Evaluating speech detection in aided infants and estimating pure tone thresholds in unresponsive adults: Auditory-evoked cortical potentials Harvey Dillon,

Evaluating speech detection in aided infants and estimating pure tone thresholds in unresponsive adults: Auditory-evoked cortical potentials Harvey Dillon, Bram Van Dun, Lyndal Carter, Kirsty Gardner-Berry HEARing CRC National Acoustic Laboratories (NAL) ASA, Audiology Now! www.hearingcrc.org With thanks to John Seymour, Suzanne Purdy, Maryanne Golding NAL : Dillon, Van Dun, Carter, Gardner-Berry

The need for a new measurement tool NAL : Dillon, Van Dun, Carter, Gardner-Berry

Evaluation of aided functioning in infants Universal new born screening Early fitting of hearing aids Need for an evaluation method Confirmation of fitting Fine-tuning needed Cochlear implant needed NAL : Dillon, Van Dun, Carter, Gardner-Berry

So baby, how does it sound? Objective hearing aid evaluation for: young infantsyoung infants difficult-to-test peopledifficult-to-test people NAL : Dillon, Van Dun, Carter, Gardner-Berry

Why the rush? Language ability 6 months after implantation NAL : Dillon, Van Dun, Carter, Gardner-Berry

Significant effect of age of fitting: p = 0.001* Early intervention leads to better language development at 6 months after fitting (n=90) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Why use cortical responses? NAL : Dillon, Van Dun, Carter, Gardner-Berry

Why cortical responses to evaluate hearing aid fitting in infants? Reliably present in awake young infantsReliably present in awake young infants More likely to correlate well with perceptionMore likely to correlate well with perception Can be elicited by a range of speech phonemes – close to desired outcomesCan be elicited by a range of speech phonemes – close to desired outcomes Stimuli handled reasonably by hearing aidsStimuli handled reasonably by hearing aids Can be very frequency specific if neededCan be very frequency specific if needed NAL : Dillon, Van Dun, Carter, Gardner-Berry

Overview of Learning Lab Cortical responses – Where from – Development with age – Typical waveforms Measuring infant cortical responses – video Research results –Effect of auditory experience – Cortical responses to different stimuli – Automatic detection of cortical responses – Sensation level, hearing loss, and noise – Relationship to functional hearing ability Clinical applications –Estimating hearing thresholds in adults – live demo –Assessing speech audibility for infants –Case studies Future possibilities NAL : Dillon, Van Dun, Carter, Gardner-Berry

FUNDAMENTALS OF CORTICAL RESPONSES NAL : Dillon, Van Dun, Carter, Gardner-Berry

IC: Form full spatial map, Parallel processing paths join, History dependent MSO: Detect interaural time LSO: Detect interaural level AVCN: Frequency analysis, PVCN: Timing well preserved DCN: Inhibitory circuits, pinna cue detection? Parallel processing Needs to be fed to develop & maintain Auditory System: Central Pathways Lateral lemnisci SC: Visual spatial map Cortex: Complex detection Thalamus: Auditory and visual map integrated, relayed to cortex Plastic, e.g following cochlear ablation Medial geniculate nucleus Sorting, comparing and categorizing Perception Corpus callosum VNLL: Fed by contralateral CN NAL : Dillon, Van Dun, Carter, Gardner-Berry

The end of the road NAL : Dillon, Van Dun, Carter, Gardner-Berry

Auditory cortex orientation NAL : Dillon, Van Dun, Carter, Gardner-Berry

Auditory cortex orientation

Hudson, 2009 + - + NAL : Dillon, Van Dun, Carter, Gardner-Berry

Auditory cortex and current sources Sussman et al (2008) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical responses in adults with normal hearing NAL : Dillon, Van Dun, Carter, Gardner-Berry

Adult 2.5 5.0 300400 µV 0 100200 500 600 0.0 -2.5 P2 N1 P1 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Adult grand mean waveforms at Cz Tones Speech NAL : Dillon, Van Dun, Carter, Gardner-Berry

Development of cortical responses with age NAL : Dillon, Van Dun, Carter, Gardner-Berry

Infants ms 500600300400100200-1000 µV 0 5 10 -5 P N NAL : Dillon, Van Dun, Carter, Gardner-Berry

Maturational effects on cortical evoked response morphology Ponton et al (2000) N=8-16 per grand meanN=8-16 per grand mean Cz siteCz site stimulus = 10 click train, 2 ms ISI @ 65 dB SLstimulus = 10 click train, 2 ms ISI @ 65 dB SL rate = 1.3/srate = 1.3/s NAL : Dillon, Van Dun, Carter, Gardner-Berry

2 years12 years Cell bodies Cell bodies Axonal neuro- filaments Axonal neuro- filaments  Fewer neuro-filaments in young children, especially in more superficial cortical layers thought to generate N1 (Ponton, Moore & Eggermont 1999)  I III IV V VI II NAL : Dillon, Van Dun, Carter, Gardner-Berry

