Behavioral measures of hearing in young children

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Behavioral measures of hearing in young children

• Lenore Holte, Ph.D.
• Department of Speech Pathology and Audiology
• Department of Pediatrics
• University of Iowa

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Pediatric audiologic evaluation

• importance of test battery approach (behavioral
  and objective measures)
• importance of history-taking
• thorough record review high risk factors for
  hearing loss?
• serial tests the ultimate goal is the pure tone
  audiogram, to predict audibility of speech

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Pediatric audiologic evaluation

• newborn hearing screen result parents may be
  unsure
• check speech and hearing milestones
• helpful to have access to estimate of cognitive
  age
• minimum response level vs auditory threshold

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How do we test the hearing of an infant or young
child?

• Behavioral / Psychophysical Measures
• Behavioral Observation Audiometry (BOA)
• Visual Reinforcement Audiometry (VRA)
• Conditioned Play Audiometry (CPA)
• Speech Audiometry

• Physiologic/ Objective Measures
• Auditory Brainstem Response (ABR)
• Otoacoustic Emissions (OAEs)
• Immittance Audiometry

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Behavioral Measures

• May require several visits to obtain complete
  audiogram
• Typically requires more than one examiner
• Related to experience of tester
• Need to be sensitive to the state of the child at
  the time of testing to know childs interests
• These techniques are also useful for older
  patients with developmental disabilities

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• A series of testing procedures have been
  developed that allow hearing assessment in very
  young children.
• These procedures take advantage of the childs
  developmental level
• Behavioral Observation Audiometry
• 0-6 months
• Visual Reinforcement Audiometry
• 7 months 2 years
• Conditioned Play
• 2 to 5 years

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Auditory Development

• Auditory development follows a series of fairly
  predictable steps
• 0-6 weeks normal hearing children startle,
  eye blink or widen eyes to sounds at
  40- 80 dB HL
• 4-7 months head turn laterally toward a sound
  speech at 20 dB HL warble tones at
  varying levels
• 7 24 mo. Level of signals needed to elicit a
  head turn drops.
• 24 months Conditioned play audiometry possible

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Auditory development

• ABR thresholds improve from 28 weeks to 40 weeks
  gestation
• ABR thresholds slightly better in adults than
  term babies
• Behavioral thresholds under 6 months of
  questionable validity, but show some maturation
• Small differences that do exist are due to middle
  ear maturation, perhaps some maturation
  (myelination) of auditory nerve fibers, but not
  due to cochlear differences between newborns and
  older children or adults.

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Behavioral observation audiometry (BOA)

• Unconditioned responses
• Used from 0 to 6 months age (developmental)
• Basic Principle / Technique
• Sudden and novel sounds presented
• Observe babys response to sound
• If a response is seen sound heard
• No response sound not heard

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BOA Stimulus Presentation

• Novel, interesting stimuli
• Sudden presentation to evoke an obvious response
• Noise makers (e.g., rattles etc)
• Measured and varied frequency spectra
• Premeasured intensity output
• Warble tones or frequency modulated (FM) tones
• Important to pay attention to level, distance and
  possible visual cues during presentation

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Responses to Sound

• Reflexive
• Startle
• Limb jerks
• Eye blinks

• Attentive
• Quieting or increased activity
• Change in breathing rate
• Onset or cessation of vocalizations
• Onset or cessation of crying
• Eye widening, brow furrowing or expectant look
• Smiling
• Head turning searching or localization

Source Northern Downs, 1991
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BOA

• unreliable method of threshold estimation for
  better ear only, due to biases in observations
• objective methods essential in this age range
• dont rely on BOA, either to rule out or diagnose
  hearing loss

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Visual Reinforcement Audiometry (VRA)

• BOA Relies on unconditioned responses to sound
• VRA Looking for conditioned responses to sound

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VRA

• By 6-7 months the child typically will have a
  head turn
• VRA is the process of presenting acoustic stimuli
  ? watching for a head turn ? then reinforcing
  that behavior by presenting a reward ? child then
  learns to respond to stimulus in order to seek
  reward

