Auditory Processing Disorders: Development and Standardization of SCAN-3 Tests for Auditory Processing Disorders Robert W. Keith Ph.D. Educational Audiology Summer Conference Monday June 20, 2009
Does this describe your reaction when you consider the literature on assessment and remediation of APD?
Is this your response when you are asked to do an APD evaluation and make recommendations for remediation?
Do you just want to retreat to your own comfortable world, and forget that APD exists?
Well join the crowd - you are part of a large group of professionals! Let’s examine together some of the concepts related to APD and then talk about the SCAN revision!!
Central Auditory ProcessesResponsible for the following Phenomenon (ASHA, 1996) • Sound localization and lateralization • Auditory discrimination • Auditory pattern recognition • Temporal aspects of audition -Temporal resolution -Temporal masking -Temporal ordering • Performance with competing signals • Performance with degraded signals • “These mechanisms and processes are presumed to apply to nonverbalas well as verbal signals … they have neurophysiologic as well as behavioral correlates.”
ASHA (1996) Consensus Conference Definition of CAPD • Dysfunction of processes dedicated to audition • General dysfunction of attention or neural timing • Co-existing
The Importance of Modality Specificityin Diagnosing Central AuditoryProcessing Disorder Central Auditory Processing Disorder in School-Aged Children: A Critical Review Anthony T. Cacace and Dennis J. McFarland Journal of Speech, Language, and Hearing Research Vol.41 355-373 April 1998.
Anthony T. Cacace and Dennis J. McFarland • Purpose: This article argues for the use ofmodality specificity as a unifying framework bywhich to conceptualize and diagnose centralauditory processing disorder (CAPD). The intentis to generate dialogue and critical discussionin this area of study.Method: Research in the cognitive, behavioral,and neural sciences that relates to the conceptof modality specificity was reviewed andsynthesized.
Report of the Consensus Conference on the Diagnosis of APD in School- Aged ChildrenJerger and MusiekJAAA 11:467-474, 2000
Report of the Consensus Conference on the Diagnosis of APD in School- Aged ChildrenJerger and Musiek JAAA 11:467-474, 2000 An auditory processing disorder (APD) is defined as a deficit in the processing of information in the auditory modality.
Consensus Conference on the Diagnosisof APD in School-Aged Children: Minimal APD Test Battery • Behavioral measures • Pure tone audiometry • P-I functions for word recognition • Dichotic task (digits, words, and/or sentences) • Duration pattern sequence test • Temporal gap detection • Electrophysiologic measures • Immittanceaudiometry • Otoacoustic emissions • ABR • MLR • P300 (optional)
Consensus Conference on the Diagnosisof APD in School-Aged Children: Optional Procedures • To demonstrate the processing disorder is auditory specific –compare performance on analogous auditory and visual tasks, e.g. • Continuous performance tasks • P-300
The Controversy: Clinical and Research Concerns Regarding the 2000 APD Consensus Report and Recommendations Katz, Johnson, Brandner, Delgrange, Ferre, King, Kossover-Wechter, Lucker, Medwetsky, Saul, Rosenberg, Stecker, Tillery Audiology Today March/April 2002 Volume 14 Number 2 2002
Clinical and Research Concerns: Philosophy • APD requires an educational model rather than a diagnosis model • Diagnosing APD versus describing behavior that promotes seeking remedies • Insufficient research to document statements, cannot tell what is opinion • Research on adults with lesions not appropriate to APD in children
Physiologic Measures OAE ABR MLR Behavioral Measures PI-PB Dichotic Digits Duration Patterns Temporal Gap Detection Clinical and Research Concerns: Professional Tests recommended as minimal test battery do not meet acceptable pschoacoustic standards.
The Response: On the Diagnosis of Auditory Processing Disorder – a reply Jerger and Musiek Audiology Today Volume 14, Number 2 2002
The Jerger and Musiek Reply • Disentangle diagnosis from treatment • Disentangle APD from other problems such as attentional and linguistic factors • Different approaches to diagnosis have unique advantages and disadvantages • The diagnosis of APD lacks a gold standard • Electrophysiological and electroacoustic measures are central to the diagnosis of APD • There is time. You just have to take it.
