Facilitating and disrupting speech perception in word deafness

Abstract

Background: Word deafness is a rare condition where pathologically degraded speech perception results in impaired repetition and comprehension but otherwise intact linguistic skills. Although impaired linguistic systems in aphasias resulting from damage to the neural language system (here termed central impairments), have been consistently shown to be amenable to external influences such as linguistic or contextual information (e.g. cueing effects in naming), it is not known whether similar influences can be shown for aphasia arising from damage to a perceptual system (here termed peripheral impairments). Aims: This study aimed to investigate the extent to which pathologically degraded speech perception could be facilitated or disrupted by providing visual as well as auditory information. Methods and Procedures: In three word repetition tasks, the participant with word deafness (AB) repeated words under different conditions: words were repeated in the context of a pictorial or written target, a distractor (semantic, unrelated, rhyme or phonological neighbour) or a blank page (nothing). Accuracy and error types were analysed. Results: AB was impaired at repetition in the blank condition, confirming her degraded speech perception. Repetition was significantly facilitated when accompanied by a picture or written example of the word and significantly impaired by the presence of a written rhyme. Errors in the blank condition were primarily formal whereas errors in the rhyme condition were primarily miscues (saying the distractor word rather than the target). Conclusions: Cross-modal input can both facilitate and further disrupt repetition in word deafness. The cognitive mechanisms behind these findings are discussed. Both 4 top-down influence from the lexical layer on perceptual processes as well as intralexical competition within the lexical layer may play a role.

Therapy for auditory processing impairment in aphasia: An evaluation of two approaches

“…Woolf concluded that these participants were using meaning to compensate for their impaired speech perception. Rather similar findings are reported by Robson and colleagues (Robson, Davies, Lambon-Ralph & Sage, 2012).…”

Neurocognitive insights on conceptual knowledge and its breakdown

“…posterior superior temporal gyrus) but multimodal impairments when the lesions are larger and encroach on the transmodal areas (e.g. posterior middle temporal and inferior parietal regions: [30,31]).…”

“…R. Soc. B 369: 20120392 comparative studies of chronic Wernicke's aphasia [31,33] which, in addition to a strong modality difference (spoken words , written words , picture comprehension), have found that the patients' multi-modal semantic impairment has the features of semantic aphasia (control deficits) rather than SD (i.e. representational degradation).…”

Auditory agnosia

“…Speech production in verbal auditory agnosia is relatively normal (Table 32.1), although in some cases production is overly loud and has abnormal prosody (e.g., Otsuki et al, 1998;J€ orgens et al, 2008). Speech perception is typically improved by relying on cross-modal information such as lip reading and from "top-down" contextual information (e.g., Saffran et al, 1976;Coslett et al, 1984;Buchtel and Stewart, 1989;Slevc et al, 2011;Robson et al, 2012). Perception is also sometimes improved by dramatically slowing the speech signal (Albert and Bear, 1974;Stefanatos et al, 2005a), perhaps by ameliorating some patients' particular difficulty with rapid temporal aspects of the speech signal (see below).…”