Latency versus age Sharma et al NAL data NAL : Dillon, Van Dun, Carter, Gardner-Berry

MEASURING CORTICAL RESPONSES NAL : Dillon, Van Dun, Carter, Gardner-Berry

Practical demonstration (by video): speech sounds and infants Set-up – equipment diagram Video of infant being tested NAL : Dillon, Van Dun, Carter, Gardner-Berry

Practical implementation of cortical testing: HearLab Disclosure: NAL will get a royalty for each unit sold. Thank you: The HearLab development team – Teck Loi, Barry Clinch, Isabella Tan, Ben Rudzyn, Lyndal Carter, Dan Zhou, Scott Brewer NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

CAEP room set-up at the National Acoustic Laboratories Free Field Speaker Baby sits on parent’s lap in the centre of the room or in a high chair. NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

Videos Attaching electrodes 0  1:00 2.30  end Headband usage Putting in hearing aids Keeping alert carousel NAL : Dillon, Van Dun, Carter, Gardner-Berry

Keeping electrodes on the baby using a headband NAL : Dillon, Van Dun, Carter, Gardner-Berry

Keeping the baby awake! NAL : Dillon, Van Dun, Carter, Gardner-Berry

Tools for keeping baby quiet, alert, awake NAL : Dillon, Van Dun, Carter, Gardner-Berry

(More) tools for keeping baby quiet, alert, awake NAL : Dillon, Van Dun, Carter, Gardner-Berry

(Yet more) tools for keeping baby quiet, alert, awake NAL : Dillon, Van Dun, Carter, Gardner-Berry

Practical issues in measurement Averaging Electrode location Artefact rejection Filtering Number of runs Head support Interference – lighting, mobile phones, active electrodes NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

Electrode location Inverting Non-inverting + - Ground NAL : Dillon, Van Dun, Carter, Gardner-Berry

Artefact rejection Peak voltage > 150 µV Rms voltage Insufficient voltage NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

Head support Yes!! NAL : Dillon, Van Dun, Carter, Gardner-Berry

Reducing measurement variability (random electrical signals)  Speeding up measurements  Increasing validity of interpretation NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

Capacitive Coupling 50 Hz Passive Electrodes NAL : Dillon, Van Dun, Carter, Gardner-Berry

Capacitive Coupling 50 Hz Active Electrodes NAL : Dillon, Van Dun, Carter, Gardner-Berry

Capacitive Coupling 50 Hz Passive Electrodes Active Electrodes NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusions: Active on-scalp pre- amplification Electrical leads are less sensitive to: capacitive coupling electrical interference (because of low amplifier output impedance) capacitive coupling electrical interference (because of low amplifier output impedance) Inductive coupling electrical interference (because of gain within pre-amplifier)Inductive coupling electrical interference (because of gain within pre-amplifier) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Signal processing options Noise down by x  measurement time down by x 2 Several potential improvements under research NAL : Dillon, Van Dun, Carter, Gardner-Berry

RESEARCH RESULTS WITH CORTICAL RESPONSES NAL : Dillon, Van Dun, Carter, Gardner-Berry

Impact of auditory experience on cortical responses NAL : Dillon, Van Dun, Carter, Gardner-Berry

NAL Aided hearing impaired Infants and children (not all have P1) Children with CI (Sharma,2002) and NAL aided hearing impaired infants/children (N=40) using speech stimuli presented at 65 dB SPL. NAL : Dillon, Van Dun, Carter, Gardner-Berry

Maturation with time “in sound” Ponton and Eggermont 2007 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusion: Auditory system maturity The latency of cortical potentials indicate the maturity of the auditory system.The latency of cortical potentials indicate the maturity of the auditory system. Latency matures consistent with the time “in sound”; ( Ponton and Eggermont, 2007)Latency matures consistent with the time “in sound”; ( Ponton and Eggermont, 2007) …. provided implantation occurs by 3.5 years of age (Sharma, 2002)…. provided implantation occurs by 3.5 years of age (Sharma, 2002) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical responses to different sounds NAL : Dillon, Van Dun, Carter, Gardner-Berry

N1, P2 amplitude advantage at Cz in adults for all stimuliN1, P2 amplitude advantage at Cz in adults for all stimuli N1, P2 amplitude NAL : Dillon, Van Dun, Carter, Gardner-Berry

Multivariate Analysis of Variance Divide each record into 50 ms time binsDivide each record into 50 ms time bins Average data points within each time binAverage data points within each time bin Use these averages as variables in MANOVA analysisUse these averages as variables in MANOVA analysis MANOVA finds the combination of variables that best distinguishes two or more stimuliMANOVA finds the combination of variables that best distinguishes two or more stimuli Result is probability of two stimuli coming from different distributionsResult is probability of two stimuli coming from different distributions Time Voltage NAL : Dillon, Van Dun, Carter, Gardner-Berry