American Speech-Language-Hearing Association. (2005). (Central) Auditory Processing Disorders [Technical Report]. Available from www.asha.org/policy. The charge to the Working Group on Auditory Processing Disorders was to review the ASHA technical report, “Central Auditory Processing: Current Status of Research and Implications for Clinical Practice” (ASHA, 1996) and determine the best format for updating the topic for the membership.
American Speech-Language-Hearing Association. (2005). (Central) Auditory Processing Disorders [Technical Report]. Available from www.asha.org/policy. • References the Bruton conference and the modality-specific nature of (C)APD and its differential diagnosis • “modality-specificity” as a diagnostic criterion for (C)APD is not consistent with how processing actually occurs in the CNS.” • “Any definition of (C)APD that specifies complete modality-specificity as a diagnostic criterion is neurophysiologically untenable.”
American Speech-Language-Hearing Association. (2005). (Central) Auditory Processing Disorders [Technical Report]. Available from www.asha.org/policy. • Individuals with (C)APD exhibit sensory processing deficits that are more pronounced in the auditory modality and, in some individuals, auditory-modality-specific effects may be demonstrated (Cacace & McFarland, 1998).
American Speech-Language-Hearing Association. (2005). (Central) Auditory Processing Disorders [Technical Report]. Available from www.asha.org/policy. • Although efforts continue to develop more sensitive behavioral tests of central auditory function, electrophysiologic, electroacoustic, and neuroimaging procedures may soon transform clinical auditory processing test batteries
Diagnosis of APD can be made only by the audiologist • (C)APD screening can be conducted by audiologists, SLPs, psychologists, and others using a variety of measures that evaluate auditory-related skills. • (C)APD is an auditory deficit; therefore, the audiologist is the professional who diagnoses (C)APD (ASHA, 2002a, 2004b). . . . . • The SLP's role in (C)APD focuses on “collaborating in the assessment of (central) auditory processing disorders and providing intervention (ASHA, 2001, p. 5).
On the Diagnosis of Auditory Processing Disorder (APD)JAAA Editorial by J. JergerJAAA Vol 20, No 3, March 2009 • “Tests for APD must by “simple, quick, cheap, easily scored” • Many normal symptom free children diagnosed with APD • Tests are plagued by nonauditory factors • Substantial recent work with fMRI, MEG, CT, EEG, EP • “Behavioral tests should be eschewed in favor of a systematic clinical research thrust to exploit contemporary technological advances in the search to identify and understand this troubling disorder”
CAPD – Two Divergent Approaches • Medical – Site of Lesion • Educational – Auditory,Language, Reading and Learning Disorders
What is an adequate method of interpreting AP test results? • Determine auditory test standard scores including percentile ranks and confidence intervals • Determine ear differences • Determine atypical or abnormal auditory processing abilities • Develop standard score profile for tests of • Intelligence • Language • Auditory Processing • Determine primary deficit or co-morbidity
Standard Scores • Compare a subject’s score between standardized tests • Compare a subject’s score to a previous score obtained on the same test • Compare a subject’s performance to a peer of the same age
Composite Standard Scores and Their Corresponding Distances from the Mean and Percentile Ranks Composite Distance from Percentile Standard Score the Mean Rank 145 +3 S.D. 100 130 +2 S.D. 98 115 +1 S.D. 84 100 Mean 50 85 -1 S.D. 16 70 -2 S.D. 2 55 -3 S.D. 0 For composite scores the mean = 100 and SD = 15
Subtest Standard Scores and Their Corresponding Distances from the Mean and Percentile Ranks Subtest Distance from Percentile Standard Score the Mean Rank 19 +3 S.D. 100 16 +2 S.D. 98 13 +1 S.D. 84 10 Mean 50 7 -1 S.D. 16 4 -2 S.D. 2 1 -3 S.D. 0 For subtest scores the mean = 10 and one SD = 3
Guidelines for Interpreting Children’s Performance on SCAN-C Based on Subtest and Composite Standard Scores Subtest Composite Auditory Standard Standard Processing Score Score Performance 7 or above 85 or above Normal 4 to 6 70 to 84 Borderline below 3 below 69 Disordered
Age equivalent scores Age/Grade Equivalent scores. Some tests provide age or grade equivalent scores. Such scores indicate that the student has attained the same score (not skills) as an average student of that age or grade. For example, if Sally obtains a grade-equivalent score of 3.6 on a reading comprehension test, this means that she obtained the same score as the typical student in the sixth month of third grade. Sally may or may not have acquired the same skills as the typical third grader. Age/grade scores seem to be easy to understand but are often misunderstood, and many educators discourage their use.
