Avaliação dos fatores de risco para distúrbios de voz em professores e análise acústica vocal como instrumento de avaliação epidemiológica

Abstract

Purpose: conduct a prospective study to analyze risk factors for dysphonia in teachers, associated with presence of vocal alterations. Method: one-hundred-and-two teachers (81 women and 21 men) were randomly selected from 11 schools in Piracicaba/SP, with mean age 42.48 years. A questionnaire covering aspects of the work environment and organization, vocal behavior, lifestyle and signs and symptoms of vocal alterations was applied. Acoustic analysis was performed and the dependent variables assessed were Fundamental Frequency and mean Vocal Intensity. There were associations between questionnaire variables and Fundamental Frequency, and mean Intensity. The following statistical tests were used: Chi-square, Fisher´s Exact Test and Odds Ratio calculation. Results: individuals of the male gender had less chance of presenting altered fundamental frequency of the voice than the female gender (p<0.0001). Teachers who had been teaching elementary II and middle school had less chance of presenting alteration in fundamental frequency of the voice than those who taught in (first grade) primary schools I (p=0.04). The environmental noise was significantly associated with alteration in mean voice intensity (p=0.02). Conclusion: factors such as female gender, teaching in primary school and exposure to work environment noise are considered risk indicators for voice disorders. KEYWORDS:

Impacto do sistema de campo livre dinâmico na voz do professor: estudo de caso

“…Furthermore, other studies show direct relation between the increase in mean loudness and the noise in classroom 3,7 .…”

“…Probably the lower occurrence of dry throat symptom related to the dynamic soundfield system may happened due the enhance of acoustic conditions, and the reduction of vocal misuse, because the dynamic soundfield system enable sound amplification and even distribution to entire classroom, in the same intensity to all students, without repercussion or reverberation 15 , therefore it does not require the increase of teacher's voice loudness to reach all students, common strategy in teachers 7,8 . These data are reinforced by the acoustic classroom features, where the noise level varied from 55 up to 85dB, surpassing the recommended level by NBR 10.152 from 1987 5 .…”

“…Literature quotes the association between the increase of sound pressure level and the fundamental frequency 26 . The decrease of loudness enable by the dynamic soundfield system use, that automatically adjusts the frequency and intensity of sound in order to reach all the students equally 14 , may have facilitated the teacher communication, decreasing the fundamental frequency, because the vocal effort may have decreased, and the fundamental frequency lower indicates the decrease of strain and muscle overload 7,24,25 . Thus, a study analyzing the perception of 12 teachers, mean time experience of 13 years in classroom, regarding the perceived changes between the teaching periods with and without the dynamic soundfield system use, showed 92% of teachers reporting the decrease of vocal strain the major benefit of the dynamic soundfield system 27 .…”

“…National literature shows most classroom do not reach the standard recommended by NBR 10.152 from 1987 2,3,5,6 regarding acoustic quality, and the noise level varies from 45 up to 102dB [1][2][3]6 in those places. Most teachers exposed to noise have vocal complaints, and there is correlation between the increase in environment noise level and voice loudness in teachers 3,7 . The increase of loudness may be the strategy used by the teacher, who do not have the knowledge about voice health and voice set, in order to be heard and understood by the students in noise environment 8,9 .…”

Analysis of teacher working environment: factors that influence the voice

“…These high noise levels induce a Lombard effect (19) : the teacher must rival the background noise and increase the voice intensity in order to be heard. So, noise affects the voice (20,21) intensity in teachers, and especially the one coming from the students. Also, acoustics in the classroom has an impact on the teachers' voice (14,22) .…”