Number of infants (N=20) with significantly different cortical responses to pairs of stimuli Based on MANOVA at Cz, 101 to 500 ms post-onset, in eight bins each 50 ms m vs t m vs g t vs g NAL : Dillon, Van Dun, Carter, Gardner-Berry

Are /tae/ & /mae/ cortical responses different in hearing impaired children? 10 subjects (5 with poor hearing aid progress), 14 ears10 subjects (5 with poor hearing aid progress), 14 ears 8 infants 6-20 months, 2 children 4 & 10 years8 infants 6-20 months, 2 children 4 & 10 years 4 moderate, 8 severe, 2 profound ears4 moderate, 8 severe, 2 profound ears 64% had different responses based on individual ANOVA64% had different responses based on individual ANOVA 9 subjects, 9 ears9 subjects, 9 ears 6-12 years6-12 years sloping, mild-severe hearing losssloping, mild-severe hearing loss hearing aids fitted to NAL-NL1 but not optimallyhearing aids fitted to NAL-NL1 but not optimally 55% had different responses55% had different responses NAL : Dillon, Van Dun, Carter, Gardner-Berry

Grand Average n = 16 infants + MM OO OR UU AH EE SH SS ms 0.00 200.00 400.00 600.00 - NAL : Dillon, Van Dun, Carter, Gardner-Berry

aheemmooorshssuu ah7477121213 ee7681112109 mm468810107 oo7887131013 or7118712107 sh1212101312314 ss1210101010311 uu13971371411 Number of subjects (out of 20) with significant differences between responses NAL : Dillon, Van Dun, Carter, Gardner-Berry

Adults /tae/ /gae/ /mae/ 500 Hz 2 kHz Time (ms) Infants P1 P2 P N1 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusion: Cortical response shape for different speech sounds Future work: Cortical response to change, as a measure of discrimination Cortical response shape for different speech sounds, and tone bursts are similar, but not identical, in shape across stimuli. Cortical responses to sounds presented in isolation are better suited as indicators of detection. Cortical response shape for different speech sounds, and tone bursts are similar, but not identical, in shape across stimuli. Cortical responses to sounds presented in isolation are better suited as indicators of detection. NAL : Dillon, Van Dun, Carter, Gardner-Berry

Three speech sounds: /m/ /g/ /t/ NAL : Dillon, Van Dun, Carter, Gardner-Berry

Automatic detection of cortical responses NAL : Dillon, Van Dun, Carter, Gardner-Berry

Why not obligatory cortical responses? variable shape across agesvariable shape across ages variable shape with auditory experiencevariable shape with auditory experience variable shape from person to personvariable shape from person to person variable shape from time to time (state of person, especially sleepiness)variable shape from time to time (state of person, especially sleepiness) variable shape with stimulusvariable shape with stimulus Variable shape with inter-stimulus intervalVariable shape with inter-stimulus interval high skill level needed to read responses An automated method of response detection and response differentiation NAL : Dillon, Van Dun, Carter, Gardner-Berry

Desirable characteristics No reliance on a templateNo reliance on a template Able to use information from contributing portions of waveformAble to use information from contributing portions of waveform Able to discount non-contributing portions of waveformAble to discount non-contributing portions of waveform Hotellings T 2 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Analysis using Hotellings t 2 statistic Divide each record into 50 ms time binsDivide each record into 50 ms time bins Average data points within each time bin Average data points within each time bin Use these averages as variables in Hotellings t 2 analysis Use these averages as variables in Hotellings t 2 analysis Result is probability of the waveform being random noise Result is probability of the waveform being random noise X = a 1 X 1 + a 2 X 2 +........ + a 9 X 9 Test: is there any set of weighting coefficients for which X ≠ 0? Time Voltage X3X3 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Presentation of average response in series

Receiver Operating Characteristics – Expert judges 1 - Specificity Sensitivity d’ NAL : Dillon, Van Dun, Carter, Gardner-Berry

ROC – 200 repetitions; adults with normal hearing to moderate loss - 10 dB 0 dB 10 dB NAL : Dillon, Van Dun, Carter, Gardner-Berry

d’ results - for 200 stimuli NAL : Dillon, Van Dun, Carter, Gardner-Berry

d’ results - for 60 stimuli For hit rate of 80% and false alarm rate of 5%, d’=2.5 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Infants: Hotellings versus experts Normal hearing infants aged 7 to 16 months adults NAL : Dillon, Van Dun, Carter, Gardner-Berry

Effect of sensation level, hearing loss, and unrelated EEG or muscle noise NAL : Dillon, Van Dun, Carter, Gardner-Berry

Growth of amplitude with SL adults; tonal stimuli NAL : Dillon, Van Dun, Carter, Gardner-Berry

Loudness growth above threshold Hellman & Meiselman, 1990 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Effect of response amplitude on detectability P<0.05 100 epochs Adults, tonal 10, 20, 30 dB SL NAL : Dillon, Van Dun, Carter, Gardner-Berry

