Vanessa Salisbury, Clinical Scientist, Brighton and Sussex University Hospital Trust

The Clinical Application of the HearLAB Cortical Evoked Response System For Determining Aided Benefit And

Adjustment of Hearing Aids in Children.

Vanessa Salisbury, Clinical Scientist, Brighton and Sussex University Hospital Trust

Dr Laura Booth, Clinical Scientist, Royal Berkshire Hospital NHS trust

EUHA 2010, Hannover

The Auditory Cortex

The end of the roadThe end of the road

NAL: Dillon, Van Dun, Carter, Gardner-Berry

EUHA 2010, Hannover

The auditory cortex

Auditory cortex orientationAuditory cortex orientation


EUHA 2010, Hannover

The Cortical Auditory Evoked Potential (CAEP)

• Also known as the P1, N1, P2 complex• Latency • P1- 60ms, N1- 100ms, P2- 180 ms

• Infant response• N1 absent in young infants • P1, N1, P2 mature at different rates (Kushnerenko

et al., 2002)• Maturation complete by 19 years old (Ponton et al.,

2000)

EUHA 2010, Hannover

Adult CAEP

AdultAdult

2.5

5.0

300 400

µV

0 100 200 500 600

0.0

-2.5

P2P2

N1N1P1P1


EUHA 2010, Hannover

Paediatric CAEP

• Infant CAEP

InfantsInfants

ms500 600300 400100 200-100 0

µV

0

5

10

-5

PP

NN


EUHA 2010, Hannover

Clinical uses of the CAEP

• Assessment of adult thresholds (Richards and De Vidi, 1995; Tsu et al., 2002)

• Children who are unable to provide reliable behavioural thresholds

• Renewed interest in the verification of hearing aid amplification in infants (Purdy, 2005)

• Universal newborn hearing screening • Confirming hearing loss at younger age• Fitting hearing aids at younger age - at least 60 % of children

fitted before 6 months (Wood et al., 2006)

EUHA 2010, Hannover

Hearing aid fitting in young infants

• Current U.K. best practice• Auditory Brainstem Response (ABR) threshold or

Auditory Steady State Response (ASSR) threshold• Real Ear to Coupler Difference (RECD)• DSL5

• Parental and professional observations • Provides valuable feedback regarding general

audibility of environmental sounds and speech• How do we measure speech audibility in young

infants?

EUHA 2010, Hannover

Speech Evoked CAEPs in Infants

• Clinical need for objective assessment of speech audibility

• Speech stimulus can be used for CAEP assessment (Ostroff et al., 1998)

• Speech is useful when testing aided function• Longer duration stimulus subject to hearing aid

processing• Speech audibility - aim of hearing aid fitting.

EUHA 2010, Hannover

Speech Evoked CAEPs in Infants

• Correlates well to behavioural thresholds (Purdy 2005; Tsu et al., 2002, Carter et al., 2010)

• Significant correlation to functional measures of hearing aid performance in children (Golding et al., 2007)

• Additional information for children with ANSD (Rance 2002)

EUHA 2010, Hannover

Speech evoked CAEPs in infants

• Not widely used in a clinical environment. • Variable waveform morphology and latency

particularly associated with infants (Ponton et al., 2000; Kushnerenko et al., 2002; Kurtzberg, 1984)• Maturation,• Mental alertness,• Movement,

• Experienced eye needed to interpret waveforms (Ponton et al., 2000)

EUHA 2010, Hannover

Current Speech evoked CAEP assessment methods

• Existing ERA equipment• Stimulus presented via soundfield• Aided and unaided assessment• WAV speech files

– Various speech sounds– Various intensity levels

• Experienced clinician interprets the results– Repetition of waveforms– Latency and morphology characteristics

EUHA 2010, Hannover

Current Speech Evoked CAEP assessment methods

• HearLAB• Developed at NAL laboratories, Sydney, Australia• Speech stimulus sampled from running speech

– /m/ (0.25 – 0.5 kHz),– /g/ (0.8 – 1.6 kHz), – /t/ (2 – 8kHz),

• 3 intensity levels– Soft speech (55dB), – conversational speech (65dB),– loud speech (75dB)

• Aided and unaided speech

EUHA 2010, Hannover

Hearlab Speech Stimulus

-20.0

-10.0

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100 1000 10000

Frequency

1/3

octa

ve S

PL

GAETAEMAEILTASS @ 65

EUHA 2010, Hannover

Automatic CAEP waveform detection

• Automatic waveform detection• Statistical analysis Hotellings T2 (p-value)

• ‘As good as if not better than the human eye’ • Normally hearing infants (Carter et al., 2010)

