To calibrate speech stimuli in the soundfield, a sound
level meter can placed on a stand at the location of the patient’s
head while the patient is seated in the soundbooth (i.e., calibrated
location) and can be set to dBA or dB SPL. The calibration signal
(usually speech-shaped noise) should be selected on the compact
disc (CD) and played through the audiometer and soundfield
speakers into the soundbooth. The intensity of the calibration
signal can be adjusted on the audiometer dial to achieve the
desired presentation level (recommended level, normal, soft,
etc.) as measured with the sound level meter. The calibration is
necessary because stimuli are not recorded at equivalent volumes
across CDs, and simply adjusting the volume units (VU) meter will
not resolve the volume dierences.
Several tests listed in Table 9.5 (Hearing in Noise Test [HINT],
Phrases in Noise Test [PINT], Listening in Spatialized Noise—
Sentences [LiSN-S] Test, Bamford-Kowal-Bench Speech-in-Noise
Test [BKB-SIN], and AzBio) have published data to support
their reliability, validity, and list equivalency in background
46,47,48,49,50,51,52
noise.
should be used to determine appropriate signal levels and SNRs.
Bodkin et al60 reported on testing of 126 children with normal
hearing age 3 to 17. Testing in multiple noise conditions revealed
a mean score of 91 to 99% in dierent conditions for dierent age
groups. These results demonstrate that speech-in-noise testing
is possible even for very young children and should be part of
the standard test battery. By testing in more dicult conditions,
the audiologist will be able to identify children who may have
auditory processing problems and who require additional testing
or who may need additional auditory-based therapy. Children
with otitis media who are experiencing problems that indicate
diculty hearing in a classroom may also be identified.
When testing children with technology in the soundfield, test
monaurally, binaurally, and with the RM system to identify potential problems with individual pieces of equipment. For example,
binaural testing will not identify whether one hearing aid is
Test manuals or published data on the test
61
providing insucient gain, or whether speech perception with
one hearing aid is significantly poorer than with the other hearing
aid, and the audiologist will not know there is a discrepancy that
requires attention (Table 9.7).
Table 9.8 shows test results for a child who has poorer word
recognition in the right ear that is resulting in poor binaural
word recognition. If testing had been performed binaurally only,
the audiologist would not know that the child has good speech
perception in the left ear. Because aided gain is the same for both
ears, speech perception discrepancies may indicate that there is
some distortion in the right hearing aid or that the child has poor
auditory skills in the right ear and needs auditory training work
on the right ear alone.
Table 9.7 Poor word recognition in one ear when compared to the
binaural condition
Right HA Left HA Binaural
50 dB HL 72% 46% 76%
35 dB HL 56%
50 dB HL, +5 SNR 64%
Abbreviations: HA, hearing aid; HL, hearing level; SNR, signal-to-noise ratio.
Table 9.8 Poor right ear word recognition resulting in poor binaural
performance
Right aid Left aid Binaural
50 dB HL 72% 46% 76%
35 dB HL 56%
9.6.3 Test Modality
Testing in the auditory-only mode will provide information
about how the child is using auditory information. Auditoryonly testing is critical for monitoring technology to determine
whether adjustments need to be made to the technology and to
understand how the person functions when visual cues are not
available. Testing in the visual-only mode will provide information about how the child is using visual information, primarily
speech reading. Testing in the auditory-visual mode will provide
information about a combination of auditory and visual skills.
Audiological emphasis on testing in the auditory-only mode
does not imply that a child will be asked to ignore visual cues in
daily communication. Auditory-only testing is simply the best
way to obtain information about auditory skills and necessary
audiological modifications of technology to improve communication. Information about auditory perceptual skills is critical no
matter what communication approach the child uses.
9.6.4 Stimulus Presentation
Recorded testing is the preferred test method because it is most
repeatable. This makes it easy to compare test results over time.
