Investigating Speech Production in Aphasia: A Usage-Based Approach

Abstract

This research examined how lexical frequency and the strength of multiword sequences influence speech production in individuals with aphasia (IWA) compared with non-aphasic stroke survivors who had recovered their language abilities. Using the AphasiaBank corpus, we analyzed speech from 34 participants with Broca's aphasia, Conduction aphasia, and recovered non-aphasic stroke controls. Speech samples were analyzed in Praat to measure word duration, silent pauses, lexical frequency, and collocation strength, testing predictions derived from a usage-based framework. Partially consistent with our hypotheses, individuals with Broca's aphasia produced higher-frequency words and tended to produce stronger collocations, suggesting greater reliance on entrenched linguistic units. Across all groups, stronger collocations were associated with shorter silent pauses and shorter word durations, indicating that frequency-based facilitation supports speech fluency even after neurological damage. However, group differences in predictability effects were smaller than expected, and facilitation was not consistently strongest in Broca's aphasia, suggesting that usage-based mechanisms alone cannot fully explain speech production in aphasia. These findings support a network-oriented view of language in which fluency emerges from the interaction of experience-dependent linguistic knowledge, cognitive-linguistic processing, and post-stroke neural reorganization. Overall, the study provides evidence that usage-based mechanisms contribute to speech production while highlighting the importance of integrating psycholinguistic and neurolinguistic perspectives to explain variability in aphasic speech.