Dissertation Proposal

Speech Discrimination and Spatial Hearing in Toddlers with Cochlear Implants

Christi Hess, Ph.D CCC-SLPCI Day with the ExpertsMay 31, 2014

Binaural Hearing and Speech Laboratory WAISMANCENTER

Where we are Access to sound

Age of implantation

Bilateral cochlear implants (BiCIs)

Body of research and clinical knowledge that CIs provide access to sound for individuals with severe-profound hearing loss.Age of implantation has continued to decrease. Age of implantation effects for language development. Generally, both research and clinical practice has been to track language development using standardized tests. In the past 5-10 years, Bilateral cochlear implants (BiCIs) have become the standard of care. They have been shown to promote the development of spatial hearing skills in older children and adults

3Where we want to beUnderstanding the impact of early BiCIs on:

Language development

Fine-tuned auditory abilities

Spatial hearing???but little is known about the role of bilateral stimulation in enhancing language, fine-grained speech discrimination, and spatial hearing in infants and toddlers with CIs.

FINE-TUNED: HARD TO TEST, we give standardized tests, but difficult to test fine-grained auditory abilities important for word and language learning SPATIAL HEARING: tests have been done on older children with CIs showing benefit of BiCI but no research on children under 4LANGUAGE DEVELOPMENT: Have standardized test results in this population- research has tracked language skills of older children with UNILATERAL CIs

4This is what we can do now

Reaching for Sound

Litovsky, Ehlers, Hess & Harris, 2013Based on reaching in the dark studies, adapted paradigm to reaching for sound Has been shown to be successful for testing localization in toddlers with CIsNow, adapted it for speech discriminationExplain paradigm, reinforcement, show schematic- THEY LOVE IT! Collect a minimum of 72 trials from each toddler and testing sessions last up to two hours (with breaks)

Now we have a new tool to answer questions that have been elusiveWhat are some good questions?Here are the questions

5Stimuli

VoicingPlaceMannerEasy Value (ms)Hard Value (ms)BEEVoicedBilabialStop5 ms15 msPEAVoicelessBilabialStop45 ms35 msKEYVoicelessVelarStop45 msN/AInterested in the auditory abilities that these contrasts rely on. Not interested in the specific contrasts themselves- rather using them as a way to tell us what cues the auditory system is relying on.

Voicing Cue: Temporal information. The length of time between the release of the stop consonant and the beginning of vocal fold vibration is known as voice onset time (VOT). Along a continuum, a clear /b/ is located at the peak of one curve, and a clear /p/ is located at the top of other. In the middle of this continuum (~25ms) , there is an identification boundary. NH 1 month old infants can discriminate /b/ from /p/.Place Cue: Not going to get into the details, but should recall that it is a frequency or spectral cue. NH infants can discriminate place cues in their native language between 6-12 months.

6Participants13 toddlers with NH:Mean age: 31.8 mo. (8 Male, 5 Female)No history of hearing loss, ear infections, or other developmental delaysTymps and hearing screening performed

13 toddlers who use BiCIs:Mean age: 32.4 mo. (8 Male, 5 Female)At least 1 year of experience with CI1 at visitNative English speakerPrimary communication mode = oral/auralNo diagnosed developmental disabilitiesDid not control for: age of implant, device manufacturer, bilateral exp.28-37 mo. range7ProcedureLive-Voice FamiliarizationTraining (4/5 Criterion)Pea/Key vs. ByeTesting: (4 contrasts; 18 trials each) Place+VoicingPlaceVoicing(easy) Voicing(hard)

PlaceVoicing(hard)Place+Voicing Voicing(easy)

Familiarization: Before entering the sound booth, the child receives exposure to the words and pictures used in the study through a live-voice familiarization. The experimenter presents each picture card to the child, while saying the accompanying phrase. The experimenter then places one picture on a puppet show game, so that the child learns to reach for a hidden toy when he/she hears, Im hiding under (stimulus).

PLAY VIDEOS OF TRIAL TYPES ON THESE SLIDES

8NH are more accurate than BiCI

*p=0.03Look at the trends WITHIN the NH group:High percent correctSome toddlers at ceiling but not all, bc theyre 2-3Statistically differentMore variability on most difficult contrast

----- Meeting Notes (12/6/13 11:11) -----Check Bonferroni corrections (need 4?)

