Coordination of tongue muscle shortening and volume shifting in speech

Abstract

Tongue motion to execute speech motions uses complex 3-D muscle architecture. For example, the motion into /s/ requires the tongue to extend its tip anteriorly, groove its superior surface, and brace itself laterally. To facilitate this, orthogonal, interdigitated tongue muscles allow complex deformations and motions, which create subtle and local shape changes along the tongue surface. This talk will examine anterior-posterior tongue motion from two perspectives: muscle shortening and volume shifting. We measure tagged and cine MR images for two speech tasks, “a geese” versus “a souk,” which move the tongue primarily forward versus backward. The talk will focus on the genioglossus, verticalis, transverse, superior, and inferior longitudinal muscles. These five muscles comprise over 50% of the tongue mass and deform it in three major directions: anterior-posterior, superior-inferior, and medial-lateral. The muscle shortening patterns will be compared to the percent of the tongue anterior to specific tooth landmarks for the consonant /s/ in both words. The /s/’s differ in word position and vowel context. Similarities between the two will help specify the coordination between muscles and deformation for /s/; differences will inform us as to the effect of vowel context/word placement.