A STUDY OF ARTICULATORY MOTOR FUNCTION AND ITS VARIABILITY AT THE NEURO-MUSCULAR LEVEL

Abstract

Observations on the intra-subject variability of articulatory motor function and its bioinformative analysis were performed in order to clarify the sensory motor feedback self-controlled function in hearing and speech behavior at the neuro-muscular level.
Mean action potential amplitude (MAPA) calculated through the computer from each EMG recording of the orbicularis oris were displayed together with raw EMG and speech signals by an X-Y recorder. Measurements of the timing of the articulatory motor function were conducted on the intervals from the onset of EMG activity to its peak, to its end, and to voicing, and from the end of EMG to voicing. Mean values of each measurement were almost the same as that shown in previous papers which studied on a monosyllable including bilabial explosive consonant (/Pa/).
Inter-subject standard deviations of each measurement were large, indicating wide individual variation in speech behavior. However, intra-subject standard deviations were small and variation in the measurement of 60 times showed normal distribution, which seemed to well indicate a self controlled function, except for the interval from the onset of EMG to voicing.
The author claimed that the self controlled physiological function in hearing and speech behavior was verified at the neuro-muscular level, and further suggested that the measurement of intra-subject variability in speech behavior would give us useful information on the pathology, diagnosis and prognosis of speech disorders.