Dynamic Characteristics of Vocal Frequency Tracking in Stutterers and Nonstutterers
The production of speech requires delicate coordination between laryngeal, articulatory and respiratory systems. Neurophysiology suggests that this coordination is achieved through the use of negative feedback control systems. That is, the central nervous system monitors proprioceptive feedback from these systems while it also monitors speech output through the auditory system. Actual speech output is compared to desired output, and corrective adjustments are made. Systems that use feedback (closed looped systems), like the CNS, are capable of much finer control than those that do not (open loop systems) because of their ability to monitor performance and make adjustments in their output. The price paid for this increase in performance is the possibility of the system becoming unstable, i.e., the adjustments that are made tend to degrade the performance rather than improve it. It is proposed to model stuttering as such an instability in the speech motor system. By studying the causes of these instabilities, we can understand the conditions leading to the production of a stuttered disfluency.
KeywordsModulation Frequency Sine Wave Speech Motor Fluent Speaker Auditory Delay
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