Detectability (adults; tonal stimuli) P=0.05 P=0.01 P=0.001 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Significant responses – normal hearing and hearing impaired Adults; tonal stimuli (n=100 or 200) NAL : Dillon, Van Dun, Carter, Gardner-Berry

0.001 0.00001 0.0000001 0.000000001 0.01 0. 1 0.0001 P=0.05 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Proportion with responses present - adults NAL : Dillon, Van Dun, Carter, Gardner-Berry

…….. but infants move around ! NAL : Dillon, Van Dun, Carter, Gardner-Berry

Residual noise level rms noise = standard deviation / √n NAL : Dillon, Van Dun, Carter, Gardner-Berry

Residual noise levels (for 100 epochs) 0 5 Awake adults Awake infants But also larger responses NAL : Dillon, Van Dun, Carter, Gardner-Berry

Growth of amplitude with SL Normal hearing infants Normal hearing adults Hearing impaired adults Hearing impaired infants NAL : Dillon, Van Dun, Carter, Gardner-Berry

P=0.05 Detectability versus residual noise - infants - More detectable NAL : Dillon, Van Dun, Carter, Gardner-Berry

Proportion with responses present (p<0.05) – normal hearing infants; 100 epochs NAL : Dillon, Van Dun, Carter, Gardner-Berry

Detection of speech sounds NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusions: Detecting cortical response presence Large responses are more easily detectedLarge responses are more easily detected Response amplitude grows with sensation levelResponse amplitude grows with sensation level Response amplitude at low SL is larger for people with sensorineural hearing loss that for people with normal hearingResponse amplitude at low SL is larger for people with sensorineural hearing loss that for people with normal hearing Responses are more easily detected when residual noise is low (<3.4 µV for infants; < 1.5 µV for adults)Responses are more easily detected when residual noise is low (<3.4 µV for infants; < 1.5 µV for adults) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical responses and functional performance Do cortical responses tell us about real-life auditory performance? NAL : Dillon, Van Dun, Carter, Gardner-Berry

Parents are asked to describe their baby’s aural/oral skills based on real-life experiences (listening in quiet and in noise and alertness to environmental sound) Scores are assigned based on the number of observed behaviors and how frequently these occur. Final overall score of 0 – 40 can be calculated (and reported as a percentage). Parent’s Evaluation of Aural/oral performance in Children (PEACH) Questionnaire NAL : Dillon, Van Dun, Carter, Gardner-Berry

Results: PEACH score by age Normative data curve NAL : Dillon, Van Dun, Carter, Gardner-Berry

Functional deficit vs number of cortical responses present at N = 24; p = 0.001 12 sensorineural 7 auditory neuropathy 5 multiply disabled NAL : Dillon, Van Dun, Carter, Gardner-Berry

Functional deficit versus cortical score * All aided children r s =0.60; n=24; p = 0.001 * SN only r s =0.61; n=12; p = 0.02 * MD only r s =0.82, n=5; p = 0.04 * AN only r s =0.36; N=7; p = 0.22 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusions: Cortical responses and functional performance The greater the number of speech sounds that result in cortical responses in aided infants, the greater the functional performance in real life, on averageThe greater the number of speech sounds that result in cortical responses in aided infants, the greater the functional performance in real life, on average NAL : Dillon, Van Dun, Carter, Gardner-Berry

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

Estimating hearing thresholds in non-responsive adults Elderly infirm – stroke, dementia Workers’ compensation NAL : Dillon, Van Dun, Carter, Gardner-Berry

Practical demonstration pure tones and adults Set-up – equipment diagram Screen sequence Electrode attaching Actual test – insert phones, pure tones. NAL : Dillon, Van Dun, Carter, Gardner-Berry

Good agreement between CAEP and audiometric thresholds in awake adults Tsui, Wong & Wong 2002 NAL : Dillon, Van Dun, Carter, Gardner-Berry

From: Rickards, F. et al (1996) Cortical Evoked Response Audiometry in noise induced hearing loss claims. Aust. J. Otol. 2 (3) NAL : Dillon, Van Dun, Carter, Gardner-Berry

Test sequence 110 60 85 100 105 95 90 80 75 70 65 55 50 45 40 35 30 25 20 15 5 10 0 Response absent P > 0.05 Response present P < 0.05 Evaluation using HearLab Automated response detection 40 ms tone bursts NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical threshold vs behavioural threshold - adults NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical thresholds minus Behavioral thresholds 68% +5 dB 84% +10 dB 91% +15 dB NAL : Dillon, Van Dun, Carter, Gardner-Berry

Davis (1965) Cortical evoked potential versus behavioural thresholds NAL : Dillon, Van Dun, Carter, Gardner-Berry

Conclusions: Estimating behavioural thresholds in hearing-impaired adults Cortical thresholds overestimate behavioural thresholds by 2.4 dB, on averageCortical thresholds overestimate behavioural thresholds by 2.4 dB, on average Standard deviation of cortical – behavioural threshold differences is 6.3 dBStandard deviation of cortical – behavioural threshold differences is 6.3 dB Applications: hearing compensation, clients unable to respondApplications: hearing compensation, clients unable to respond NAL : Dillon, Van Dun, Carter, Gardner-Berry

