Representing sounds and spellingsPhonological decline and compensatory working memory in acquired hearing impairment Pursue one great decisive aim with force and determination.Carl von Clausewitz "On war"
AbstractLong-term severe acquired hearing impairment (HI) is associated with a deterioration of phonological representations in semantic long-term memory that negatively affects phonological awareness (Andersson, 2002). The primary aim of this thesis was twofold: to use electrophysiological and behavioral measures to examine phonological processing in adults with moderate-to-profound, postlingually acquired HI, and to determine whether explicit working memory processing of phonology and individual working memory capacity (WMC) can compensate for phonological decline in this group. The secondary aim was to provide reference data for a Swedish test of WMC that is frequently used in the field of cognitive hearing science and to examine the relation between test performance and speech recognition in noise in a larger sample of individuals with HI.In papers I-III, non-auditory tasks were used to examine input and output phonological processing, episodic long-term memory, and WMC in individuals with HI as compared to a reference group with normal hearing. Text-based rhyme judgments of word pairs with matching or mismatching orthography and letter fluency were used to assess phonological processing. In papers II-III, the relation between phonological task performance and tests of WMC (papers II-III) and episodic long-term memory (paper II) were examined. In paper I, electrophysiological indices of phonological processing under conditions that either allowed for, or limited, involvement of explicit processing were investigated. While the overall purpose was to test if working memory processing of phonology and individual differences in WMC could compensate for phonological decline in individuals with HI, paper II also tested a proposal made by the Ease of Language Understanding (ELU) model . The ELU postulates that individual differences in WMC will modulate task performance under conditions with increased occurrence of phonological mismatch, as in rhyme judgment of written words with mismatching orthography by individuals with degraded phonological representations.Paper IV examined performance on the reading span test (RST;Rönnberg, Lyxell, Arlinger, & Kinnefors, 1989), the measure of WMC used in papers I-III, in a larger sample of individuals with HI who had participated in different projects from our laboratory and its collaborators. The test is theoretically anchored in the capacity theory of working memory (Just & Carpenter, 1992) and plays an important role in the ELU model. Test performance in two different age groups were compared (50-69, 70-89), and the original version of the test was compared to a shortened version. Examination of the relation between test performance and speech recognition in noise was also conducted.The results replicated previous findings of phonological processing declines following acqu...