Author: Emilie May Yan Lam
Lam, Emilie May Yan, 2015 Intervention for Children with Auditory Processing Disorder (APD): The Effectiveness of Bottom-Up and Top-Down Interventions, Flinders University, School of Health Sciences
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The current recommendation for interventions for Auditory Processing Disorder (APD) is that they should involve both 'bottom-up' interventions that target specific auditory processing (AP) deficits and 'top-down' interventions targeting other cognitive abilities (e.g., language and reading) that might be impeded (ASHA, 2005; BSA, 2011b; Chermak, 1999; Chermak, & Musiek, 2007). To date, empirical research in this area is limited. The current thesis sought to investigate this recommendation empirically through two studies concerning a prominent AP ability, namely frequency discrimination (FD). STUDY 1 aimed to investigate whether children with APD who also demonstrated FD difficulty would have poorer reading, language, auditory-sustained attention, and executive control than children with APD who had age-appropriate FD. Sixteen children with APD (aged 7;5 to 10;6), eight with FD difficulty (FD-DIFF group), and eight with age-appropriate FD (FD-WNL group) were tested for word reading, phonological processing (PP) (which included phonological awareness, phonological memory and rapid naming), language, auditory-sustained attention, and executive control. The FD-DIFF group showed significantly poorer non-word reading, regular word reading, and phonological awareness than the group with age appropriate FD. However, there were no group differences regarding irregular word reading, phonological memory, rapid naming, receptive language, auditory-sustained attention, and executive control. These findings suggest that FD seems to affect decoding skills that are required during reading, i.e., the non-lexical reading process in the dual route model of reading (Coltheart, Rastle, Perry, Langdon, & Zeigler, 2001), and is relatively independent of the lexical reading process, or sight word reading. Also, FD seems to be independent of language, attention, and executive control. STUDY 2 sought to investigate the outcomes of two intervention programs in children with APD, when administered in isolation or in combination. The interventions were: 1) a bottom-up intervention program to improve FD - the FD intervention (McArthur et al., 2008), and 2) a top-down intervention program to improve PP - the PP intervention (Rajkowski, 2003). An important focus of this study was to investigate whether prior FD intervention would enhance the outcome of the subsequent PP intervention. Generalisation of potential intervention effects of both intervention programs was also studied: 1) generalisation to another task that involved the same ability targeted during intervention, and 2) generalisation to overall language and reading abilities. Nineteen children with FD and PP difficulties (aged 7;5 years to 9;9 years), who were also diagnosed with APD, were randomly allocated to one of four groups: 1) a group that undertook six weeks of FD intervention followed by six weeks of PP intervention - the FD-PP group; 2) a group that undertook six weeks of visual discrimination intervention (VD intervention) followed by six weeks of PP intervention - the VD-PP group; 3) a group that undertook six weeks of PP intervention with no prior interventions -the PP group; and 4) a no-intervention control group - the CON group. The findings showed that FD intervention resulted in significant intervention-specific improvement. However, there was no generalisation to a similar task of FD, or to language and reading abilities. PP intervention also resulted in significant intervention-specific improvement. There was partial support for the generalisation to a similar PP task and non-word reading. However, there was no generalisation to regular word reading, irregular word reading and language comprehension. Interestingly, when combined with prior FD intervention, significant generalisation of the PP intervention effect was observed for phonological awareness, non-word, and regular word reading. Therefore, the results demonstrate that prior FD intervention had enhanced the PP intervention outcome for the measures that are related to the non-lexical reading process. In conclusion, the present findings support the assertion that FD might affect the non-lexical reading process. Prior remediation of FD difficulty could enhance the effect of subsequent reading-related interventions for non-lexical reading. These findings support the recommendation that interventions for APD should incorporate both bottom-up and top-down interventions.
Keywords: auditory processing disorder,auditory perceptual disorder,central auditory processing disorder,frequency discrimination,reading,therapy for auditory processing disorder,intervention for auditory processing disorder,management of auditory processing disorder
Subject: Health Sciences thesis
Thesis type: Doctor of Philosophy
School: School of Health Sciences
Supervisor: Dr. Willem van Steenbrugge, Dr. Christopher Lind, Dr. Sarosh Kapadia