The Difference Between Auditory Processing Disorder and Specific Language Impairment
Ferguson et al (2011) examined 19 normal hearing children who were diagnosed as having auditory processing disorders (APDs) and compared them to 22 children diagnosed with specific language impairment (SLI) and compared those two groups to 47 mainstreamed (MS) children. The goal was to see if there were differences among these three groups of children with respect to measures of intelligence, language, memory, language, phonology, literacy, and speech intelligibility.
Ferguson et al note that after decades of studying APD, there is no consensus with regard to what APD is, the diagnostic markers, assessment or management of APD. They note that there exists a lack of agreement as to a "gold standard" APD diagnostic test, which has led to use of a plethora of "unvalidated tests."
The authors note that despite the two different clinical diagnosis, the APD and SLI groups of children performed similarly on these multiple measures and both groups (APD & SLI) were consistently outperformed by the mainstream (MS) group of children. Importantly, Ferguson et al stated that their results suggest "the children were differentially diagnosed based on their referral route rather than on actual differences" and despite the very common account/claim of listening in noise difficulties for children with APD, this account/claim was not supported by their test results.
Indeed, the authors state that "the clinical groups (APD and SLI) performed no more poorly than the MS (mainstream) group, either in quiet or in noise." The authors suggest poor attention may be the basis of previously reported listening difficulties. Further, they suggest APD and SLI may be indistinguishable.
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.
Ferguson, M. (2009): Diagnosing Auditory Processing Disorders. ENT News, In Audiology Matters. February 2009.
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.
Moore DR. (2006) Auditory Processing Disorder (APD): Definition, Diagnosis, Neural basis and Intervention. Audiolgical Medicine l (4):4-11.