Vocal Ergonomics in the Workplace: Heating, Ventilation, and Air-Conditioning Method Influences on Vocal Comfort and Function

Purpose The purpose of this study was to examine the influence of the heating, ventilation, and air-conditioning method on voice function following a voicing task using ecologically valid offices, one with radiant HVAC and one with forced air. Method A total of 12 consented participants (6 women, 6 men) narrated a video in each of 4 environmental conditions in a within-between repeated-measures design. Acoustic data were collected with an ambulatory phonation monitor and perceived phonatory effort was determined following the voicing task. Data were analyzed using a within-between repeated-measures analysis of variance with significance set at α < .05. Results Perceived phonatory effort did not differ between environments; however, a significant difference in vocal amplitude between 2 trials was identified for the male participants and physiologically significant differences in vocal amplitude were identified for male and female participants. Conclusions The findings suggest that perceived phonatory effort may not be a sensitive measure of vocal function differences following a voicing task in ecologically valid office spaces despite significant acoustic findings. Future research should address longer exposure to environmental differences combined with a longer voicing task within ecologically valid work spaces as well as the recruitment of participants who have particular vulnerability to environmental perturbations.

Vocal Function and Upper Airway Thermoregulation in Five Different Environmental Conditions

Purpose Phonation threshold pressure and perceived phonatory effort were hypothesized to increase and upper airway temperature to decrease following exposure to cold and/or dry air. Greater changes were expected with mouth versus nose breathing. Method In a within-participant repeated measures design, 15 consented participants (7 men, 8 women) completed 20-min duration trials to allow for adequate thermal equilibration for both nose and mouth breathing in 5 different environments: 3 temperatures (°C) matched for relative humidity (% RH), cold (15 °C, 40% RH), thermally neutral (25 °C, 40% RH), and hot (35 °C, 40% RH); and 2 temperatures with variable relative humidity to match vapor pressure for the neutral environment (25 °C, 40% RH), cold (15 °C, 74% RH) and hot (35 °C, 23% RH). Following each equilibration trial, measures were taken in this order: upper airway temperature (transnasal thermistor probe), phonation threshold pressure, and perceived phonatory effort. Results Data were analyzed using repeated measures analysis of variance, and no significant differences were established. Conclusions The study hypotheses were not supported. Findings suggest that the upper airway is tightly regulated for temperature when challenged by a realistic range of temperature and relative humidity environments. This is the first study of its kind to include measurement of upper airway temperature in conjunction with measures of vocal function.

Do Vocal Warm-Up Exercises Alleviate Vocal Fatigue?

Vocal warm-up (WU) exercises of varying types and durations have been suggested as a way of improving vocal function. However, limited research has been conducted to assess the effects of vocal WU exercises on normal or disordered voices. This study attempted to manipulate vocal function, assessed by phonation threshold pressure (PTP) and self-perceived phonatory effort (PPE) at 3 pitches, in 8 young women who reported symptoms of chronic vocal fatigue. Predictions were that PTP and PPE would decrease after 20 min of vocal WU exercises, increase after 1 hr of loud reading, and decrease after 30 min of vocal silence. Furthermore, greater increases in PTP and PPE were expected when the loud-reading task was preceded by a placebo condition of vocal rest than by vocal WU exercises. Results failed to reveal statistically significant changes in PTP or PPE after any of the experimental tasks. High between-subject variability contributed to this result. Removal of 1 outlier from the sample resulted in a statistically significant difference for PTP across tasks, although post hoc pairwise comparisons failed to detect specific effects. Informal inspection of the data indicated that the most obvious difference was an increase in PTP after the loud-reading task at the highest pitch.

Dependence of Phonatory Effort on Hydration Level

In this study, a double-blind placebo-controlled approach was used to assess the relation between hydration level and phonatory effort. Twelve adult, untrained voice users with normal voices participated as subjects. Each subject received a 4-hour hydration treatment, a 4-hour dehydration treatment, and a 4-hour placebo (control) treatment. Following each treatment, phonatory effort was measured with a physiological measure, phonation threshold pressure (PTP), and with a psychological measure, direct magnitude estimation of perceived phonatory effort (DMEPPE). Summarizing the results across these measures, the findings indicated an inverse relation between phonatory effort and hydration level, but primarily for high-pitched phonation tasks. The findings for PTPs replicated those from an earlier study conducted without double-blind experimental manipulations (Verdolini-Marston, Titze, & Druker, 1990). Theoretical discussion focuses on the possible role of vocal fold tissue viscosity for hydration and dehydration effects, although direct measures of tissue viscosity are lacking.