Hemi-laryngeal Setup for Studying Vocal Fold Vibration in Three Dimensions

Christian T. Herbst; Vit Hampala; Maxime Garcia; Riccardo Hofer; Jan G. Svec

doi:10.3791/55303

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Method Article

Hemi-laryngeal Setup for Studying Vocal Fold Vibration in Three Dimensions

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DOI:

10.3791/55303

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November 25th, 2017

Christian T. Herbst¹^,² , Vit Hampala¹ , Maxime Garcia²^,³ , Riccardo Hofer² , Jan G. Svec¹

¹Voice Research Lab, Department of Biophysics, Faculty of Science, Palacky University Olomouc, ²Laboratory of Bio-Acoustics, Dept. of Cognitive Biology, University of Vienna, ³ENES Lab, NEURO-PSI,CNRS UMR 9197, Université Lyon/Saint-Etienne, France

Summary

This paper introduces a protocol for the preparation of hemi-larynx specimens facilitating a multi-dimensional view of vocal fold vibration, in order to investigate various biophysical aspects of voice production in humans and non-human mammals.

Abstract

The voice of humans and most non-human mammals is generated in the larynx through self-sustaining oscillation of the vocal folds. Direct visual documentation of vocal fold vibration is challenging, particularly in non-human mammals. As an alternative, excised larynx experiments provide the opportunity to investigate vocal fold vibration under controlled physiological and physical conditions. However, the use of a full larynx merely provides a top view of the vocal folds, excluding crucial portions of the oscillating structures from observation during their interaction with aerodynamic forces. This limitation can be overcome by utilizing a hemi-larynx setup where one half of the larynx is mid-sagittally removed, providing both a superior and a lateral view of the remaining vocal fold during self-sustained oscillation.

Here, a step-by-step guide for the anatomical preparation of hemi-laryngeal structures and their mounting on the laboratory bench is given. Exemplary phonation of the hemi-larynx preparation is documented with high-speed video data captured by two synchronized cameras (superior and lateral views), showing three-dimensional vocal fold motion and corresponding time-varying contact area. The documentation of the hemi-larynx setup in this publication will facilitate application and reliable repeatability in experimental research, providing voice scientists with the potential to better understand the biomechanics of voice production.

Introduction

Voice is typically created by vibrating laryngeal tissue (mainly the vocal folds), which converts a steady airflow, supplied by the lungs, into a sequence of airflow pulses. The acoustic pressure waveform (i.e., the primary sound) emerging from this sequence of flow pulses acoustically excites the vocal tract which filters them, and the resulting sound is radiated from the mouth and (to a certain degree) from the nose¹. The spectral composition of the generated sound is largely influenced by the quality of vocal fold vibration, governed by laryngeal biomechanics and interactions with the tracheal airflow². Both ....