Morphology and development of the human vocal tract: A study using magnetic resonance imaging

TLDR

MRI was used to quantify vocal tract morphology in 129 normal humans aged 2–25, with morphometric data collected via computer graphics. The study found that vocal tract length positively correlates with body size, that sex differences in morphology emerge at puberty, and that these results provide a normative standard with implications for speech recognition, forensics, and evolutionary studies.

Abstract

Magnetic resonance imaging was used to quantify the vocal tract morphology of 129 normal humans, aged 2-25 years. Morphometric data, including midsagittal vocal tract length, shape, and proportions, were collected using computer graphic techniques. There was a significant positive correlation between vocal tract length and body size (either height or weight). The data also reveal clear differences in male and female vocal tract morphology, including changes in overall vocal tract length and the relative proportions of the oral and pharyngeal cavity. These sex differences are not evident in children, but arise at puberty, suggesting that they are part of the vocal remodeling process that occurs during puberty in males. These findings have implications for speech recognition, speech forensics, and the evolution of the human speech production system, and provide a normative standard for future studies of human vocal tract morphology and development.