This paper describes the results of a study of the effect of speaking rate on the articulation of the consonants /p,w/, in combination with the vowels /i,a,u/. Two subjects read a list of nonsense syllables containing /p,w/, in all possible VCV combinations with /i,a,u,/ at both moderate and fast speaking rates. EMG recordings from muscles that control movements of the lips, tongue, and jaw were recorded simultaneously with high-speed lateral-view x-ray films of the tongue and jaw, and high-speed full-face motion pictures of the lips. For labial consonant production, an increase in speaking rate is accompanied by an increase in the activity level of the muscle (orbicularis oris) and slightly faster rates of lip movement (both closing and opening). Vowel production, however, shows opposite effects: an increase in speaking rate is accompanied by a decrease in the activity level of the genioglossus muscle and, as shown by the x-ray films, evidence of target undershoot. Jaw movement data show more variable, context-dependent effects of speaking rate. Observed differences are explained in terms of the muscle systems involved.

Laryngeal muscle activity during fluent and stuttered utterances was investigated via electromyography. Analysis revealed that stuttering was accompanied by high levels of laryngeal muscle activity and disruption of normal reciprocity between abductor and adductor muscle groups. Results are interpreted as demonstrating the existence of a laryngeal component in stuttering and showing a strong correlation between abnormal laryngeal muscle activity and moments of stuttering.

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The aim of the present study was to investigate the laryngeal adjustments for voiced versus voiceless distinction in Japanese consonant production by means of laryngeal electromyography (EMG) and fiberoptic observation. Multichannel EMG recordings were taken of a Japanese subject and the data were computer-processed to obtain the averaged activity patterns of the five intrinsic laryngeal muscles with special reference to the voicing distinction in consonant production in various phonetic environments. It was found that there were apparent reciprocal patterns in the posterior cricoarytenoid (PCA) and the interarytenoid (INT) in terms of significant negative correlation, and active control of PCA for voicelessness was demonstrated. The patterns of the thyroarytenoid and the lateral cricoarytenoid were different from that of INT even though these two muscles are usually classified as the members of the adductor group, and their activity levels were apparently influenced by the phonetic environment. A possible contribution of the cricothyroid (CT) to the voicing distinction was also pointed out but further investigations on acoustic parameters seem to be mandatory in more critical interpretation of CT activity in speech.