– 30 dB SL = 85% correctly identified as present when speech was audible

– 5% false alarm rate• Children with SNHL (Van Dun et al., submitted for publication)

– 10 dB SL = 75% correctly identified as present when speech was audible

– 5 % false alarm rate

EUHA 2010, Hannover

The HearLAB


EUHA 2010, Hannover

CAEP infant assessment

• Straightforward for an experienced paediatric audiologist

• Infant awake and facing speaker• Fed, watered, nappy changed!• Appropriate play• Maintain alert state• Minimise myogenic noise

• 3 electrode placement (vertex, mastoid, forehead (common)

EUHA 2010, Hannover

CAEP assessment

EUHA 2010, Hannover

HearLAB assessment screen


EUHA 2010, Hannover

Child 1- verifying speech audibility with a softband BAHA

• Child 1 has a right sided cleft lip and palate and developmental delay.

• 8 weeks old – bilateral asymmetrical moderate to severe conductive hearing loss, confirmed using ABR.

• 9 weeks – fitted with softband BAHA• 9 months old – unable to obtain reliable behavioural

data due to developmental delay• Child 1 recently discovered BAHA as a new toy!

Parents finding BAHA difficult to manage.• Unable to verify benefit of BAHA

EUHA 2010, Hannover

Child 1

EUHA 2010, Hannover

Child 1 – unaided CAEP results

EUHA 2010, Hannover

Child 1 aided CAEP results

EUHA 2010, Hannover

Child 1 - outcome• Without BAHA • CAEPs present for /t/ at 65 dB• CAEP was not present for /g/ at 65 dB but present at 75 dB.

• With BAHA • CAEP present for /g/ at 65 dB

• Conclusion• The BAHA provides significant benefit by making a wider range

of speech sounds audible at average conversational level.• Parents were reassured and encouraged by results -both unaided

and aided.• Subsequent VRA behavioural assessment confirmed a bilateral

moderate upward sloping conductive hearing loss

EUHA 2010, Hannover

Child 2 - verifying speech audibility with hearing aids

• 7 weeks old- bilateral moderate to severe sloping sensorineural hearing loss confirmed using ABR

• 9 weeks – fitted with Nios Micro hearing aids using sound recover

• 8 months – reliable behavioural assessment confirmed ABR levels were accurate and stable

• Required confirmation that full range of speech sounds were audible

EUHA 2010, Hannover

Child 2

EUHA 2010, Hannover

Child 2 – Aided CAEP results

EUHA 2010, Hannover

Child 2 – outcome

• CAEP was present for /g/ and /t/ at 65 and 55 dB with hearing aids in place.

• Conclusion – Hearing aids are maintaining the audibility of speech at soft and louder levels in both mid and high frequencies.

• Child 2’s parents – ‘we’re pleased to know his hearing aids are doing their job. It’s reassuring to see that he can hear speech’.

EUHA 2010, Hannover

Child 3- verifying high frequency speech audibility with hearing aids

• 6 weeks old – confirmed bilateral mixed profound hearing loss• 8 weeks old – fitted with bilateral hearing aids• 2 years old- Bilateral grommets inserted• Behavioural results confirmed bilateral severe hearing loss• 2yrs 10 months - recently became very difficult to test reliably

although results obtained indicate hearing levels are stable.• Parents are concerned that Child 3’s speech sounds ‘flat’• Clinical need to confirm hearing aids are providing access to

speech – particularly high frequencies.

EUHA 2010, Hannover

Child 3 – aided CAEP results

EUHA 2010, Hannover

Child 3 outcome

• CAEP present for /t/ at 65dB. /m/• CAEP absent for /m/ at 65 dB.• Child 3 is able to hear high frequency speech at least

at conversational level• Parents and clinicians reassured re. hearing aid fitting.• 55 dB speech would have been useful but Child 3

became too distressed. To be completed at next appointment.

EUHA 2010, Hannover

Child 4 – verifying hearing aid prescription

• Child 4 has downs syndrome • 8 months - diagnosed with bilateral moderate mixed

hearing loss using ABR and fitted with bilateral hearing aids

• 21 months - unable to obtain any reliable behavioural information.

• Child 1 recently removing aids. • No up to date behavioural information to verify

hearing aid prescription

EUHA 2010, Hannover

Child 4 – unaided CAEP results

EUHA 2010, Hannover

Child 4 – aided CAEP results (1)

EUHA 2010, Hannover

Child 4 - outcome

• Unaided• CAEP absent using /t/ and /m/ 65 dB

• Aided 1• CAEP absent for /m/ at 65 dB and 75 dB, • Present for /t/ at 65dB

• Response seen only to high frequency stimulus with current hearing aid prescription.

