Quantitative characterization of vowel formant transitions

Abstract

This paper presents an acoustic study of vowel formant dynamics and the analysis methods that were developed to carry it out. The main goal of the described study was to bring quantitative, acoustic evidence to bear on competing theories regarding the source(s) of vowel identity specification [W. Strange, J. Acoust. Soc. Am. 85, 2081–2087 (1989)]. A set of 40 CVC syllables are studied: symmetric voiced stop (/bVb/, /dVd/, /gVg/) and ‘‘neutral’’ (/hVd/) contexts × the ‘‘monopthongal’’ vowels of Midwestern American English (/i,i,e,eh,æ,Λ,u,u,o,a/). Three male speakers (speaking normally) contributed two repetitions each. Voice pulse by voice pulse tracks of the first three formant frequencies were measured using GEMS [J. Talley, J. Acoust. Soc. Am. 90, 2274 (A) (1991)] and LPC. PEACC, a new technique for speech coding using exponential pieces, was then applied to the trajectories to automatically segment them into transitions and characterize the segments in terms of intuitive parameters−Δf (‘‘locus-to-target’’ distance), Δt (duration), α (curvature), and f0 (‘‘target’’ frequency). This paper discusses the resulting data’s characteristics and the results from analyzing initial and final transitions with respect to intracategory similarity and intercategory distinctiveness using a variety of interesting category boundaries. [Work supported by NSF.]