Carga vocal de professores universitários: estudo exploratório

Abstract

Introduction: The intensive voice use under high noise levels and inadequate acoustics are risk factors for dysphonia. However, the safe limits for prevention are still unknown and the proposals for collective intervention are limited. Objective: verify the effects of vocal load in a large capacity classroom on the vocal quality of university professors. Method: exploratory, observational, longitudinal study, with a single group of subjects and primary vocal monitoring data for two weeks. Acoustic characterization of the classroom, auditory perceptual and acoustic evaluation of voice samples before and after and vocal dosimetry during classes were performed. The statistical treatment of the data consisted of descriptive analysis and randomization method, adopting the level of statistical significance of p<0.05. Results: the prevalence of voice disorders was 20%. All participants reported speaking loudly in class and the majority (80%) reported voice alterations in the last six months and voice related health problems. The unoccupied classroom presented equivalent sound pressure levels, varying between 55 dB and 57.3 dB. The reverberation times ranged from 1.12 s to 3.24 s (at frequencies from 250 Hz to 8000 Hz) and the speech transmission indices ranged from 0.31 to 0.38. The professors presented high vocal doses in the classroom with the use of high vocal intensity, ranging from 108.66 dB to 118.97 dB. In the descriptive analysis, there was an increase in the average, after classes, in the two weeks of the general CAPE-V score (4.6mm and 11mm), of jitter (0.08% and 0.01%), of the fundamental frequency of the vowel (7.2 Hz and 15.35 Hz) and connected speech (17.42 Hz and 8.7 Hz) and of the average (2.40 dB and 1.73 dB) and maximum intensity (1.79 dB and 1.59 dB). The averages of the Vocal Fatigue Indexes were outside the normal range, increasing in the second week (18 and 22.6). Significant differences were found in noise variables (before class between weeks, pseudo p value = 0.02) and maximum intensity (after class between weeks and between the beginning and end of the study, pseudo p-value = 0, for both). There was a significant correlation between phonation time and overall CAPE-V grade (pseudo p-value=0.02) and between distance dose and maximum intensity (pseudo p-value=0.02). Conclusions: the doses and the Vocal Fatigue Indexes were shown to be high, possibly impacted by the vocal demand in the classroom. The increase in the mean Vocal Fatigue Index in the second week may be due to the increase in the sensation of cumulative fatigue. CAPE-V can assist in the longitudinal monitoring of teachers in the work environment, helping to monitor the installation of a possible DVRT. The distance dose can be useful in vocal monitoring, and further studies based on it may provide data for the establishment of safe vocal doses for teachers. Further studies with larger samples and in an acoustically conditioned classroom are suggested, aiming to investigate possible relationships between demand, demand response, effort and vocal fatigue in different occupational contexts and provide data for collective interventions.