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Visual Reinforcement Audiometry
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VRA

• Can be done in sound field or via insert phones
• Direction of head turn is not critical. 1 speaker
  with reinforcer in the same visual line.
• 2 testers. 1 in room and 1 with audiometer
• Tester in the room has quiet toys and has the job
  of orienting the child to the center between
  stimuli
• Tester with the audiometer is presenting the
  stimuli and communicating with the 2nd tester.
• Parents need to not participate
• Both testers vote if the head turn is an actual
  response

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VRA

• Testing procedures are modified for speed
• Up 10 down 10 or up 10 down 20
• If child will wear phones
• 2000 Hz left, 2000 Hz right
• 500 Hz left, 500 Hz right etc.
• Speech stimulus name, bah bah bah etc.
• Range of reinforcers
• Need to be novel (maybe varied too) but not scary
• Toy that moves and lights up has been shown to be
  better than just a light or social praise.
• Dont want it to be so engaging that the child
  has to get it hence, kept in dark plexiglass
  lit up as required

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VRA

• Conditioning
• Normally developing kids can be conditioned at
  6-7 months
• By 1-2 years of age a child can be quickly
  conditioned
• Children with developmental delays may be delayed
• Premature children without other developmental
  delays by 6-8 months corrected age
• Yet, highly dependent on the childs state at
  time of session
• Habituation
• Occurs more quickly with children as they age
• By age 1.5 to 2 years - time with the child may
  be quite limited
• Maybe reduced by varying reinforcers giving
  breaks

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VRA

• Experienced Pediatric audiologists will tell you
  they can get accurate, ear specific audiograms at
  6 months of age.
• Not true for all clinicians
• Not true for all children
• Not true for all clinical settings
• It is not always possible to see a child 6 times
  in a month or to coordinate the times that the
  child is seen with his nap time, eating, mood
  swings etc.
• Minimum response levels approximate thresholds
  as child grows older

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Visual reinforcement audiometry (VRA)(slightly
different from COR)

• conditioned responses
• this is a powerful tool
• ages 6 months - about 30 months (Moore et al,
  1975) older children with developmental
  disabilities
• child is conditioned to pair speech or
  frequency-specific stimulus with lighted,
  sometimes animated, toy
• need a big enough booth
• may need serial tests
• COR requires localization

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VRA

• can be ear-specific (insert phones) or sound
  field
• requires two examiners (one boring) and
  distracter toy for best reliability and most
  information
• responses clearest with reinforcers (and speakers
  if SF) at 90 degrees azimuth
• training phase, testing phase
• condition child to pair sound and light at high
  levels (or tactile stimulus) then decrease level
  to find threshold

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Moore et al., JSHD, 1977 Effect of complexity of
reinforcer on maintaining VRA responses from
infants 12-18 months of age
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Schmida et al., JAAA, 2003

• of head-turn responses before habituation in
  2-year-olds
• 20 reinforced with moving video images
• 20 reinforced with mechanical moving toy
• Mean responses with video image (15)
  significantly higher than mean responses with
  moving toy (11)

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Widin et al., Ear and Hearing, 2000

• Follow-up VRA evaluations on babies enrolled in a
  multi-center newborn hearing screening study
• insert earphones
• began testing at 30 dB HL before conditioning
• required control trials
• successfully obtained ear-specific thresholds for
  speech, 1, 2, and 4 kHz obtained by VRA on 95 of
  3134 infants aged 8-12 months

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Intelligent VRA (iVRA)

• Computerized control of stimulus level and
  frequency
• Tester in booth is naïve to signal presentation
  and codes (presses a button) when head-turn
  occurs
• Reinforcer on one side
• Control (no stimulus) trials to get estimate of
  of false positive responses
• Threshold is level at constant correct on
  psychometric function
• In two senior honors theses here at Iowa, not
  found to be clinically practical or efficient

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Conditioned Play Audiometry (CPA)

