Synergistic modes of vocal tract articulation for American English vowels

Abstract

The purpose of this study was to investigate the spatial similarity of vocal tract shaping patterns across speakers and the similarity of their acoustic effects. Vocal tract area functions for 11 American English vowels were obtained from six speakers, three female and three male, using magnetic resonance imaging (MRI). Each speaker's set of area functions was then decomposed into mean area vectors and representative modes (eigenvectors) using principal components analysis (PCA). Three modes accounted for more than 90% of the variance in the original data sets for each speaker. The general shapes of the first two modes were found to be highly correlated across all six speakers. To demonstrate the acoustic effects of each mode, both in isolation and combined, a mapping between the mode scaling coefficients and [F1, F2] pairs was generated for each speaker. The mappings were unique for all six speakers in terms of the exact shape of the [F1, F2] vowel space, but the general effect of the modes was the same in each case. The results support the idea that the modes provide a common system for perturbing a unique underlying neutral vocal tract shape.

Identification of synthetic vowels based on selected vocal tract area functions

“…Previously published area functions for eight speakers were used to synthesize vowel samples in the present study ͑Story et al, 1996͑Story et al, , 1998Story, 2005a͒. This included four male ͑range 29-40 years͒ and four female ͑range 23-39 years͒ speakers.…”

“…These collections of area functions, which are assumed representative of an individual speaker's production of a target vowel or consonant, have then been used in the development of speech production models and speech synthesizers ͑e.g., Ciocea, 1997;Story, 2005aStory, , 2005bMullen et al, 2007͒. The similarity of speech sounds produced by areafunction-based synthesis to natural speech has been typically assessed by comparing calculated formant frequencies to formant frequencies extracted from recorded speech ͑Story et , 1998Story, 2005a͒. Reasonable similarity has been demonstrated; however, stimuli generated based on measured area functions have rarely been evaluated perceptually.…”

The effects of physiological adjustments on the perceptual and acoustical characteristics of vibrato as a model of vocal tremor

“…Prior to the experiment, each listener participated in a brief training protocol consisting of 16 pairs of simulated vowels that were produced using a kinematic model of the vocal folds (Titze, 1984(Titze, , 2006 coupled to a wave-reflection model of the trachea and vocal tract (Liljencrants, 1985;Story, 2005). These simulated vowels had different extents of modulation (1%, 5%, 10%, 20%), one neutral vowel (/@/), and one f o (either 123 Hz for the male simulations or 247 Hz for the female simulations).…”

A comparison of vocal tract perturbation patterns based on statistical and acoustic considerations

“…Statistical analyses of collections of tongue configurations or complete vocal tract shapes (i.e., area functions) have revealed that a small number of canonical deformation patterns (variously referred to as factors, components, basis functions, or modes) can explain most of the variation in vocal tract shape during vowel production (Harshman et al, 1977;Shirai and Honda, 1977;Jackson, 1988;Johnson et al, 1993;Nix et al, 1996;Story and Titze, 1998;Hoole, 1999;Zheng et al, 2003;Iskarous, 2005;Story, 2005;Mokhtari et al, 2007). These deformation patterns tend to exhibit similarities in shape across speakers and are related to specific formant frequency patterns when superimposed on a mean or neutral vocal tract shape.…”