Criteria should be p=0.02 with

Effect sizes should be reported, too.

9

*p=0.04Want to compare to overall findings within BiCI group:Lower accuracy across the boardDifferent distributions of variabilityStatistically different Voicing contrasts

Spectral cues vs. Timing cues (VARIABILITY) more reliable cue, less reliability

Sig difference between Voicing (timing conditions)

10

11

****p=0.001p=0.002p=0.002p=0.002Spend a few min here!!

Significant Differences between groups in all 4 conditions

EXCITING RESULTS! SOME CI KIDS WITHIN SAME RANGE AS NH TODDLERS! WHY NOT ALL?? Can see variability in CI data. WHY?! Want to understand what could be different between this kid and this kid13

Even though all toddlers 28-37 months- no two toddlers are the same.

Explain each variable, talk about labeling of CI subjects1-13

Look at CI-5,

Compare to CI-11

Want to see if these two performed differently on the task.14

X-AXIS: age of visitY-AXIS: Combined performance on all 4 contrasts 15

*r2=0.32r2=0.08r2=0.07r2=0.005Talk about each graph:

Hearing age and bilateral expereince showing slight trend towards more= better performance, but with this few kids, impossible to tell because they are all clustered togetherTherapy --> again, small group of kids, only 4 with more than 4 hours/week. who is getting therapy? Kids that need it more? Also dont account for therapy setting some in a preschool for hearing impaired others via skype at home

CAUTIOUS in saying not significant because small group of toddlers

16

Look at all the data we have nowContrast-specific info, relationships to other demographic factors

Remind them where you started, how far youve come

17

18Quiet = IDEAL!

But, unrealistic

Wouldnt it be great to have something more realistic 20

Look at this girl here. She needs to listen to the adult, but theres all sorts of background noiseThere are a few things in her favor. He is located in a different direction compared to all the noisy kids, AND he has a different kind of voice, with different pitch, etcThese are cues that we KNOW older children can use. Do we think that toddlers with NH and cochlear implants can use these skills? We dont know. We think that toddlers can, but at the moment, only been shown clinically in 3+ year olds and nobody really knows what toddlers with CIs can do.Wouldnt it be great if we could extend our knowledge of NH and BiCI toddlers

Lets take a step towards finding out we cant understand every factor at once, but we can look at the use of location or spatial cues, since thats thought to be one of the benefits of listening with two ears. So, it makes sense that we should learn about this. 21Location Cues

22-=Spatial HearingWhen I use the term Spatial Hearing, I mean the ability to USE the location cues that our two ears are designed to use23CRISPGaradat & Litovsky, 2007We cant go test kids while theyre on a playground, and the reaching for sound paradigm described before wouldnt be useful for testing location cues, so we needed to use a DIFFERENT test.

Decided to use test that has been established for testing location cues that simulates what happens in the real world

Have this way to test this use of spatial cues in older children with NH and CIs, published results on 4-10 year olds with CIs

EXPLAIN CRISP and CRISP Jr.24Testing Conditions= Target (Male)

= Masker (2 Females)

QuietCollocatedSeparatedCRISPGaradat & Litovsky, 2007

StimuliTarget: male-talker, adaptive (starting 60 dB SPL)

Masker: 2 female talkers, fixed (55 dB SPL) Garadat & Litovsky, 2007Talk about using the same stimuli from published test27ProcedureFamiliarization with target words

Speech Reception Threshold (SRT) 80% correct criterion, calculated using a 3-down/1-up procedureTraining (4 trials)Quiet and Collocated conditions

Testing: 4-AFC task (repeated 2 times for each condition) QuietCollocatedSeparatedCollocatedSeparatedQuiet CollocatedQuietSeparatedQuietSeparatedCollocatedGaradat & Litovsky, 2007

Lower is better

Comparing collocated to separated SRT decreased (I.E. IMPROVED PERFORMANCE!)29

Better SRTs when masker is in a different location than the target

*

*

*

*

*

*

*

p