Cortical potentials to assess speech audibility for infants NAL : Dillon, Van Dun, Carter, Gardner-Berry

Clinical implications of corticals Significant response is obtained to speech at 65 dB SPL No significant response is obtained to speech at 65 dB SPL or to speech at 75 dB SPL Morphology normal for age Morphology abnormal for age Low residual noise High residual noise All is well Repeat test Re-check fitting; Consider all options Draw no conclusion ! NAL : Dillon, Van Dun, Carter, Gardner-Berry

Noisy results - chewing NAL : Dillon, Van Dun, Carter, Gardner-Berry

Clinical implications of corticals (cont) No /t/ response Draw no conclusions from missing response ! Mixed results (and noise is low) No /g/ response No /m/ response Review HF gain or loss estimate Review mid-freq gain or loss estimate Mixed results (and noise is high) Review LF gain or loss estimate NAL : Dillon, Van Dun, Carter, Gardner-Berry

Hearing loss at birth ….. for parents Parental denial Working towards a solution Pessimism and hopelessness Unaided testing at conversational levels Aided testing at conversational levels NAL : Dillon, Van Dun, Carter, Gardner-Berry

Some recent cases Hsiuwen Chang NAL : Dillon, Van Dun, Carter, Gardner-Berry

No /m/ response NAL : Dillon, Van Dun, Carter, Gardner-Berry

Case 1 Age at aided cortical testing –Visit 1 6 weeks old (Initial hearing aid fitting day) –Visit 2 3 months old No cortical responses, and the results helped the parents accept the need for cochlear implants NAL : Dillon, Van Dun, Carter, Gardner-Berry

Tone-burst ABR (Estimated levels in dB nHL) 500 Hz1000 Hz2000 Hz4000 Hz Right>95 Left>95 Estimated Audiogram (dB HL) at Visit 1 500 Hz1000 Hz2000 Hz4000 Hz Right859095 Left859095 Estimated Audiogram (dB HL) at Visit 2 500 Hz1000 Hz2000 Hz4000 Hz Right90100105 Left90100105 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Visit 1 Increase gain at all frequencies P < 0.05 ? …. No NAL : Dillon, Van Dun, Carter, Gardner-Berry

Visit 2 NAL : Dillon, Van Dun, Carter, Gardner-Berry

The infant received bilateral cochlear implantations at 5 months of age. Email from the baby’s parents ~ “Thank you so much for the information you gave us on the previous testing as it helped us with our decision to proceed with the implants.” NAL : Dillon, Van Dun, Carter, Gardner-Berry

Case 2 Age at aided cortical testing –Visit 1 13 weeks old –Visit 2 17 weeks old –Visit 3 21 weeks old Hearing aid fitting at 8 weeks of age No cortical responses, even after hearing aids have been increased in gain for the third time and the parents don’t want a cochlear implant for their baby NAL : Dillon, Van Dun, Carter, Gardner-Berry

Estimated Audiogram (dB HL) at Visit 1 500 Hz1000 Hz2000 Hz4000 Hz Right9080 85 Left8575 95 Estimated Audiogram (dB HL) at Visit 2 500 Hz1000 Hz2000 Hz4000 Hz Right10090 95 Left9585 95 Estimated Audiogram (dB HL) at Visit 3 500 Hz1000 Hz2000 Hz4000 Hz Right100 Left100 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Visit 1 Increase gain at all frequencies NAL : Dillon, Van Dun, Carter, Gardner-Berry

Visit 2 Right aidedLeft aided Increase gain at all frequencies NAL : Dillon, Van Dun, Carter, Gardner-Berry

The parents still believe that their baby boy can be oral by using hearing aids. They are hoping to see that their baby can benefit from more powerful hearing aids. The baby’s hearing aids were changed from Siemens Explorer 500 P to Phonak Una SP after Visit 3. NAL : Dillon, Van Dun, Carter, Gardner-Berry

Case 3 Age at aided cortical testing –Visit 1 4.5 months old –Visit 2 5.5 months old Hearing aid fitting at 5 weeks of age Corticals provided reassurance about the baby hearing well NAL : Dillon, Van Dun, Carter, Gardner-Berry

Tone-burst ABR (Estimated levels in dB nHL) 500 Hz1000 Hz2000 Hz4000 Hz Right40DNT6070 Left40DNT7080 Estimated Audiogram (dB HL) at Visit 1 500 Hz1000 Hz2000 Hz4000 Hz Right30405565 Left30456575 Estimated Audiogram (dB HL) at Visit 2 500 Hz1000 Hz2000 Hz4000 Hz Right40455565 Left40506575 NAL : Dillon, Van Dun, Carter, Gardner-Berry

