Spectral analyses of activity of laryngeal and orofacial muscles in stutterers.

Previous studies have reported that the disfluent speech of stutterers is often associated with tremor in orofacial muscle systems. In the present report, spectral analyses of the amplitude envelopes of laryngeal and orofacial EMGs revealed that tremor-like oscillations of EMG activity, similar to those observed in orofacial muscles, are also present in laryngeal muscles during stuttered speech. Furthermore, tremor-like oscillations in orofacial and laryngeal muscles appear to be entrained in some subjects. It is speculated that autonomic systems may provide a mechanism whereby oscillations in different muscle groups may become entrained.