Some young children who cannot sit still and attend consistently
may require testing to be adaptable, but with an experienced test
assistant, testing can usua lly be accomplished. For these children,
105
II Diagnosing Hearing Disorders in Infants and Children
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
MLV testing is easier to use. When MLV testing is used, the
audiologist must monitor the voice level using a VU meter to be
certain that the level is well controlled. When using MLV testing,
rate of presentation should be close to that of the recorded test. If
an adaptive test protocol is used (if test stimuli are eliminated or
words are repeated), this must be noted and taken into account
when describing test results. As children age and skills improve,
testing should advance to using recorded stimuli.
9.6.5 Scoring Speech Perception Tests
What is a good score on a speech perception test? Does it matter
how speech perception tests are scored? Yes, it does! If the
audiologist believes that a child is performing well on a speech
perception test, there is no reason to try to improve auditory
access, and the auditory therapist will not feel the need to work
on improving listening skills. If, on the other hand, test results
are perceived as being poor, the audiologist has a responsibility to improve auditory performance. Madell et al62 surveyed
audiologists and auditory therapists to determine what they
considered good speech perception. The authors were distressed
to learn that what was viewed as “good” speech perception for
children with hearing loss varied significantly—from 40 to 90%.
Respondents were asked whether children with hearing loss
needed to hear as well as children with normal hearing, and
respondents agreed that they did. If that is the case, tests need
to be scored in the same way as tests are scored for children
with normal hearing. Table 9.9 shows recommended scoring for
speech perception tests.
Reports should accurately report speech perception perfor-
mance. Children who are performing at 68% cannot be described
as having “good” or “excellent” speech perception. They do not. By
honestly reporting performance, all professionals working with
the children know that they have to work to improve performance.
Audiologists may need to change technology or technology settings, and teachers, speech-language pathologists, and auditory
therapists need to work on improving auditory skills.
9.7 Items to Consider When
Reviewing the Report of an
Audiologic Evaluation
When reviewing a report of an audiologic evaluation, it is
important to know how testing was accomplished. Was testing
accomplished as open- or closed-set; recorded or MLV; at what
sound level; and was each ear tested separately and binaurally
with technology? Closed-set MLV testing may be appropriate
for a 3-year-old, but it is not the appropriate test protocol for
Table 9.9 Recommended scoring for speech perception tests
Excellent 90–100%
Good 80–89%
Fair 70–79%
Poor < 70%
62
a 10-year-old in a mainstream setting. The NU-CHIPS35 is an
appropriate test for a preschool child or a child with a preschool
vocabulary, but it is no longer appropriate for a mainstreamed
third-grader, who should have a vocabulary significantly above
the preschool level.
Pitfall
Assessing a child’s speech perception capabilities with a test that
is too easy will result in an inated test score that will not provide
an accurate estimate of the child’s daily functioning.
If a child performs well binaurally at a normal conversational
level, the child will hear well within about 6 to 10 feet of the talker
in quiet. However, if the child does not do well at a soft speech
level or with competing noise, the child will have problems
hearing classroom conversation at school and discussion at home.
The audiologist will need to try to improve the child’s ability to
hear soft speech and to hear in noise. It may be possible to change
technology settings to improve performance. If the technology
cannot be adjusted, the test results indicate the need for a change
in technology (a dierent hearing aid or moving from a hearing
aid to a cochlear implant), or for the use of an RM system in many
listening situations for auditory access.
By recording and evaluating phoneme scoring, it is possible
to determine which phonemes are not being heard. It is, then,
possible to extrapolate the frequencies that the child cannot
access. For example, if a child is not hearing [s], it is likely that
there is insucient gain between 4,000 Hz and 8,000 Hz. Knowing
this specific frequency information will assist the audiologist in
determining how to change technology settings and in suggesting
to the auditory therapist what needs to be emphasized during
auditory therapy.
Pearl
Recording phoneme errors can assist in identifying specic areas
of the frequency spectrum that may be possible to access by
changing hearing aid or cochlear implant settings to improve
auditory performance.
