Many voice disorders, such as unilateral vocal fold paralysis, bowing, or lesions, involve an increase in effort, suggesting that voice efficiency is adversely impacted. At present, clinical measures of voice efficiency are seldom used, in part because they are difficult to interpret. This is due, in part, to incomplete understanding of how the energy in the subglottal airstream is partitioned into work sustaining vocal fold vibration, an into producing sound, and how this partition is altered by the disorders previously mentioned. In addition, only acoustic efficiency measures have been proposed. Finally, any clinically realizable measures of voice function necessarily involve approximation, due to the limited access to the larynx. The proposed research takes a three-fold approach to improving our fundamental understanding of voice energy utilization and translating these findings to clinically useful measures. First, using a combination of aeroelastic-aeroacoustic theory, computer simulation, and physical model experiments, energy utilization in the voice will be investigated. These investigations will be performed for three cases: normal phonation (symmetrical vocal folds), unilateral vocal fold paralysis (vocal fold stiffness asymmetry), and vocal fold bowing. Second current and novel measures of energy utilization and efficiency will be benchmarked against the physical model and simulation data. Energy measures will include power transfer to the vocal folds, and to the sound field in the vocal tract, as well as both acoustic and vibration efficiency Using the same data, energy utilization and efficiency measures are estimated in two ways: (1) as completely as possible, using the full extent of the available data, and (2) using limited data, as constrained by the limitations of clinically realizable measurement, using appropriate approximations. Finally, the current and current and novel clinical measures will be estimated using data from patients suffering from disorders that reduce efficiency through biomechanical issues. The proposed research promises to significantly improve our understanding of vocal energy utilization for normal and disordered phonation, and to begin translation of this knowledge to clinically realizable metrics of voice function.
This research will address the underlying physics of phonation, focusing on how the energy in the subglottal airstream is partitioned into work to vibrate the vocal folds and produce sound. Research will also benchmark current and novel clinically realizable measures of phonatory energy utilization, and of voice efficiency.
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