Kimberly V. Fisher

Oral breathing increases Pth and vocal effort by superficial drying of vocal fold mucosa.

Oral breathing superficially dehydrates the airway lumen by decreasing the depth of the sol layer in humans and animals. Conversely, nasal breathing can increase the humidity of inspired air. We compared the effects of short-term oral and nasal breathing on Pth and perceived vocal effort in 20 female subjects randomly assigned to two groups: oral breathing (N = 10, age 21-32 years); nasal breathing (N = 10, age 20-36 years). We hypothesized that short-term oral breathing, but not nasal breathing, would increase Pth, and that subjects would perceive this change as an increase in vocal effort. Following 15 minutes of oral breathing, Pth increased at comfortable and low pitch (p < 0.01) with 6 of 10 subjects reporting increased vocal effort. Nasal breathing reduced Pth at all three pitches (p < 0.01), and 7 of 10 subjects reported decreased vocal effort. Over all subjects, 49% of the variance in treatment-induced change in Pth was accounted for by change in vocal effort (R = 0.70). We posit that obligatory oral breathing places healthy subjects at risk for symptoms of increased vocal effort. The facilitatory role of superficial hydration on vocal fold oscillation should be considered in biomechanical models of phonation and in the clinical prevention of laryngeal dryness.

Vocal fold surface hydration: a review.

Vocal fold surface liquid homeostasis contributes to optimal vocal physiology. In this paper we review emerging evidence that vocal fold surface liquid is maintained in part by salt and water fluxes across the epithelium. Based on recent immunolocalization and electrophysiological findings, we describe a transcellular pathway as one mechanism for regulating superficial vocal fold hydration. We propose that the pathway includes the sodium-potassium pump, sodium-potassium-chloride cotransporter, epithelial sodium channels, cystic fibrosis transmembrane regulator chloride channels, and aquaporin water channels. By integrating knowledge of the regulating mechanisms underlying ion and fluid transport with observations from hydration challenges and treatments using in vitro and in vivo studies, we provide a theoretical basis for understanding how environmental and behavioral challenges and clinical interventions may modify vocal fold surface liquid composition. We present converging evidence that clinical protocols directed at facilitating vocal fold epithelial ion and fluid transport may benefit healthy speakers, those with voice disorders, and those at risk for voice disorders.

Vocal Warm-up Increases Phonation Threshold Pressure in Soprano Singers at High Pitch

Vocal warm-up is thought to optimize singing performance. We compared effects of short-term, submaximal, vocal warm-up exercise with those of vocal rest on the soprano voice (n = 10, ages 19-21 years). Dependent variables were the minimum subglottic air pressure required for vocal fold oscillation to occur (phonation threshold pressure, Pth), and the maximum and minimum phonation fundamental frequency. Warm-up increased Pth for high pitch phonation (p = 0.033), but not for comfortable (p = 0.297) or low (p = 0.087) pitch phonation. No significant difference in the maximum phonation frequency (p = 0.193) or minimum frequency (p = 0.222) was observed. An elevated Pth at controlled high pitch, but an unchanging maximum and minimum frequency production suggests that short-term vocal exercise may increase the viscosity of the vocal fold and thus serve to stabilize the high voice.

Stroboscopic and acoustic measures of inspiratory phonation

Inspiratory phonation (IP) is the production of voice as air is taken into the lungs. Although IP is promoted as a laryngeal assessment and voice treatment technique, it has been described quantitatively in very few speakers. This study quantified changes in laryngeal adduction, fundamental frequency, and intensity during IP relative to expiratory phonation (EP). We hypothesized that IP would increase laryngeal abduction and fundamental frequency. The experiment was a within-subjects, repeated measures design with each subject serving as her own control. Participants were 10 females (ages 19-50 years) who underwent simultaneous transoral videostrobolaryngoscopy and acoustic voice recording. We found that membranous vocal fold contact decreased significantly during IP relative to EP, while the trends for change of ventricular fold squeeze during IP varied across individuals. Vocal fundamental frequency increased significantly during IP relative to EP, but intensity did not vary consistently across conditions. Without teaching or coaching, changes that occurred during IP did not carry over to EP produced immediately following IP within the same respiratory cycle.

