Vocal exercise may attenuate acute vocal fold inflammation

Comparison of Vocal Vibration-Dose Measures for Potential-Damage Risk Criteria

PURPOSE

Schoolteachers have become a benchmark population for the study of occupational voice use. A decade of vibration-dose studies on the teacher population allows a comparison to be made between specific dose measures for eventual assessment of damage risk.

METHOD

Vibration dosimetry is reformulated with the inclusion of collision stress. Two methods of estimating amplitude of vocal-fold vibration are compared to capture variations in vocal intensity. Energy loss from collision is added to the energy-dissipation dose. An equal-energy-dissipation criterion is defined and used on the teacher corpus as a potential-damage risk criterion.

RESULTS

Comparison of time-, cycle-, distance-, and energy-dose calculations for 57 teachers reveals a progression in information content in the ability to capture variations in duration, speaking pitch, and vocal intensity. The energy-dissipation dose carries the greatest promise in capturing excessive tissue stress and collision but also the greatest liability, due to uncertainty in parameters. Cycle dose is least correlated with the other doses.

CONCLUSION

As a first guide to damage risk in excessive voice use, the equal-energy-dissipation dose criterion can be used to structure trade-off relations between loudness, adduction, and duration of speech.

A taxonomy of voice therapy

PURPOSE

Voice therapy practice and research, as in most types of rehabilitation, is currently limited by the lack of a taxonomy describing what occurs during a therapy session (with enough precision) to determine which techniques/components contribute most to treatment outcomes. To address this limitation, a classification system of voice therapy is proposed that integrates descriptions of therapeutic approaches from the clinical literature into a framework that includes relevant theoretical constructs.

METHOD

Literature searches identified existing rehabilitation taxonomies/therapy classification schemes to frame an initial taxonomic structure. An additional literature search and review of clinical documentation provided a comprehensive list of therapy tasks. The taxonomy's structure underwent several iterations to maximize accuracy, intuitive function, and theoretical underpinnings while minimizing redundancy. The taxonomy was then used to classify established voice therapy programs.

RESULTS

The taxonomy divided voice therapy into direct and indirect interventions delivered using extrinsic and/or intrinsic methods, and Venn diagrams depicted their overlapping nature. A dictionary was developed of the taxonomy's terms, and 7 established voice therapy programs were successfully classified.

CONCLUSION

The proposed taxonomy represents an important initial step toward a standardized voice therapy classification system expected to facilitate outcomes research and communication among clinical stakeholders.

Using Semi-Occluded Vocal Tract Exercises in Voice Therapy: The Clinician's Primer

Semi-occluded vocal tract (SOVT) exercises have long been used by voice trainers and pedagogues and have been particularly popular in Scandinavia dating as far back as the 1800s. Titze (1988, 1994, 2006; Titze, Riede, & Popolo, 2008; Titze & Verdolini-Abbot, 2012) has contributed significantly to the exploration of the SOVT and impact on voice production, and these types of exercise have become ubiquitous in the clinical voice arena. Although SOVT exercises are commonly used, there continue to be questions about the exact nature of how they impact phonation and improved vocal economy. This article aims to explore the physiology of a SOVT on vocal fold vibration and vocal output. Several variations are described within context of recent research.

Perioperative Voice Recovery: An Exercise Physiology Perspective

Voice professionals have differing views on the amount of voice rest prescribed before and after laryngeal surgery. Current recommendations are largely based on a long-standing belief that voice rest is good for the vocal mechanism, particularly when pathology is present or following surgical interruption of the vocal fold tissue. There is little evidence to support the benefit of extensive voice rest prior to laryngeal surgery, as is often recommended in the performing arts. In fact, preoperative voice therapy has shown benefit for postoperative voice outcome. From a wound-healing perspective, voice conservation immediately following vocal fold surgery contributes to the best vocal function outcome. There is no supportive evidence for postoperative voice rest that extends for weeks into months, as some performing artists have reported following surgery. From the perspective of skeletal muscle cell physiology and what is currently known about skeletal muscle adaptations that occur with training and detraining, a guideline for optimal voice recovery and return to performance may be clearer. The well-intentioned, long-held belief that extensive voice conservation is good for the voice may actually trigger a skeletal muscle detraining cascade that could lengthen return to optimal voice function, particularly in the vocal performing arts.

Current Understanding and Future Directions for Vocal Fold Mechanobiology

The vocal folds, which are located in the larynx, are the main organ of voice production for human communication. The vocal folds are under continuous biomechanical stress similar to other mechanically active organs, such as the heart, lungs, tendons and muscles. During speech and singing, the vocal folds oscillate at frequencies ranging from 20 Hz to 3 kHz with amplitudes of a few millimeters. The biomechanical stress associated with accumulated phonation is believed to alter vocal fold cell activity and tissue structure in many ways. Excessive phonatory stress can damage tissue structure and induce a cell-mediated inflammatory response, resulting in a pathological vocal fold lesion. On the other hand, phonatory stress is one major factor in the maturation of the vocal folds into a specialized tri-layer structure. One specific form of vocal fold oscillation, which involves low impact and large amplitude excursion, is prescribed therapeutically for patients with mild vocal fold injuries. Although biomechanical forces affect vocal fold physiology and pathology, there is little understanding of how mechanical forces regulate these processes at the cellular and molecular level. Research into vocal fold mechanobiology has burgeoned over the past several years. Vocal fold bioreactors are being developed in several laboratories to provide a biomimic environment that allows the systematic manipulation of physical and biological factors on the cells of interest in vitro. Computer models have been used to simulate the integrated response of cells and proteins as a function of phonation stress. The purpose of this paper is to review current research on the mechanobiology of the vocal folds as it relates to growth, pathogenesis and treatment as well as to propose specific research directions that will advance our understanding of this subject.