The present study sought to characterize 3D tongue shape for the phones [s], [/], [I] and [a], and to detail C to V movement. The study examined multiple cross-sectional tongue profiles extracted from ultrasound images. The profiles were fit with second order functions and sufficiently characterized in 2D by the a0 and a2 terms, ie, midsagittal tongue height and concavity/convexity. Results provided "shape signatures" for the individual phones that were biologically transparent and reduced tongue shape complexity.