APD and Diagnostic Criteria Variability
Wilson and Arnott (2013) state, "There remains no universally accepted set of diagnostic criteria for central auditory processing disorder (APD)." Wilson and Arnott report that ASHA (2005) stated the diagnosis of APD generally depends on poor performance being recorded 2 standard deviations (or more) below the mean, on two or more tests (within the APD battery), whereas the Academy (2010) stated that APD can be diagnosed when scores are two standard deviations (or more) below the mean for at least one ear, on two APD tests. The British Society of Audiology (BSA) (2011) did not specifically state diagnostic criteria for APD. Rather, BSA stated APD is characterized by poor perception of speech and non-speech sounds, indicating two tests would need to be failed for the diagnosis "APD" to be applied—one based on speech sounds, and the other not based on speech sounds.
Wilson and Arnott performed a retrospective analysis of 150 children with normal hearing, who ranged in age from approximately 7 to 15.5 years. Each of the children completed an APD test assessment, which included low-pass filtered speech, two-pair dichotic digits, competing sentences and frequency patterns with linguistic or non-linguistic report (30 sequences of three tones, each). Each child was evaluated and diagnosed based on each of the three (Academy, ASHA, BSA) criteria, and six other published criteria including Bellis (2003), Dawes and Bishop (2009), and McArthur, (2009, see article for additional details).
Based on the most lenient to the strictest criteria, APD diagnosis for the children would have been from 7 percent to 96 percent (respectively), depending on which criteria and tools were used. Due to the high variability and the vast range of possible APD diagnosis, Wilson and Arnott recommend whenever a child is diagnosed with APD, an explicit statement of the criteria used to diagnose APD should be clearly stated. Further, they state "calls to abandon the use of APD as a global label should be supported."
For More Information, References, and Recommendations
Cox LC, McCoy SL, Tun PA, Wingfield A. (2008): Monotic Auditory Processing Disorder Tests in the Older Adult Population. Journal of the American Academy of Audiology 19:293–208.
Dawes P. (2011) The SCAN-A in Testing for Auditory Processing Disorder in a Sample of British Adults. International Journal of Audiology 50:107–111.
Dillon H, Cameron S, Glyde H, Wilson W, Tomlin D. (2012) An Opinion on the Assessment of People Who May Have an Auditory Processing Disorder. Journal of the American Academy of Audiology 23:97–105.
Ferguson MA, Hall RL, Riley A, Moore DR. (2011) Communication, Listening, Cognitive, and Speech Perception Skills in Children With Auditory Processing Disorder (APD) or Specific Language Impairment (SLI). Journal of Speech, Language and Hearing Research 54 (2):211–227.
Kreisman NV, John AB, Kreisman BM, Hall JW, Crandell CC. (2012) Psychosocial Status of Children with Auditory Processing Disorder. Journal of the American Academy of Audiology 23:222-233.
Sharma M, Purdy SC, Kelly AS. (2012) A Randomized Control Trial of Interventions in School-Aged Children with Auditory Processing Disorders. International Journal of Audiology 51:506–518.
Wilson WJ, Arnott W. (2013) Using Different Criteria to Diagnose Central Auditory Processing Disorder – How Big a Difference Does it Make? Journal of Speech, Language and Hearing Research 56:63-70.