Involuntary Inspiratory Phonation
Involuntary inspiratory phonation is a vocal phenomenon in which an involuntary vocal sound is made when one breathes in. In other words, a vocal noise such as one might hear from a person who is startled, takes an inward breath, and “gasps.” Inspiratory phonation becomes involuntary (necessary or impossible to abolish) when two conditions are met:
1) The vocal cords are unable to abduct (separate) normally during inspiration.
2) The speed of inspiratory airflow is sufficient to in-draw the cords and set them vibrating.
Conditions that may be associated with this include glottic stenosis, bilateral vocal cord paralysis, chemical denervation of both posterior cricoarytenoid muscles after Botox injection for abductory spasmodic dysphonia. In some cases, involuntary inspiratory phonation is heard only during the elicitations of the vocal capability battery, when the patient is asked to empty the lungs (breathe out fully) and then to fill them completely as rapidly and quietly as possible.