• Appropriate for children from about 2-5 years of
  age.
• Not all 2 year olds are ready for this
• Basic Technique
• Child is trained to listen for a specific
  stimulus respond in a specific way ?
  Appropriate responses are reinforced
• Specifically, H-W procedure is adapted so the
  child is taught to listen, then put a peg in a
  board, drop a block etc, and upon doing so is
  rewarded socially

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Conditioned Play Audiometry (CPA)

• Ages 24-30 months up to 5 years
• ear-specific results
• frequency-specific stimuli
• AC and BC
• may need serial tests or long breaks
• conditioning phase
• testing phase

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Procedure

• Help the child hold a peg/block near the ear ?
  Present a sound that is known to be audible ?
  Help child to put the peg down ? praise/applaud
  etc
• Repeat several times until child can respond
  without help ? testing begins once the child
  learns the task sufficiently
• If the child cant respond consistently at this
  level go up or stop
• May be done earlier outside audiometric
  environment with a noisemaker (1st visual
  auditory ? then auditory alone)

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Procedure

• Stimuli used may be warble tones but preferably
  pure tones
• Obtain minimum information (e.g., thresholds at
  500 4000 Hz for both ears ? then 1000 2000
  Hz)
• Look for conditioned responsesdont accept a
  response that is too late or too early
• Habituation will occur with play audiometry as
  well
• Speed is important
• Lots of social praise
• Make activity fun
• May require multiple sessions
• May need to wait for the child to mature

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Procedure

• Best done with earphones
• May be first done in soundfield earphones
  introduced gradually
• 2 clinicians who can communicate with each other
• 1 runs the controls and the other plays
• Both judge
• Clinician with the child has a range of
  activities at hand. Relatively quiet, engaging
  but not over stimulating
• Need to establish rapport with the child

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CPA make sure toy is appropriate and not
difficult to manipulate

• blocks in bucket
• rings on pole
• pegs in board
• pieces in a puzzle
• computer pictures (BTNRH)

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• Children who are deaf can be conditioned to
  respond to a tactile stimulusthat way the lack
  of response you observe to acoustic stimulus can
  be interpreted more accurately.
• Upper age limit with play audiometry is very
  approximate.
• Audiometric testing is tedious and school age
  kids can respond well to modified play
  activities.
• Bribes etc are always good.

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Conventional audiometry

• Age 5 years and above
• frequent verbal praise
• breaks
• may modify response to suit child

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Tangible reinforcement operant conditioning
audiometry (TROCA)

• Tangible reinforcement, such as Cheerios,
  available when auditory stimulus is present (push
  a button)
• For severely disabled population, especially MR
• Homemade systems
• Not used much after development of ABR and OAE
• Can also use tangible reinforcers in CPA

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Speech audiometry SRT and SAT

• SRT
• Childrens spondees
• spondee pictures
• point to body parts
• questions and answers
• SAT
• localization
• CPA response
• bone-conducted SRTs and SATs

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Speech Discrimination /Word Recognition

• Closed set format child points to picture
  corresponding to word they hear
• Often done with live voice (unlike with adults)
• WIPI (Word Intelligibility by Picture
  Identification)
• Set of cards with 6 pictures on each
• 25 items
• Multiple lists
• NU-Chips (Northwestern University Childrens
  perception of speech test)
• 50 items
• Set of 4 choices
• Multiple lists

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Speech audiometry Word recognition

• PBK-50 (Haskins, 1949)
• phonetically balanced kindergarten vocabulary
• 3 lists of 50 words each
• open set
• ages 5 and up

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Speech audiometry Word identification

• Northwestern University Childrens Perception of
  Speech (NU-CHIPS)
• Elliott and Katz (1980)
• 50 monosyllables
• closed set picture identification
• caution below age 4

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Speech audiometry word identification

• Word Intelligibility by Picture Identification
  (WIPI)
• Ross and Lerman (1970)
• 25 sets of 6 pictures, some of which seem dated
• 4 lists
• closed set
• ages 5 and up

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Word identification for severely hearing-impaired
children CAT or MTS test (Erber)
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