Posterior cricoarytenoid as a speech muscle.

It is well known that the posterior crioarytenoid muscle (PCA) is the only abductor of the vocal folds, but its role in speech has not fully been clarified. Our recent electromyographic (EMG) studies indicate active participation of PCA in the production of voiceless consonants and breathy phonation in different languages. In the experiments to be reported here, computer-averaged EMG data were obtained from PCA of native speakers of American English, Japanese, and Danish who uttered test words embedded in frame sentences. The results indicated that there was consistent increases in PCA activity for the voiceless portion of the test words. The EMG results were compared to the degree of glottal opening estimated by means of the fiberoptic technique. It was suggested that the degree and timing of PCA activity were directly responsible for determining the size and temporal course of the glottal opening for voiceless segments, although the suppression of the adductors might also have to be taken into consideration for a complete description of voiceless segment production.