The interaction of segmental and prosodic structure in speech production: A comparison of syndromes and an investigation of auditory rhythmical priming effects.

• Applicants: Professorin Dr. Simone Falk; Professor Dr. Wolfram Ziegler
• Subject Area: Personality Psychology, Clinical and Medical Psychology, Methodology ; Human Cognitive and Systems Neuroscience
• Term: from 2010 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 173836655

During the first research period of this project we were able to demonstrate a robust effect of rhythm and meter on speech accuracy in word and phrase repetition in apraxic speakers, in the sense that patients made fewer errors on utterances with a regular trochaic rhythm as compared to iambic words or to phrases with irregular stress patterns. These results are in accordance with predictions from an earlier nonlinear model according to which the segmental and the metrical properties of speech motor plans are hierarchically nested. Our results entail two important questions to be answered in an extension of the current project.(1) Is the advantage of regular speech rhythm confined to impairments at the motor planning stage of speech production (i.e., apraxia of speech), or does it also apply to phonological encoding impairments (lexical, post-lexical) or to impairments of speech motor execution (dysarthria). The presence of a uniform metrical influence on speech across several speech output components would be theoretically most revealing. Any disparity between components, on the other hand, might have implications for the differential diagnosis of speech impairments.(2) Do patients with phonological, phonetic, or dysarthric impairment profit, in their speech production, from auditory priming by speech with a regular intrinsic rhythm? This research question interlinks the motor with the sensory domain and hooks up with theories according to which speech motor planning and coordination results from a rhythmical entrainment of articulatory gestures. We are planning for two studies. In study 1, the word repetition paradigm used during the first research period will be expanded by a naming paradigm, in order to systematically investigate the influence of word stress on picture naming in aphasic patients with lexical (post-semantic) impairment. In study 2 we will use a new auditory-motor coupling paradigm which requires participants to complete a phrase spoken by a model speaker by maintaining the rhythm and fluency of the auditory model. This approach is based on an adaptation of speech synchronization and turn taking experiments. It will allow us to distinguish between auditory and motor influences on segmental and rhythmical aspects of spoken language production. We plan to examine speakers with phonological impairment, apraxia of speech, and (Parkinsons) dysarthria, thereby complementing our cross-syndrome comparisons. By using a paradigm related to the synchronization approach we also build a bridge to well established, rhythm based treatment methods from other motor domains.

• DFG Programme: Research Grants