1. Dr Laura Booth, Clinical Scientist, Royal Berkshire Hospital NHS 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

2. The Auditory Cortex
EUHA 2010, Hannover

3. The auditory cortex
EUHA 2010, Hannover

4. The Cortical Auditory Evoked Potential (CAEP)
Also known as the P1, N1, P2 complex
Latency
P1- 60ms, N1- 100ms, P 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)
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5. Adult CAEP
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6. Paediatric CAEP
Infant CAEP
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7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. Hearlab Speech Stimulus
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15. 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

16. The HearLAB
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17. 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)
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18. CAEP assessment
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19. HearLAB assessment screen
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20. 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
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21. Child 1
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22. Child 1 – unaided CAEP results
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23. Child 1 aided CAEP results
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24. 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

25. 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

26. Child 2
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27. Child 2 – Aided CAEP results
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28. 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

29. 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

30. Child 3 – aided CAEP results
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31. 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

32. 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
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33. Child 4 – unaided CAEP results
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34. Child 4 – aided CAEP results (1)
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35. 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.
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36. Child 4 – Aided results (2)
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37. 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

38. Child 5 – Aided CAEP results
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39. 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

40. 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

41. Child 6 – Unaided CAEP results
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42. 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

43. 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

44. Child 7 – Aided CAEP results
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45. 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

46. 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

47. 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

48. 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

49. 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

50. 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.
EUHA 2010, Hannover