Visit 1 Increase low- and mid- frequency gain NAL : Dillon, Van Dun, Carter, Gardner-Berry

Email from mother: “We feel very relieved, as our faith has been restored in the hearing aids as a result of what we discovered from the results.” NAL : Dillon, Van Dun, Carter, Gardner-Berry

Case 4 Age at aided cortical testing –Visit 1 8 months old –Visit 2 9 months old Hearing aids have been increased in gain two weeks before the second visit. Hearing aid fitting at 9 weeks of age Too few significant cortical responses, and the aid gain was increased, resulting in more cortical responses NAL: Dillon, Van Dun, Carter, Gardner-Berry

Estimated Audiogram (dB HL) at Visit 1 500 Hz1000 Hz2000 Hz4000 Hz Right455055 Left45556555 Estimated Audiogram (dB HL) at Visit 2 500 Hz1000 Hz2000 Hz4000 Hz Right555055 Left55 6555 NAL: Dillon, Van Dun, Carter, Gardner-Berry

Visit 1 Visit 2 NAL: Dillon, Van Dun, Carter, Gardner-Berry

Case 5 Age at testing: 4.5 years Multiple disabilities A reliable behavioural audiogram has not yet been obtained. A case where cortical testing was not possible NAL: Dillon, Van Dun, Carter, Gardner-Berry

She was wiggling all the time.

This is the quietest state she could be, but only lasted for a few seconds. NAL: Dillon, Van Dun, Carter, Gardner-Berry

Cortical testing at 8 months of age, nine days after the initial hearing aid fitting A case where the unaided /m/ was present but the aided /m/ was absent. NAL: Dillon, Van Dun, Carter, Gardner-Berry

Estimated Audiogram 500 Hz1000 Hz2000 Hz4000 Hz Right40354045 Left40354045 NAL: Dillon, Van Dun, Carter, Gardner-Berry

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

Hearing Aid Coupler Gain at 65 dB SPL Input 250 Hz500 Hz1000 Hz2000 Hz4000 Hz <0071520 * Both hearing aids are set the same. NAL: Dillon, Van Dun, Carter, Gardner-Berry

Application for auditory neuropathy spectrum disorder (AN) 20% of babies found to have hearing loss at birth in NSW have AN20% of babies found to have hearing loss at birth in NSW have AN Management unclear (no device, FM system, hearing aid or cochlear implant)Management unclear (no device, FM system, hearing aid or cochlear implant) Rance showed close relationship between cortical response in older children and benefit from hearing aidsRance showed close relationship between cortical response in older children and benefit from hearing aids ABR not indicative of behavioural thresholdsABR not indicative of behavioural thresholds NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Problem 1.In babies with ANSD we can’t predict the audiogram like we can for a baby with a typical sensory hearing loss. 2.We can’t predict speech discrimination ability. What approach to amplification & early intervention do we recommend? NAL: Dillon, Van Dun, Carter, Gardner-Berry

State-wide Infant Screening of Hearing (SWIS-H) Population based Universal newborn hearing screening program in NSW, Australia (AABR used for both well babies & NICU babies) Babies diagnosed with a bilateral, moderate or greater hearing loss. Sensory/Permanent conductive L. Murphy. Presented at the International Newborn Hearing Screening conference, Lake Como, Italy 2006 NAL: Dillon, Van Dun, Carter, Gardner-Berry

500 1k 2k 4k 8k 0 10 20 30 40 50 60 70 80 90 100 110 FREQUENCY (Hz) When we diagnose a young baby with a hearing loss we use Auditory Brainstem Response (ABR) testing and track wave V down to threshold. The wave V thresholds across different frequencies can then be used to predict an audiogram. Problem 1: How can we work out the degree of the hearing loss when there is no ABR waveform? NAL: Dillon, Van Dun, Carter, Gardner-Berry

0 10 20 30 40 50 60 70 80 90 100 110 500 1000 2000 4000 HEARING LEVELS IN DECIBELS FREQUENCY (Hz) Problem 2: How do we work out what a baby’s speech discrimination ability is like? 0 10 20 30 40 50 60 70 80 90 100 110 Child A Child B 500 1000 2000 4000 Speech discrimination score = 87% Speech discrimination score = 32% NAL: Dillon, Van Dun, Carter, Gardner-Berry

What do we recommend to parents when we’re walking in blind! NAL: Dillon, Van Dun, Carter, Gardner-Berry

