Measuring Vocal Tract Agility from Videofiberscopic Data: The Human BeatBox Example
Résumé
Scales have been developed to report efficiently muscle-mucosal relationship at the vocal fold and false vocal folds level, and their consequences on voicing and vocal timbre. Our study is three fold: i) we created a qualitative three-dimensional anatomical-dynamic visual scale OCM (Open, Close, Movement) to describe the vocal tract;; ii) moreover, we developed Matlab software to quantify the changes in the two axes at the laryngeal and pharyngeal levels;; iii) we illustrated our qualitative and quantitative scales on a special vocal technique called the Human Beatbox. The aim of this study was to quantify laryngo-pharyngeal mobility and adjustments for stylistic effects in this vocal technique.
We have performed a descriptive analysis of three beatboxers by observing their vocal tract behaviour with fiberscopic imaging. The corpus was based on the production of three groups of sounds: the "bass sounds", the "instrumental sounds" and the "electronic sounds".
Results: From an anatomical-dynamic point of view, beatboxers mobilise all the structures of their laryngo-pharynx separately. We could describe four types of laryngo-pharyngeal configuration and three dynamic elements. For example, our first results concerning the "percussion sounds" show that the width of the false vocal folds makes the difference while the glottis is completely closed. There is nearly no movement at the ary-epiglottic level.
The measurement scale is a valuable tool to describe vocal tract agility and can be applied to describe physiological behaviour in different artistic or linguistic situations but can also be used to quantify pathological pharyngo-laryngeal movements and help to understand compensation strategies and guide the rehabilitation process.