Auditory processing disorders, reading deficits and dichotic perception Sharon Cameron, Harvey Dillon, Kiri Mealings John Seymour, Jessica Whitfield, Taegan Young National Acoustic Laboratories CHSCOM2017 Linkoping July 2017 A talk in two parts Auditory processing disorders and reading Auditory processing Dichotic perception: what is being measured Reading deficit LiSN-S Spatial processing disorder LiSN & Learn Sound Storm ? Dichotic deficit Digit span forward and reverse Dichotic Digit Test Dichotic deficits Memory Memory Booster Wireless remote microphone Dichotic training ARIA, DIID Types of Reading Disorders: The Castles and Coltheart Test 2 (CC2) Deficits with words that must be learned by sight: Deficits with words that are learned by “sounding out”: • Unfamiliar regular words (ligneous) • Non-Words (lenk) • Irregular Words (yacht) Phonological Dyslexia (Sub-lexical route) 24%* < -1 SD applied Mixed Dyslexia Surface Dyslexia (Lexical route) 56%* 20%* McArthur et al., 2013 4 Hypotheses Auditory Deficit Phonological Dyslexia Speech sounds analysed with sufficient resolution: • • Rapid formant transitions (Tallal) Rise time and modulation detection (Goswami) Internal templates of these sounds become unclear, or “fuzzy”, potentially impacting letter-sound matching. Manifests behaviourally as: • poor categorical perception of plosive speech sounds (PIT), or • poor perception of syllable boundaries (ParSE). 5 Phoneme Identification Test (PIT) • Purpose: Measures the precision of categorical perception of stop consonants • Stimuli: 92 /ba/ and /da/ tokens. • Variation: F2 changes along an 11-step continuum from 100% /ba/ to 100% /da/. • Test Conditions: Quiet and Noise (0 dB SNR) • Response: Participant presses BA or DA button depending on what phoneme they heard. 6 /da/ responses (%) Typical PIT Results 100% /ba/ ILTASS Filtered White Noise 100% /da/ PIT “Ambiguous Region” – TD vs Phonological Dyslexia Typically Developing Child Child with Diagnosed Phonological Dyslexia 8 Parsing Syllable Envelopes (ParSE) Test 9 Typical ParSE Results UBUR: Upper Bound of the Uncertainty Region 0% AM 50% AM 100% AM ParSE “Ambiguous Region” – TD vs Phonological Dyslexia Typically Developing Child Child with Diagnosed Phonological Dyslexia 11 Results: 1. Normative data – Phoneme Identification Test Uncertainty region in quiet Uncertainty region in noise 12 Results: 2. Normative data – Parsing syllable envelope test 13 Results: 3. Relation to reading ability n=16! 14 Child with reported reading difficulties: What type? Test: CC2 Fail non-words Phonological dyslexia N=4 Auditory deficit? Test: PIT & ParSE Fail non-words and irregular words Auditory deficit? Mixed dyslexia Test: PIT & ParSE N=6 Auditory deficit Pass (≥ -1 SD): Other deficit Fail (<-1.67 SD): Auditory deficit Pass (≥ -1 SD): Other deficit Fail (<-1.67 SD): Fail irregular words Control Group Surface dyslexia Test: PIT & ParSE N=6 Fail (< -1.67 SD): Against hypothesis Pass (≥ -1 SD): As hypothesized n=4 n=0 5 Pit 3 Parse n=4 n=2 n=1* Parse n=4 15 Child with reported reading difficulties: What type? Test: CC2 Fail non-words Phonological dyslexia N=4 Auditory deficit? Test: PIT & ParSE Fail non-words and irregular words Auditory deficit? Mixed dyslexia Test: PIT & ParSE N=6 Auditory deficit Pass (≥ -1 SD): Other deficit Fail (<-1.67 SD): Auditory deficit Pass (≥ -1 SD): Other deficit Fail (<-1.67 SD): Fail irregular words Control Group Surface dyslexia Test: PIT & ParSE N=6 Fail (< -1.67 SD): Against hypothesis Pass (≥ -1 SD): As hypothesized n=4 Trial WRM n=0 n=4 Trial WRM n=2 n=1* n=4 16 Dichotic Testing What is it testing? National Acoustic Laboratories, Sydney, Australia Existing dichotic tests • Dichotic paradigms are the most commonly used tests in CAPD batteries. 1, 8 2, 4 • Intended to assess binaural interactions • Dichotic Digits Test (DDT) results correlate with academic outcomes and listening difficulty. 