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Objectives/Hypothesis Traditional semi-occluded vocal tract (SOVT) therapies have the benefit of improving vocal economy but, do not allow for connected speech during rehabilitation. In this study, we introduce a semi-occluded face mask (SOFM) as an improvement upon current methods. This novel technique allows for normal speech production, and will make the transition to everyday speech more natural. We hypothesize that use of a SOFM will lead to the same gains in vocal economy seen in traditional methods. Study Design Repeated measures excised canine larynx bench experiment with each larynx subject to controls and a randomized series of experimental conditions. Methods Aerodynamic data were collected for 30 excised canine larynges. The larynges were subjected to conditions including a control, two tube extensions (15 and 30 cm), and two tube diameters (6.5 and 17 mm) both with and without the SOFM. Results were compared between groups and between conditions within each group. Results No significant differences were found between the phonation threshold pressure (PTP) and phonation threshold flow (PTF) measurements obtained with or without the SOFM throughout all extension and constriction levels. Significant differences in PTP and PTF were observed when varying the tube diameter while the same comparison for varying the tube length at least trended towards significance. Conclusions This study suggests that a SOFM can be used to elicit the same gains in vocal economy as what has been seen with traditional SOVT methods. Future studies should test this novel technique in human subjects to validate its use in a clinical setting.

The quantitative results in this study not only provide a numerical reference for future experimental measurements, but also can be used to verify the biphasic model in future studies.

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The main objective of the study is to model asymmetry within anterior glottic webs in excised larynges using sutures and apply aerodynamic and acoustic analyses. Anterior glottic webs (AGW) were modeled in eight excised larynges using sutures secured at the level of the glottis to mimic the scar tissue of the web. Each of the eight larynges were tested under three different pressure increments for each of the three models of AGW: symmetric, vertically asymmetric, and laterally asymmetric. Phonation threshold pressure (PTP) and flow (PTF) differed significantly across AGW conditions (p = 0.006 and p = 0.005, respectively). Additionally, vocal efficiency was significantly different among conditions (p = 0.005) as well as significantly lower in the asymmetric groups (p = 0.015 and p = 0.007). Perturbation measures were not significantly different across conditions. Correlation dimension (D2) was significantly different at PTP, 1.25 × PTP, and 1.5 × PTP (p = 0.003, p = 0.010, and p < 0.001, respectively) as well as significantly higher in the asymmetric groups at each pressure increment. The increased PTP, PTF, and D2 values as well as decreased vocal efficiency among the asymmetric conditions indicates a significant decrease in vocal function, and thus represents that asymmetries could be a contributing factor to the pathological symptoms associated with glottic webs.