ABSTRACT
Speaking is perhaps the most complex fine motor skill that humans can perform. The production of fluent speech requires the translation of abstract linguistic units into constantly changing movement sequences of the motor speech subsystems subserving articulation, phonation and respiration. Although a unitary definition of stuttering currently evades researchers, its primary expression lies in some incoordination within and between these three major motor speech subsystems. We see this with articulatory struggle, visible and auditory difficulties in commencing or terminating phonation and in spasmodic and poorly-timed breathing for speech. In other words, stuttering presents as a motor speech disorder. But to acknowledge that it presents as a motor control problem is not the same as concluding that stuttering is, in essence, a motor speech disorder. The speech of all but those with the most severe stuttering is of an output that is only intermittently interrupted by aberrant motoric activity. In fact, as we will come to see, findings show that while we may perceive nonstuttering speech as fluent, there is nonetheless evidence for consistent abnormal motor speech activity, even in the absence of observable stuttering.