9.8 Conclusion
It is critical that everyone working with a child who has hearing
loss have high expectations for what the child is capable of
achieving and what the technology is capable of providing. If
the child cannot hear some sounds, audiologists need to modify
the technology settings. If the child is using the best possible
hearing aid and cannot hear a portion of the speech signal, it
may be time to consider moving to cochlear implants. The goal
of audiologic management is to have the child hear as much
as possible to maximize auditory learning. By fully evaluating
106
Table 9.10 Speech perception evaluation form
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
Word Tests Right
Unaided
50 dB HL
Word score
Phonemes
35 dB HL
Word score
Phonemes
50 dB HL,
+5 SNR
Word score
Phonemes
50 dB HL,
0 SNR
Word score
Phonemes
35 dB HL,
0 SNR
Word score
Phonemes
Sentences
50 dB HL
35 dB HL
50 dB HL,
+5 SNR
Abbreviations: HL, hearing level; SNR, signal-to-noise ratio.
Left
unaided
Soundeld,
no technology
9 Evaluation of Speech Perception in Infants and Children
Right
technology
Left
technology
Binaural
technology
RM
technology
auditory skills, the audiologist can go a long way to improving
auditory functioning.
When a child performs well at normal conversational levels (50
dB HL/~ 65 dB SPL) but poorly for soft speech (35 dB HL/~ 50 dB
SPL) and in competing noise (50 dB HL +5 SNR), it is very easy to
demonstrate the need for an RM system in school and in other
dicult listening situations (e.g., ballet class, sports, the car,
restaurants). By comparing test results under several conditions
with and without the RM system, the child, parents, and school
district will be convinced of the need for consistent RM use.
Children who perform well at loud levels but poorly at normal and
soft levels will have diculty hearing everyday speech at home
and in school. This diculty may indicate the need for a change
in technology or technology settings, the need to use an RM on a
full-time basis, or the need to consider a move from hearing aids
to cochlear implants.
Table 9.10 is an example of a test form that can be used to
record test scores. At first look it appears to be daunting, and
not all boxes will be filled in. The more boxes that are filled in,
however, the more information the audiologist has by which to
make treatment decisions.
Speech perception testing oers the best opportunity for the
audiologist to learn about a child’s auditory performance and to
make critical modifications in technology and recommendations
for management. Although it may be time consuming, its value is
well worth the eort. In the long run, it may be one of the most
important services we can oer the children whom we have the
privilege to serve.
Discussion Questions
1. Which factors need to be considered in developing a test
battery for a 3-year-old with a severe hearing loss?
2. Which factors need to be considered in developing a test
battery for a 15-year-old with a mild hearing loss?
3. What are the considerations in selecting test levels?
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10 Middle Ear Measurement in Infants and Children
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copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
10 Middle Ear Measurement in Infants and Children
Chris A. Sanford and M. Patrick Feeney
Summary
Middle ear measurement is a fundamental component of the
audiologic test battery, and its importance is nowhere more
evident than in pediatric assessment. Tympanometry and acous-
tic reex testing are the basic components of the middle ear
test battery, which provides information about the middle ear,
cochlea, auditory nerve (cochlear nerve, cranial nerve VIII), auditory brainstem, and facial nerve (cranial nerve VII). Therefore,
the middle ear test battery is useful as a cross-check with other
physiologic and behavioral tests (see Chapter 6 for information
about hearing test protocols for infants and children).
However, because of the anatomical development of the con-
ductive mechanism of the peripheral ear over the first 6–8 months
of life, tests that we can readily use to detect middle ear status in
older infants and children with a 226-Hz probe tone provide little
useful information in young infants. An approach to this problem
using 1,000-Hz tympanometry and wideband acoustic immit-
tance (specifically, reectance or absorbance) measurements will
be discussed. This chapter will also focus on when and how to
conduct middle ear testing in children, including the interpretation of test results. Although a brief overview will be provided
here, it is assumed that the reader has a basic knowledge of the
principles of acoustics and aural acoustic immittance, which form
the foundation for current middle ear measurement.
