Producing syllables: motor planning, motor programming and execution

Authors: Bernd J. Kröger, Trevor Bekolay

Abstract:

Speech production is a hierarchically organized process involving cortical, subcortical, and peripheral components. While the cognitive-linguistic processing levels are already investigated extensively this is not the case for the sensorimotor levels. We here introduce a neurobiologically inspired quantitative and computer-implemented production model in which four main modules can be separated: (i) linguistic planning (from concepts via lemmas towards phonological forms including syllabification), (ii) motor planning (establishing a raw gesture score), (iii) motor programming (establishing a fully specified gesture score including specification of muscle activation patterns for execution), and (iv) execution (i.e., generation of articulatory movements and of the acoustic speech signal). This quantitative computer-implemented production model is capable of producing all syllables of Standard German. The model allows a detailed description of motor planning, motor programming, and execution and it includes a detailed and quantitative concept for generating syllables by using speech movement units (also called gestures) as basic production units. This paper concentrates on detailed structuring of gestures, i.e., by calculating the contribution of different articulators in the realization of target-directed speech movement units realizing linguistically relevant vocal tract constrictions.