“…They are configured such that one pattern produces a continuum from /i/-like to /a/-like vocal tract shapes while another represents an /æ/-like to /u/-like continuum, suggesting that they represent a coordination of the speech articulators necessary for vowel production. The results are similar to factor analyses of tongue shape (Harshman, Ladefoged, and Goldstein, 1977; Shirai and Honda, 1977; Nix, Papcun, Hogden, and Zlokarnik, 1996; Zheng, Hasegawa-Johnson, and Pizza, 2003), shaping components used in other articulatory models (Berry, 2003; Maeda, 1990, 1991), as well as analogous research on vocal tract area functions (Mokhtari et al, 2007). Some recent work has also shown that the shape of these patterns can be derived theoretically from calculations of acoustic sensitivity functions of the nonuniform neutral area functions of speakers (Story, 2007).…”