Aims & Measures: 1.Predict whether average hearing levels are: <80 dBHL (hearing aid range) >80 dBHL (cochlear implant range) 2. Predict whether auditory function is significantly affected (with the view to look at speech discrimination ability in the future) 1.Cortical Auditory Evoked Potentials a)Presence/absence of cortical response to different frequency stimuli. 2.Functional auditory ability: a)IT-MAIS and/or b)PEACH NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Congenital ANSD & Degree of hearing loss Total No.= 62 ears (NAL ANSD population – multiple studies) Profound : Cochlear Implants (16 ears): 2 unilateral CI 4 bilateral. Moderate : 1 proceeded with a unilateral CI. Mild : No CIs at present Easy ! Nothing to lose Easy! Less to lose Hard Severe : Cochlear Implants (13 ears) 6 proceeded with a unilateral CI. NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Unaided CAEPs present. Unaided CAEPs absent. Hearing likely to be normal-mild. Hearing loss likely to be moderate- severe. Hearing loss more likely to be profound. Unaided CAEPs absent. Aided CAEPs present. Aided CAEPs absent. Group 1 4FA <80 dBHL = 7 subjects Group 2 4FA >80 dBHL = 8 subjects Q 1. Are speech sounds audible? Scenario 1Scenario 2Scenario 3 NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Q 2. Are there signs that auditory functional ability might be affected? Score <30% Score >30% Rance et al, 2002, Ear & Hearing Vol. 23(3) NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM CAEP result assumptions Assumed audibility needed to be >=25 dBHL for each stimulus to elicit a response (audibility calculator). Assumed PTA thresholds didn’t change significantly between CAEP testing & the acquisition of reliable PTA results. Keep in mind: Functional assessments weren’t always performed close to the time of CAEP testing. Speech sounds used for CAEP testing need to be at a high enough level above threshold (i.e. sensation level) to elicit a response. Should be audible Less audible Inaudible Expect CAEP Less likely to see CAEP Don’t expect CAEP NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Presence/Absence CAEPs < 80dBHL n= 7 subjects in group (12 ears) n= 36 responses to analyze (m, g, t) 2 subjects subsequently found to be under-fitted for at least 2/3 responses. 5 subjects Should have had reasonable audibility so CAEP responses were expected for at least 2/3 stimuli bilaterally. Present (for at least 2/3 responses bilaterally) 3 subjects Absent (for at least 2/3 responses bilaterally) 2 subjects Will these ones demonstrate good speech discrimination long term? CAEPs were absent for at least 2/3 stimuli so CAEPs guided appropriate recommendation to review fitting & management. Will these ones demonstrate poor speech discrimination long term? 1 abnormal PEACH at 2 years & 1 normal PEACH at 12 mths but under review 1 normal PEACH 1 no concerns regarding auditory behavior 1 unknown. 1 abnormal PEACH 1 inconsistent functional audibility results (normal PEACH at 7 mths but abnormal IT-MAIS at 13 mths) NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Presence/Absence CAEPs > 80dBHL n= 7 subjects in group (12 ears) n= 36 responses to analyze (m, g, t) 6 subjects subsequently found to have poor audibility (even high gain hearing aids wouldn’t have been sufficient due to severity of loss) 1 subjects (only 1 ear) Should have had reasonable audibility so CAEP responses were expected for at least 2/3 stimuli in one ear. Present (for at least 2/3 responses bilaterally) 0 subjects Absent (for at least 2/3 responses bilaterally) 1 subjects CAEPs were absent for all stimuli tested bilaterally so CAEPs prompted appropriate recommendation to review fitting & management. Will this baby demonstrate poor speech discrimination long term? Abnormal PEACH at 20 months CAEPs prompted appropriate recommendation to review fitting & management. 5 abnormal PEACH or IT-MAIS 1 inconsistent functional audibility results (normal PEACH at 7 mths but abnormal IT-MAIS at 13 mths. One ear 80 dBHL) NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Auditory Neuropathy case study NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Electrocochleography - ECochG A ‘Golf Club’ electrode is placed in the round window niche of the cochlear. NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM ECochG in ANSD cases Normal Hearing Normal responses can be seen right down to soft levels. 90dB 30dB 80dB 70dB 60dB 50dB 40dB 20dB ANSD Abnormal Positive Potentials An unusual positively shaped peak is seen at high & moderate intensities. NAL: Dillon, Van Dun, Carter, Gardner-Berry

WP ASA 2004 250 500 750 1000 1500 2000 3000 4000 6000 8000 0 10 20 30 40 50 60 70 80 90 100 110 HEARING LEVELS IN DECIBELS FREQUENCY (Hz) Case Study 2 ABR 28/8/03 - NR ABR (CM only) ABR (CM only) NAL: Dillon, Van Dun, Carter, Gardner-Berry

WP ASA 2004 250 500 750 1000 1500 2000 3000 4000 6000 8000 0 10 20 30 40 50 60 70 80 90 100 110 HEARING LEVELS IN DECIBELS FREQUENCY (Hz) Case Study 2 ABR 28/8/03 - NR CAEP 14/10/03 m g t m g t ABR (CM only) ABR (CM only) NAL: Dillon, Van Dun, Carter, Gardner-Berry

WP ASA 2004 250 500 750 1000 1500 2000 3000 4000 6000 8000 0 10 20 30 40 50 60 70 80 90 100 110 HEARING LEVELS IN DECIBELS FREQUENCY (Hz) Case Study 2 ABR 28/8/03 - NR 15/3/04 - NR CAEP 14/10/03 30/3/04 ECochG 15/3/04 ECochGECochGECochGECochG m g t m g t ABR (CM only) ABR (CM only) (abnormal potentials only) NAL: Dillon, Van Dun, Carter, Gardner-Berry