• Changed hearing aid prescription to increase gain in low frequencies. • Aided 2

• CAEP present for /t/ at 65dB• CAEP absent for /m/ at 65dB

• ABR repeated and showed a deterioration in hearing thresholds particularly in low frequencies. Hearing aid prescription altered and CAEP now present for both low and high freq speech at quiet and conversation speech sounds.

EUHA 2010, Hannover

Child 4 – Aided results (2)

EUHA 2010, Hannover

Child 5- confirm speech audibility with hearing aids.

• 11 days old – whooping cough, ECMO treatment • Developmental delay• 13 months – bilateral severe to profound

sensorineural hearing loss confirmed using behavioural and ABR data, hearing aid fitted.

• 3 years old – speech and language therapist concerned that he is able to hear speech

• Need to confirm speech audibility.

EUHA 2010, Hannover


EUHA 2010, Hannover

Child 5 outcome

• CAEP present for /t/ and /m/ at 65 dB with hearing aids

• A range of speech is audible at average conversational level.

• There is cortical activation to speech stimulus within the auditory cortex

• Informs speech and language therapy

EUHA 2010, Hannover

Child 6- Is speech audible?

• 3 years 9 months• Developmental delay including delayed speech

production• Recent MRI confirmed brain damage• Behavioural assessments inconsistent but indicate an

overall high frequency severe sensorineural hearing loss.

• DPOAEs present bilaterally.• Can she hear high frequency speech? • Does she need a hearing aid?

EUHA 2010, Hannover

Child 6 – Unaided CAEP results

EUHA 2010, Hannover

Child 6 – conclusion

• CAEP present to /t/ and /m/ at 65 and /t/, /g/ and /m/ at 55 dB

• High frequency speech is audible at average and quiet conversational levels.

• Parents reassured• Hearing aid not indicated• ? Implications for neurologist re. cortical activation.

EUHA 2010, Hannover

Child 7 – Auditory neuropathy spectrum disorder (ANSD)• Child 3 born 3 months premature• 5 months gestational age (g.a.) - diagnosed with Auditory

neuropathy spectrum disorder (ANSD) using ABR and CMs.• 10 months g.a.- reliable behavioural assessment shows an

asymmetrical moderate to severe hearing loss.• 10 months g.a. – Bilateral hearing aids fitted• Ongoing delayed speech development and attention

difficulties. He uses total communication.• Parents report fluctuating understanding of speech• ABR shows fluctuating response• 6 years old – A referral for consideration of cochlear

implantation has been made• Assessment of speech evoked CAEPs

EUHA 2010, Hannover


EUHA 2010, Hannover

Child 7 - outcome

• CAEP present for /t/ and /g/ at 65dB• Speech is audible for low and high frequency speech

sounds at average conversational levels ……today.• Indicates potential for speech development….today.

EUHA 2010, Hannover

Are Speech evoked CAEPs useful in clinical practice?

• Methodology straightforward and fun for an experienced paediatric audiologist and the parents.

• Allow ~ 45 minute appointment• Children are awake!• ‘Real world’ stimulus.• They can complement current audiology good practice• Infants too young for behavioural assessment• ANSD• Children for whom speech and or behavioural testing is not

reliable.

EUHA 2010, Hannover

Are Speech evoked CAEPs useful in clinical practice?

• Inform parents and clinician re. child’s access to speech

• Verify changes in hearing aid prescription.• Indicate further assessment or onward referral • Cochlear implant, • ABR under general anaesthetic/sedation/ evening

home visit• Inform other health professionals e.g. speech and

language therapy, neurology.• Indicate maturity of auditory system• Auditory training

EUHA 2010, Hannover

Is the Hearlab a useful clinical tool?

• Yes!

• Automatic waveform detection makes speech evoked CAEP assessment more accessible to audiologists whatever their experience.

• Analysis is consistent across clinicians.• Speech sounds cover relevant speech range both

for frequency and intensity.• Instant results!

EUHA 2010, Hannover

Is the Hearlab a useful clinical tool?

• However….• Automatic waveform detection could restrict new applications

of infant CAEPs• Software upgrades available to reflect up to date research

• Clinicians may want a wider range of speech sounds and intensity levels.• Software updates may be available should the clinical need

arise• Portability.• Overall, It has become an invaluable addition to our clinical

toolkit.

EUHA 2010, Hannover

Thank you!

• Dr Laura Booth, Clinical Scientist, Audiology Department, Reading, U.K.

• Dr Bram Van Dun, NAL laboratories, Sydney, Australia• Dr Rob Low, Clinical Scientist, Audiology department,

Brighton.

Documents

Vanessa Salisbury, Clinical Scientist, Brighton and Sussex University Hospital Trust