Auditory processing disorder (APD) and specific language impairment
Auditory processing disorder (APD) and language impairment Dorothy V M Bishop
A diagnostic puzzle• Child reports listening problems but passes hearing test• A common complaint: difficulties hearing speech in noisy situations• Two possibilities: 1. Auditory problems caused by higher level brain abnormalities 2. Problem is not auditory at allMoore, D. R., Rosen, S., Bamiou, D.-E., Campbell, N. G., & Sirimanna, T. (2012).Evolving concepts of developmental auditory processing disorder (APD): A BritishSociety of Audiology APD Special Interest Group ‘white paper’. International Journal ofAudiology, (e print). doi: 10.3109/14992027.2012.723143
Option #1• Auditory problems are caused by higher level brain abnormalities• This corresponds to idea of Auditory Processing Disorder, or APD
Higher-level auditory processing• Hearing test assesses ability to detect sounds – Picks up problems in pathways from ear to auditory nerve (peripheral hearing)• Beyond auditory nerve, auditory information processed in complex set of pathways• Information about sound features such as pitch, loudness, duration, spatial location, is extracted• In adults, damage to higher auditory pathways can produce problems recognising sounds
Auditory processing disorder in children• Audiologist assesses skills such as ability to: – combine information from both ears – identify speech in noisy background – understand speech if some auditory cues removed• If these skills are impaired, this could indicate a problem with central auditory pathways
Three problems• Accurate assessment requires good information on how children of different ages perform on auditory tests – not always available – E.g. Widely-used SCAN tests not suitable in UK – British children score low because don’t understand US accent• Most tests unsuitable for children below 7 yr old• Poor performance on auditory tests can arise for reasons other than auditory problem, e.g. limited language ability, poor attentional skillsDawes, P., & Bishop, D. V. M. (2007). The SCAN-C in testing for auditory processing disorder in asample of British children. International Journal of Audiology., 46, 780 - 786.
Option #2• Auditory problems are not primary.• Difficulties with auditory tests arise because of limitations of attention, memory or language.Loo, J. H. Y., Bamiou, D.-E., & Rosen, S. (2012). The impacts of language backgroundand language-related disorders in auditory processing assessment. Journal of Speech,Language and Hearing Research, 1092-4388_2012_1011-0068. doi: 10.1044/1092-4388(2012/11-0068)
Many children with poor language or literacy do poorly on APD tests• Could mean their language/literacy problems are caused by auditory difficulties• But could mean that the tests are misleading, and children fail because they have problems recognising or remembering words in difficult listening conditions• Concern among experts that audiologists are diagnosing APD in children that others would diagnose with dyslexia or SLIDawes, P., & Bishop, D. (2010). Psychometric profile of children with auditory processing disorder(APD) and children with dyslexia. Archives of Disease in Childhood, 95, 432-436.Ferguson, M. A., Hall, R. L., Riley, A., & Moore, D. R. (2011). Communication, listening, cognitiveand speech perception skills in children with auditory processing disorder (APD) or specificlanguage impairment (SLI). Journal of Speech Language and Hearing Research, 54(1), 211-227.doi: 10.1044/1092-4388(2010/09-0167)
Does it matter? Auditory Poor processing language#1 disorder skills Poor Impaired language performance#2 skills on APD tests Yes! Important implications for treatment
Key question• Where a child with language problems does poorly on APD tests, should we focus on training language skills or auditory skills? Bottom line: what is the most effective intervention?• In general, we don’t know because adequate studies have not been done• Experimental studies of training of auditory skills typically find you can improve performance but the training effect doesn’t generalise to other skillsHalliday, L. F., Taylor, J. L., Millward, K. E., & Moore, D. R. (2012). Lack ofgeneralization of auditory learning in typically developing children. Journal of Speech,Language and Hearing Research, 55(1), 168-181. doi: 10.1044/1092-4388(2011/09-
Interventions for APD• British Society for Audiology guidelines: – Reviews of different interventions for APD, noting whether there is any good evidence for themBritish Society of Audiology. (2011). An overview of current management of auditoryprocessing disorder (APD).http://www.thebsa.org.uk/images/stories/docs/BSA_APD_Management_1Aug11_FINAL_amended17Oct11.pdf.
Assistive listening FM devices• E.g. wireless devices that amplify distant auditory input (such as teacher voice) and deliver to the ear of the listener. BSA noted numerous studies but “Strong evidence supporting use of personal FM systems for APD intervention was not found.” Also, studies typically funded by manufacturers who have financial interest. Need for well-designed, independent, randomised controlled trials.
Computerised training: FastForword• Intensive training programme designed for children with specific language impairment.• Aims to train ability to perceive brief and transient aspects of sound signals.• Initial reports encouraging, but later independent randomised controlled trials on children with SLI failed to show any difference from controlsStrong, G. K., Torgerson, C. J., Torgerson, D., & Hulme, C. (2010). A systematic meta-analytic review of evidence for the effectiveness of the ‘Fast ForWord’ languageintervention program. Journal of Child Psychology and Psychiatry, 52(3), 224-235. doi:10.1111/j.1469-7610.2010.02329.x
Computerised training: specific applications to children with APD• Review by Loo et al (2010), looking at computerised interventions including FastForword and Earobics.• Phonological awareness skills, which are specifically trained, improved, but not much generalisation to other skills.• Conclusion: insufficient evidence: randomised control studies are necessaryLoo, J. H. Y., Bamiou, D.-E., Campbell, N., & Luxon, L. M. (2010). Computer-basedauditory training (CBAT): benefits for children with language- and reading-relatedlearning difficulties. Developmental Medicine and Child Neurology, 52(8), 708-717.
Computerised training: LiSN and Learn Auditory Training Software• Specifically designed to remediate spatial processing problems in children with APD, i.e. problems with sound source location cues• Training for 15 mins per day for 12 weeks• Randomised controlled trial. Results promising but small sample size, 2/7 children dropped out, and limited data analysis• No evidence of generalisation to improved language skills• Need for larger, independent, randomised controlled trials looking at wider range of outcomesCameron, S., & Dillon, H. (2011). Development and evaluation of the LiSN & Learnauditory training software for deficit-specific remediation of binaural processing deficits inchildren: Preliminary findings. Journal of the American Academy of Audiology, 22(10),678-696. doi: 10.3766/jaaa.22.10.6
Auditory integration therapy (AIT)• This and similar treatments not recommended by BSA because little or no evidence of efficacy and conflicting expert opinion.• Also ethical and safety issues raised in the USA – Position statement by American Speech-Language Hearing Association: – http://www.asha.org/docs/html/TR2004-00260.html
Conclusions: Interventions for APD• Most APD treatments either have only anecdotal evidence in support, or uncontrolled studies.• For explanation of why controls are essential, see: http://deevybee.blogspot.co.uk/2010/08/three-ways-to- improve-cognitive-test.html• Also concern if only evidence comes from those with financial interests in the intervention• Urgent need for better research looking at impact on language and literacy skills
Overall conclusion• Most children presenting with auditory symptoms will have broader problems with language, literacy, attention, or social interaction• Children who present with language problems may have hidden auditory problems• Important to have multidisciplinary assessment to ensure children get full diagnosis and appropriate recommendations for interventionWitton, C. (2010). Childhood auditory processing disorder as a developmental disorder:The case for a multi-professional approach to diagnosis and management. InternationalJournal of Audiology, 49(2), 83-87. doi: 10.3109/14992020903289808