Keywords
middle ear assessment, pediatric, immittance, tympanometry,
stapedial acoustic reex, wideband acoustic immittance
Key Points
The basic components of the pediatric immittance test
•
battery are tympanometry, acoustic stapedial reex, and
wideband acoustic immittance tests.
The pediatric immittance test battery provides information
•
about the middle ear, cochlea, auditory nerve (cochlear
nerve, cranial nerve VIII), auditory brainstem, and facial nerve
(cranial nerve VII).
Due to the anatomic development of the conductive mech-
•
anism of the peripheral ear over the rst few months of life,
alternative stimuli, test methods, and normative data are
needed to determine middle ear status in infants and young
children compared to older patients.
Information in this chapter, with a focus on the application
•
of pediatric-based test procedures and methods, may be
added to the clinician’s toolbox for implementing middle ear
measurements in infants and children.
1,2,3,4
10.1 The Role of the Middle Ear and
Developmental Aspects
The middle ear contains the tympanic membrane, ossicles, ligaments, muscles, and an air space. This system serves to transfer
acoustic vibrations in air to the uid-filled cochlea. If the middle
ear were removed from this process, a 60-dB hearing loss would
result. Sounds at more intense levels would reach the cochlea
through skull vibration. The gain in sound transfer to the cochlea
is provided in part by two simple machines. The area dierence
between the tympanic membrane and the oval window of the
stapes increases the force per unit area on the stapes footplate,
much as a thumbtack allows us to puncture wood with our
thumb. The second simple machine is a lever provided by the
sizes and orientations of the malleus and incus, which also
boosts sound energy at the stapes footplate. These two factors
combine for as much as a 30-dB gain in sound transfer to the
cochlea. If the middle ear were missing entirely, sound would
strike the oval and round windows of the cochlea approximately
in phase, causing an additional reduction in the eciency of
sound transfer to the cochlea, leading to the maximal conductive
hearing loss of 60 dB.
The acoustic stapedius reex (ASR) is a response of the auditory
system to high levels of sound. It is detected clinically by noting
a small change in acoustic middle ear function as the stapedius
muscle contracts to pull on the stapes and stien the annular
ligament in the oval window. The ASR, a bilateral eect, involves
activation of fibers in the cochlear nerve and brainstem, which
trigger a response from the motor nucleus of the facial nerve to
activate that nerve and contract the stapedius muscle. For this
cascade of events to occur, each station along the way must be
functional. Thus, the reex may be absent because of a lesion
anywhere along the pathway. By examining the pattern of ASR
responses for ipsilateral and contralateral stimulation, the audiologist derives a wealth of knowledge about the function of the
peripheral auditory system from the middle ear to the brainstem.
It has been demonstrated that infants with auditory dyssynchrony
may pass a newborn hearing screening (NHS) with otoacoustic
emissions (OAEs), a preneural phenomenon, while the auditory
brainstem response (ABR) and ASR are absent.5 This suggests a
role for the ASR as a tool for NHS when paired with OAE screening.
Both tests could be conducted with the same probe without the
need for more costly ABR screening.
There are significant changes in the human external and middle
ear over the first postnatal months of life that likely aect its
sound conduction properties.
of the bony portion of the ear canal wall and resulting decrease in
the length of the cartilaginous portion of the canal; (2) an increase
in the overall size of the ear canal; (3) a decrease in the density
6,7
These changes include (1) growth
109
II Diagnosing Hearing Disorders in Infants and Children
u
Madell et al., Pediatric Audiology: Diagnosis, Technology, and Management, 3rd Ed. (ISBN 978-1-62623-401-7),
copyright © 2019 Thieme Medical Publishers. All rights reserved. Usage subject to terms and conditions of license.
of the ossicles over the first 6 months of life due to ossification
and absorption of residual mesenchyme8; (4) changes in the orientation of the tympanic membrane to be more vertical9; and (5)
progressive stiening of the ossicular joints.7 Studies by Keefe et
al10 and by Sanford and Feeney11 using wideband acoustic immittance, an emerging tool for middle ear assessment, suggest that
the acoustic properties of the infant ear change markedly over the
first 6 months of life.