WP ASA 2004 250 500 750 1000 1500 2000 3000 4000 6000 8000 0 10 20 30 40 50 60 70 80 90 100 110 HEARING LEVELS IN DECIBELS FREQUENCY (Hz) Case Study 2 ABR 28/8/03 - NR 15/3/04 - NR CAEP 14/10/03 30/3/04 ECochG 15/3/04 VROA 29/4/04 m g t m g t ECochGECochGECochGECochG ABR (CM only) ABR (CM only) (abnormal potentials only) NAL: Dillon, Van Dun, Carter, Gardner-Berry

What we currently understand & are building on Future Directions We plan to follow these babies up so we can perform more detailed assessments on speech discrimination ability in quiet and noise. These results will be compared to both their CAEP and ECochG responses to see if predictive patterns can be seen. Present CAEPs are present for at least 2 out of 3 speech stimuli. Continue with current management & continue to monitor closely Absent CAEPs are absent for at least 2 out of 3 speech stimuli. Current management path should be reviewed immediately. Consider gain adjustments and/or potential problems with speech discrimination even when sounds are audible. I SEE! NAL: Dillon, Van Dun, Carter, Gardner-Berry

creating sound value TM Conclusions 1.Predict audibility of speech sounds - is 4FA on PTA: <80 dBHL (hearing aid range) >80 dBHL (cochlear implant range) 2. Predict whether auditory function is significantly affected (with the view to look at speech discrimination ability in the future) 1.For the 8 subjects whose audibility of the speech stimuli was <=25 dB (either under-fitted or outside of the aidable range): all showed no CAEP response for at least 2/3 stimuli? 2.For the 6 subjects whose audibility of the speech stimuli was >25 dB: 3 subjects showed present CAEP responses for at least 2/3 stimuli. 3 subjects showed absent CAEP responses to at least 2/3 stimuli. Preliminary signs of good auditory functional ability Preliminary signs of poor auditory functional ability Preliminary signs of poor/inconsistent auditory functional ability OVERALL: Combining CAEPs with PEACH/IT-MAIS may help to highlight those who need to have their audiological & intervention management reviewed ASAP. NAL: Dillon, Van Dun, Carter, Gardner-Berry

Some cortical response measurements not ready for clinical use yet To summary To summary NAL: Dillon, Van Dun, Carter, Gardner-Berry

/Ah/ 2 second duration ms -350.0150.0650.01150.01650.02150.02650.0 µV 0.0 2.5 5.0 -2.5 -5.0 -7.5 Onset Gap Offset 0msG.avg 50msG.avg 10msG.avg 20msG.avg 5msG.avg Kirsty Gardner-Berry NAL: Dillon, Van Dun, Carter, Gardner-Berry

N1 and P2 cortical amplitudes for /a/ in noise are enhanced when 700 s inter-ear delay is introduced to noise in normal listeners (N=8, 19-32 years) Indicator of binaural functioning NAL: Dillon, Van Dun, Carter, Gardner-Berry

Size of the electrophysiological “unmasking” effect is correlated with behavioral MLD (speech detection threshold) at -10 dB SNR r=-.76, p=.028 NAL: Dillon, Van Dun, Carter, Gardner-Berry

Summary Cortical responses –Evaluate the audibility of speech sounds –Indicate the maturity of the auditory system –Estimate hearing thresholds when the patient is awake (adults) –Automatic detection as good as experts –Residual noise size critical NAL: Dillon, Van Dun, Carter, Gardner-Berry

Thanks for listening www.nal.gov.au NAL: Dillon, Van Dun, Carter, Gardner-Berry

The HEARing CRC Member Organisations This research was financially supported by the HEARing CRC established and supported under the Australian Government’s Cooperative Research Centres Program NAL: Dillon, Van Dun, Carter, Gardner-Berry

Title First fitting NAL: Dillon, Van Dun, Carter, Gardner-Berry

Title 2 nd fitting NAL: Dillon, Van Dun, Carter, Gardner-Berry

Title 3 rd at 65 NAL: Dillon, Van Dun, Carter, Gardner-Berry

Title 3 rd at 55 NAL: Dillon, Van Dun, Carter, Gardner-Berry

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

Evaluating speech detection in aided infants and estimating pure tone thresholds in unresponsive adults: Auditory-evoked cortical potentials Harvey Dillon,

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Evaluating speech detection in aided infants and estimating pure tone thresholds in unresponsive adults: Auditory-evoked cortical potentials Harvey Dillon,

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Presentation on theme: "Evaluating speech detection in aided infants and estimating pure tone thresholds in unresponsive adults: Auditory-evoked cortical potentials Harvey Dillon,"— Presentation transcript:

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