Efficacy of a Semi-occluded Mask in the Treatment of Patients With Voice Disorders

Overview

Current semi-occluded vocal tract therapies limit the type of vocalizations that can be produced to single vowels, which does not promote learning of the healthy voice behavior in connected speech or generalization to conversation. However, recent preliminary results using a semi-occluded mask indicate that the use of certain mask port diameters may allow for natural speech production while increasing supraglottal pressure and impedance, and thereby result in elicitation of voice with increased efficiency. In addition, the use of a semi-occluded mask provides the possibility for a better transition from phonating single phonemes in therapy to training the target therapy techniques in connected speech.

Treatment of voice disorders varies but often involves voice therapy and/or surgical intervention. Voice therapy, a non-invasive behavioral treatment for voice disorders, helps patients develop beneficial voice habits, prevents recurrence of voice disorders, and facilitates long-lasting vocal improvement. Many voice therapy techniques involve a semi-occluded vocal tract (SOVT). SOVT treatment is often characterized by sustained (straw phonation, voiced fricatives, nasals), oral oscillatory (lip buzzes, tongue trills, raspberries) or transitory phonation (plosives and glides). Straw phonation therapy, one of the most utilized SOVT methods, was first proposed in 1904 and involved phonating at different pitches into small glass tubes with varying diameters and lengths providing simultaneous semi-occlusion and extension of the vocal tract. Voice therapy exercises involving voice production with a semi-occluded and sometimes lengthened vocal tract have demonstrated improved vocal efficiency and loudness, reduced mechanical trauma to the vocal fold mucosa, and improved source-filter interaction.Our group recently developed a semi-occluded facemask for use in patients with and without voice disorders. Recent preliminary results using this semi-occluded facemask indicated that the use of a certain mask port diameters may elicit voice with increased efficiency. A study of 5 participants without voice disorders revealed that a mask occlusion diameter of 6.4 and 3.2 mm resulted in improved vocal efficiency. A study of the immediate effects of a semi-occluded facemask in 20 patients with voice disorders revealed that occlusions diameters of 9.6, 6.4, and 3.2 mm all resulted in significant improvements in acoustic and aerodynamic voice outcomes.