Tight Junction-Related Barrier Contributes to the Electrophysiological Asymmetry across Vocal Fold Epithelium

Electrophysiological homeostasis is indispensable to vocal fold hydration. We investigate tight junction (TJ)-associated components, occludin and ZO-1, and permeability with or without the challenge of a permeability-augmenting agent, histamine. Freshly excised ovine larynges are obtained from a local abattoir. TJ markers are explored via reverse transcriptase polymerase chain reaction (RT-PCR). Paracellular permeabilities are measured in an Ussing system. The gene expression of both TJ markers is detected in native ovine vocal fold epithelium. Luminal histamine treatment significantly decreases transepithelial resistance (TER) (N = 72, p<0.01) and increases penetration of protein tracer (N = 35, p<0.001), respectively, in a time-, and dose-dependent fashion. The present study demonstrates that histamine compromises TJ-related paracellular barrier across vocal fold epithelium. The detection of TJ markers indicates the existence of typical TJ components in non-keratinized, stratified vocal fold epithelium. The responsiveness of paracellular permeabilities to histamine would highlight the functional significance of this TJ-equivalent system to the electrophysiological homeostasis, which, in turn, regulates the vocal fold superficial hydration.

Does botulinum toxin alter laryngeal secretionsand mucociliary transport

Localized botulinum toxin injection disrupts cholinergic transmission and has potential to cause focal dysautonomia. Mucociliary transport and laryngeal secretions are thought to be mediated in part by autonomic, cholinergic transmission. We questioned whether patients who receive Botox injection for adductor spasmodic dysphonia (ADSD) report postinjection symptoms possibly related to altered mucociliary clearance or laryngeal secretions. Medical histories, audiotaped interviews, and symptom ratings were retrospectively examined for 29 patients with ADSD who were followed after one or more Botox injections. Patients had received bilateral, percutaneous Botox injections of 2.5 units using an EMG-guided approach. One or more weeks after injection, four patients reported either burning, tickling, or irritation of the larynx/throat, excessive thick secretions, or dryness. Symptoms recurred with subsequent injections in two patients and were not associated with swallowing difficulty. These symptoms are consistent with, but not diagnostic of, the known effects of botulinum toxin on cholinergic, autonomic transmission.

MultiSensory Sound Lab for Educational and therapeutic applications

The MultiSensory Sound Lab electronically processes sound signals from microphones, musical instruments/recordings, electronic stethoscopes, and other sources and directs them to loudspeakers, a vibrating floor, and various large visual technologies that display the frequency, spectral, intensity, and time aspects of the signal. Originally developed for use with deaf children, the lab provides visual and tactile information about sound that is useful in a wide range of applications ranging from instruction in acoustics and physics of sound, to speech and music therapy for normally hearing, as well as, hearing‐impaired students. Example clinical and educational applications will be presented. Data from pre‐ and post‐testing show that sound lab activities result in significant concept learning and skill acquisition. User surveys shows that the sound lab eases teaching tasks and motivates students. Note: this presentation will serve as introduction to the MultiSensory Sound Lab tours that will be conducted a...

Noninvasive phonation threshold pressure estimates: Some methodological considerations

Phonation threshold pressure (PTP) is the minimum subglottal pressure required to initiate vocal fold oscillation. This pressure is important both theoretically and clinically because of its relationship to tissue viscosity, time varying glottal flow, and vocal tract acoustics. The effects of several different measurement methods on estimated PTP were studied in normal subjects. Oral pressures during quietly voiced consonant–vowel–consonant syllable strings were used to estimate PTP. Factors expected to impact PTP estimates included: (1) low nasal flows associated with soft, relaxed phonation, and (2) vowel context, due to possible reactive loading. A significant percentage of normal subjects evidenced low, inconsistent nasal airflow during /p/ occlusion near threshold (as indicated by nasal pneumotachography). Nasal flow was not associated with supra‐threshold production for these same subjects. In spite of similar instruction and pre‐recording practice, subjects varied in the strategies they used to accomplish phonation at soft levels near their threshold pressure. Strategies potentially involving slight adjustment in glottal adduction were observed and would be predicted to alter PTP. These methodological challenges will be discussed relative to the variability observed in PTP estimates, and the potential impact on validity and reliability of noninvasive oral pressure measurement.

Voice analysis of spasmodic dysphonia patients.

Adductor spasmodic dysphonia (SD) is a focal laryngeal dystonia resulting in closure spasms of the larynx during speech. Botulinum toxin (occulium A) injection into the thyroarytenoid muscle is currently used to temporarily ameliorate gross voice symptoms of this condition. Studies of subtle voice change are needed to describe and track the toxin effects. Aerodynamic, kinematic, and acoustic recordings of SD patients were obtained over a three‐month period. In one patient, glottal adduction immediately decreased after toxin injection and subglottal pressure steadily decreased over the three‐month period, suggesting an adaptation to reduced respiratory effort. The course of peak glottal airflow, maximum flow derivative, and glottal adduction show variations reflecting physiological and behavioral adjustments. Data for other subjects will be discussed. The significance of the study pertains not only to toxin effects on communication, toxin dose administration, and therapy concerns, but also to laryngeal fun...