Compensation Strategies in Voice Production With Glottal Insufficiency.

OBJECTIVES: This study evaluates potential compensation strategies under conditions of glottal insufficiency.
METHODS: Using a numerical respiratory-laryngeal model of voice production, voice production under conditions of glottal insufficiency is investigated across a large range of voice conditions, and compared with normal voice production.
RESULTS: This study shows that glottal insufficiency leads to increased noise production, reduced fundamental frequency range, and inability to produce very low-intensity voice. Glottal insufficiency also leads to significantly increased respiratory effort of phonation and difficulty in maintaining a normal breath group duration, which restricts high-intensity voice production and falsetto-like voice production. Although compensation strategies exist to alleviate these undesirable voice changes, they often require hyperfunctional laryngeal and respiratory muscle activities and thus are more likely to result in vocal fatigue.
CONCLUSIONS: The laryngeal and respiratory subsystems need to be considered as a whole to fully understand the effect of glottal insufficiency on voice production. Strategies that compensate for laryngeal weakness at the cost of compromising the normal function of the respiratory subsystem are undesirable and may impose additional constraints on voice production and the effectiveness of available compensation strategies.