Approche expérimentale de la collision entre les plis vocaux en phonation et du phonotraumatisme : Études in vivo et sur larynx humains excisés

The collision between the vocal folds during phonation is a physiological phenomenon
with a powerful role in the synchronization of their vibration. This collision is also a
component of the phonotrauma.
The role of phonotrauma in the pathophysiology of dysphonia is commonly accepted
but its nature still unclear and its quantification remains difficult. This work proposes, an in
vivo study in healthy subjects, and ex vivo ones on excised human larynges.
The purpose of this work was to study the laryngeal behavior when the larynx is
subjected to extremely high subglottic pressure. In vivo, the shouted voice was recorded with
constant measure of subglottic pressure. Ex vivo, the subglottic pressure was directly
manipulated independently from other parameters. The ex vivo study required a
methodological development to modernize the experimental bench used for animal larynges
studies and to adapt it to the human larynx.
The results showed, in healthy speakers the existence of a "plateau" in the vocal
intensity and in the electroglottographic signal for very high levels of subglottic pressure. The
studies on excised larynges measured the collision force between the vocal folds and its
changes depending on subglottic pressure. They also highlighted the existence of a "plateau"
in the collision force when subglottic pressure was very high.
The observations presented in this work are, to our knowledge, unprecedented. They
have important clinical interest for understanding the concept of phonotrauma. Their
interpretation in physical terms remains very incomplete.