Effects of Repeated Exposure to Synthetic and Digitized Natural Speech by Individuals With Aphasia

Abstract

Purpose Technological supports provide multimodal presentation of text, which may increase understandability of written materials by people with aphasia (PWA). Extant literature reveals that digitized natural speech and synthetic computer-generated speech within these supports are comprehensible by PWA at discrete time points; however, understandability following repeated exposure is unexplored. This pilot study evaluated understanding of, and preference regarding, synthetic and digitized natural speech during and following repeated exposures by PWA. Method This multiple–case-study project included four adults with aphasia. Participants independently completed various listening tasks in a single digitized natural speech condition and one of two synthetic speech conditions across a 2-week period. Participants completed sessions to evaluate maintenance effects and generalization to novel stimuli and an untrained synthetic voice condition 1 week and 1 month following daily practice. Results Study participants demonstrated understandability evident by at- or near-ceiling performance during baseline, practice, and follow-up sessions in the digitized natural condition and one synthetic speech condition. Individuals with mild aphasia achieved relatively consistent performance during independent practice, whereas performance of individuals with moderate aphasia fluctuated in both conditions. All four participants demonstrated variable understanding during generalization and maintenance tasks at follow-up time points. Participants most frequently indicated preference for digitized natural speech over either synthetic speech condition. Conclusions Findings hold important clinical implications when considering feasibility of utilizing these speech forms as compensatory strategies for PWA. Further research is needed to more fully understand the effects of repeated exposure to synthetic speech on comprehension among PWA.