Three kinds of data were used in an attempt to determine the parameters of characteristic lip positions in a range of American English vowels: (1) standardized simultaneous frontal and lateral photographs; (2) lateral x-rays; (3) plaster casts of a subject's lips. Among the measurements taken were the following: (1) distance between the corners of the mouth (width); (2) height of the opening on the midline; (3) area as measured on a frontal view; (4) protrusion; (5) retraction of the corners of the mouth. As a check on the consistency of measurement and performance, these data were used to compare a single subject's production of the set of vowels on a number of occasions. Comparisons with other subjects were also made. The interrelationships of these variables are discussed.
