The effects of acoustical refurbishment of classrooms on teachers' perceived noise exposure and noise-related health symptoms.

OBJECTIVES: To investigate whether acoustical refurbishment of classrooms for elementary and lower secondary grade pupils affected teachers' perceived noise exposure during teaching and noise-related health symptoms. METHODS: Two schools (A and B) with a total of 102 teachers were subjected to an acoustical intervention. Accordingly, 36 classrooms (20 and 16 in school A and school B, respectively) were acoustically refurbished and 31 classrooms (16 and 15 in school A and school B, respectively) were not changed. Thirteen classrooms in school A were interim "sham" refurbished. Control measurements of RT and activity sound levels were measured before and after refurbishment. Data on perceived noise exposure, disturbance attributed to different noise sources, voice symptoms, and fatigue after work were collected over a year in a total of six consecutive questionnaires. RESULTS: Refurbished classrooms were associated with lower perceived noise exposure and lower ratings of disturbance attributed to noise from equipment in the class compared with unrefurbished classrooms. No associations between the classroom refurbishment and health symptoms were observed. Before acoustical refurbishment, the mean classroom reverberation time was 0.68 (school A) and 0.57 (school B) and 0.55 s in sham refurbished classrooms. After refurbishment, the RT was approximately 0.4 s in both schools. Activity sound level measurements confirmed that the intervention had reduced the equivalent sound levels during lessons with circa 2 dB(A) in both schools. CONCLUSION: The acoustical refurbishment was associated with a reduction in classroom reverberation time and activity sound levels in both schools. The acoustical refurbishment was associated with a reduction in the teachers' perceived noise exposure, and reports of disturbance from equipment in the classroom decreased. There was no significant effect of the refurbishment on the teachers' voice symptoms or fatigue after work.

A study of classroom acoustics and school teachers' noise exposure, voice load and speaking time during teaching, and the effects on vocal and mental fatigue development.

OBJECTIVES: The study investigated the noise exposure in a group of Danish school teachers. The aims were to investigate if noise posed a risk of impairment of hearing and to study the association between classroom acoustical conditions, noise exposure, vocal symptoms, and cognitive fatigue. METHODS: Background noise levels, vocal load and speaking time were measured on 35 teachers during actual classroom teaching. The classrooms were characterized acoustically by measurements of reverberation time. Before and after the workday, the teachers answered a questionnaire on fatigue symptoms and carried out two cognitive test tasks sensitive to mental fatigue. RESULTS: The average noise level during the lessons was 72 dB(A), but during indoor sports activities the average noise level increased 6.6 dB(A). Room reverberation time (range 0.39-0.83 s) had no significant effect on the noise level. The teachers were talking with a raised voice in 61% of the time, and the vocal load increased 0.65 dB(A) per dB(A) increase in the average lesson noise level. An increase in voice symptoms during the workday correlated significantly with individual average noise exposure, and a decrease in performance in the two-back test correlated significantly with individual average vocal load. CONCLUSIONS: Noise exposure in general classrooms posed no risk of noise-induced hearing impairment in school teachers. However, the results provide evidence for an association between noise exposure and vocal load and development of vocal symptoms and cognitive fatigue after work.

Classroom acoustics and hearing ability as determinants for perceived social climate and intentions to stay at work.

Background noise and room acoustics may impede social interactions by interfering with oral communication and other cognitive processes. Accordingly, recent research in school environments has showed that social relationships with peers and teachers are described more negatively in rooms with long reverberation times (RT). The purpose of this study was to investigate how RT and hearing ability (i.e., hearing thresholds [HT] and distortion product oto-acoustic emissions) were associated with school teachers' perceptions of the social climate at work and their intentions to stay on the job. School teachers (n = 107) from 10 schools that worked in classrooms classified by acoustical experts as "short RT" (3 schools, mean RT 0.41-0.47 s), "medium RT" (3 schools, mean RT 0.50-0.53 s), and "long RT" (4 schools, mean RT 0.59-0.73 s) were examined. Teachers who worked in classrooms with long RT perceived their social climate to be more competitive, conflict laden, and less relaxed and comfortable. They were more doubtful about staying on the job. Even if the teachers were generally satisfied with their work the results suggest that the comfort at work may have been further improved by acoustical interventions that focus on reducing sound reflections in the classrooms. Yet, due the study design and the novelty of the findings the potential practical significance of our observations remains to be evaluated.