1, 2, 4, 8 18 Testing cognitive ability Dichotic tests • • • • • Selective attention Working memory Executive function Aging Mental Retardation Application to splitbrain patients Information about hemisphere differences Application to auditory processing disorder patients Inferences about auditory processing Cognitive deficits Brain “lesions” in Central Auditory Nervouse System Cause Indicate Low dichotic test scores National Acoustic Laboratories, Sydney, Australia The Dichotic Digits difference Test Cameron et al. (2016; JAAA) (DDdT) • Modified version of the DDT • Four different test paradigms: • Dichotic free recall • Dichotic directed left & right • Diotic • Computer scored • Norms based on exact age 22 National Acoustic Laboratories, Sydney, Australia Dichotic Free Recall Paradigm 2, 4 1, 8 1, 2, 4, 8 23 National Acoustic Laboratories, Sydney, Australia Diotic Paradigm 2, 4 1, 8 2, 4 1, 8 2,4,1,8 24 Interpreting results Diotic Recall Dichotic Free Recall Right ear advantage (free) 2, 4 2, 4, 1, 8 1, 8 2, 4, 1, 8 Dichotic advantage 1, 2, 4, 8 1, 2, 4, 8 Dichotic Directed Left Dichotic Directed Right 2, 4 1, 8 2, 4 1, 8 Right ear advantage (dir) 1, 8 2, 4 25 The participants Group N Digit span Attention TONI Life Fishers School W Typically developing 50 50 50 50 50 50 School S – Typically developing 62 - - - - - Adults – Typically developing 10 - - - - - CAPD clinics 103 children; 13 adults 116 93 9 10 - 10 Total 238 143 59 60 60 Clinic School 100 90 r = 0.82 80 Diotic (%) Dichotic versus diotic (%) 70 60 50 40 30 30 40 50 60 70 80 Dichotic free recall (%) 90 100 Directed right Free-recall right N=70 Free-recall left Directed left 28 2 1 Diotic (z score) Dichotic versus diotic (z score) Clinic School r = 0.78 0 -1 -2 -3 -4 -5 -5 -4 -3 -2 -1 0 Dichotic free recall (z score) 1 2 Correlations Attention (prudence) 0.26 Attention (vigilence) Forward digit span Reverse digit span 0.15 0.52 Diotic 0.42 0.24 Non-verbal IQ Correlations Attention (prudence) 0.31 Attention (vigilence) Forward digit span Reverse digit span 0.21 Free recall dichotic 0.53 0.36 0.27 Non-verbal IQ Correlations Attention (prudence) 0.22 Attention (vigilence) Forward digit span Reverse digit span 0.12 Directed dichotic 0.26 0.02 0.21 Non-verbal IQ 3 2 Dichotic free recall (z score) Dichotic scores and memory Clinic School 1 0 -1 -2 -3 -4 -5 -3 The normal range! -2 -1 0 1 2 3 Number memory forward (z score) 36 Multiple regression Diotic 0.70 Dichotic R = 0.80 R2 = 0.64 0.17 Forward digit span What about the other 36% of variance? Random measurement error Accounting for variance 9% 27% Dichotic test scores Memory 64% Other non-dichotic factors Dichotic factors 64% +27% 91% What about strong left-right asymmetries? An analogy Percent correct 100% 3 +4 ? 3,148 -1,659 ? 0% Cognitive resources applied to task An analogy Percent correct 100% Right Left 0% Cognitive resources applied to task National Acoustic Laboratories, Sydney, Australia Conclusions Scores on the commonly-used double-digit dichotic test are hugely influenced (~ 64% of variance) by abilities unrelated to dichotic perception. Measurement error accounts for ~ 27% of variance. Across the clinical and typically developing population studied, dichotic issues play a relatively small role (~ 9% of variance) in determining the scores obtained on these dichotic tests. What is the implication for how “dichotic deficits” should be remediated? 42 National Acoustic Laboratories, Sydney, Australia Support of the Australian Department of Health is greatly appreciated. www.NAL.gov.au 43 Effect of random measurement error 100% 90% 90% Example: R 80% 8 yr old: L=79%; R=88% 70% Observed score 70% L 60% 50% 40% 30% 20% asymmetry 20% 10% 0% 0% 10% 20% 30% 40% 50% True score 60% 70% 80% 90% 100% Dichotic deficit ≡ dichotic score – diotic score (normalised for age) Left Right Total Free recall dichotic 34% 25% Directed dichotic 65% 60% Diotic 29% 46% Dichotic advantge (z score) 4 Clinic School 3 2 1 0 -1 -2 -3 10 30 20 Age 50 40 70 60 80
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