Pearl
Development of the external and middle ear over the rst 6 to
8 months of life results in tympanometric data that may not
accurately reect middle ear function when using a 226-Hz
probe tone. Therefore, 1,000-Hz tympanometry and wideband
assessment techniques provide greater sensitivity to middle ear
disorders in neonates and young infants than 226-Hz tympanometry does, and they should be standard practice for middle
ear assessment for infants under 10 months of age.
10.2 Some Basic Principles of
Middle Ear Measurement
An acoustic transfer function (ATF) can be thought of as the
ratio of the response of an acoustic system to the acoustic input.
During traditional tympanometry, the ear canal is hermetically
sealed, a tone is presented, and its level is monitored using
a microphone. The level of the tone is held constant using an
automatic gain control circuit while the static pressure in the
ear canal is varied using an air pump (Fig. 10.1). The frequency of
the probe tone is specified by the American National Standards
Institute (ANSI) as 226 Hz at a level ≤ 90 dB sound pressure level
(SPL).12 The ease of energy ow through the ear, or acoustic
admittance, as a function of frequency, Ya, is an ATF equal to the
ratio of total acoustic volume velocity of the source, u, to the
total sound pressure, p,
Yp=
a
The u is the rate at which the acoustic displacement over a
surface, such as a speaker cone, varies with time. Assuming a
constant-u source in clinical admittance systems, the voltage to
the probe-tone amplifier required to keep the tone at a fixed SPL is
directly proportional to Ya.
The term acoustic immittance refers to a family of ATFs, including acoustic admittance and its inverse, acoustic impedance, Za =
1/Ya. Ya can be represented in the complex plane as a vector composed of two components (acoustic conductance, Ga, and acoustic
susceptance, Ba), which can be plotted in Cartesian coordinates
(Fig. 10.2). We can solve for the admittance magnitude |Ya| by
using the Pythagorean theorem:
Y G B= +
Ga on the horizontal axis is the portion of Ya directly related to
energy transfer through the ear and ranges from zero (no energy
2 2
a a a
Fi g . 10.1 The basic components of a tympanometer. One transducer is
used for the presentation of the probe tone, which is monitored by the
microphone. The second transducer is used for the presentation of an
ipsilateral acoustic stapedius reex activator. The pump varies the air
pressure in the ear canal.
Fig. 10.2 Cartesian plot of the acoustic admittance vector. |Ya|
represents the magnitude of the admittance vector. The acoustic
susceptance B
acoustic conductance, G
system. The symbol θ
has both compliant (+) and mass (–) components. The
a
, is in phase with ow of energy through the
a
represents the admittance phase angle.
Y
transfer) to positive values to the right. The conductance is positive for the middle ear, in which frictional forces are responsible
or dissipating energy. This causes the admittance vector to lie in
f
the right half of the complex plane (Fig. 10.2). A condition of Ga
near zero might occur in the measurement of a uid-filled middle
ear with little or no acoustic energy transfer to the middle ear. Ba
is the portion of Ya related to energy storage in the system, which
is composed of two opposing forces: compliant susceptance (positive) and mass susceptance (negative).
The value Ba for a 1-cm3 volume of air at 226 Hz at sea level is
approximately equal to 1 mmho, the unit of admittance, making
it straightforward to calibrate admittance instruments using this
probe frequency. In a calibration cavity there would be no energy
transfer, so that Ga = 0. When a system such as the ear is at its
resonance frequency, around 1,000 Hz for adults, the positive and
negative values of Ba cancel, leaving Ga to dominate energy ow
through the system. In this case, the phase angle, θY, between the
admittance vector and the conductance would be 0°. The opposite situation occurs in the case of measurement in a calibration
cavity where Ga = 0, and θy = +90°, a pure compliant susceptance.
110
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