Development and standardization of SCAN: the grandfather of the SCAN test battery family • Jack Willeford – 1974 • SCAN background research – literature and student research • Proposal to Tom Hutchinson ASHA 1983 • To develop a well standardized test of auditory processing that could be administered easily with simple equipment in the schools. The subtests included: • FW • AFG • CW • Binaural Fusion – omitted following standardization study • Standardization – 1035 children • SCAN: A screening test for auditory processing disorders in children - 1986 • SCAN: A Screening Test for Auditory Processing Disorders in Children, R.W. Keith. San Antonio: Psychological Corporation, 1986.
SCAN (Keith, 1986) • Subtests: • Filtered Words - low-pass at 1000 Hz • Auditory Figure-Ground at +8 dB S/N ratio • Competing Words (25 word pairs each, RE & LE) • Binaural Fusion eliminated (beta testing found no difference in performance between children with and without APD) • Standardization sample: • N = 1034 • 3:0 years to 10:11 years
SCAN-C: Test for Auditory Processing Disorders in Children – Revised (2000) The next generation SCAN
SCAN-C STANDARDIZATION PROTOCOL • 5-11 years • Normal Hearing • Normal Tympanometry • Regular classroom • Native English speaker
SCAN-C – number of subjects • Standardization N = 600 • Test - retest N = 150 • Construct validity N = 160 • Reliability N = 100 (SCAN had 1035 subjects in the standardization study)
Number of SCAN-C Subjects by Age Age (yrs & mos) n % of Sample 5.0 - 5.11 100 15.4 6.0 - 6.11 100 15.4 7.0 - 7.11 100 15.4 8.0 - 8.11 100 15.4 9.0 - 9.11 100 15.4 10.0 - 11.11 150 23.1 Total 650 100
SCAN-C Subjects by Gender Gender n% of Sample Female 317 48.8 Male 333 51.2 Total 650 100.0
SCAN-C Subjects by Race/Ethnicity Race n % of Sample African American 102 15.7 Hispanic 99 15.2 Other 28 4.3 White 421 64.8 Total 650 100.0
SCAN-C Sample by Geographic Region % of % of Region n Sample US Population Northeast 115 17.7 21.5 North Central 58 24.3 23.4 South 38 36.6 31.1 West 139 21.4 24 Total 650 100.0 100.0
SCAN-C MISCELLANEOUS • Subjects travel paid • 225 paid examiners, SLP & Audiologists • Data collected from schools, clinics & private practice • Data analysis by TPC • Test available on CD
SCAN-C Mean and SD of Standard Score Differences for the Matched Sample of Males and Females
Correlations Between the SCAN-C and SCAN Subtest and Composite Standard Scores SCAN-C FW AFG CW CS Comp FW 0.55 0.40 0.38 0.19 0.51 AFG 0.34 0.31 0.38 0.30 0.45 CW 0.62 0.33 0.72 0.50 0.75 Comp 0.68 0.41 0.72 0.48 0.79 SCAN
Ear Advantage Mean Score Between Children With CAPD and Children Without CAPD Right-Ear First Left-Ear First Age n Mean EA Mean EA Normal CAPD Normal CAPD 6 18 2.6 3.8 1.4 2.7 7 19 2.3 3.8 2.0 1.1 8 30 4.8 5.1 1.2 -1.6* 9 33 2.9 5.5* 1.3 -2.9** 10-11 44 2.3 6.9** 0.9 -3.8** * p<.05 **p<.01
SCAN-C Filtered Words 37 % Correct 32 27 22 5 6 7 8 9 10 & AGE (Years) 11