Mechanism of Glottal Vibration for Vowels and Consonants

It is suggested that the positioning of the vocal cords and the manner in which they vibrate may be quite different, depending upon whether the supraglottal tract is unconstricted, as in vowels, or whether it is constricted to some degree, as in stops, fricatives, and certain semivowels. An analysis of the mechanism of larynx vibration and measurements of air‐flow events during speech shows that vocal‐cord vibration of the type that occurs in vowels cannot be maintained during voiced consonants, and that adjustments in vocal‐cord positioning and tension must be made if vibration is to continue. Since these adjustments require a certain time interval to be effected, they account—at least in part—for the frequently noted differences in vowel length before voiceless consonants, nasals, and voiced obstruents. [This work was supported in part by the U. S. Air Force, under contract, and in part by the National Institutes of Health, U. S. Department of Health, Education, and Welfare, under a grant.]