RESUMO
Noise pollution has a detrimental effect upon the learning and attainments of school children. Poor acoustical condition and high noise levels can cause many problems for the instructors and students. The acoustical indices and conditions of classrooms are important factors in the learning achievement of students. The purpose of this study was to find the relations of noise levels in indoor/outdoor and acoustical conditions of classrooms. Noise measurements and acoustical indices of 244 classrooms in 90 random samples consisting of primary, secondary and high schools in Tehran were considered. It was found that the average equivalent noise levels inside classrooms and corridors, yards and street sides in teaching condition were 72 dB[A], 65.8 dB[A], 64.1 dB[A] and 64.5 dB[A], respectively. Deference between mean indoor LAeq and background noise level in teaching conditions [above 32 dB] indicates that outdoor district noise sources could not significant affect indoor noise levels [P = 0.521]. Comparison of means between equivalent noise level in classrooms of boy schools with girl schools showed a significant difference [P=0.0001]. For the case of classrooms in primary, secondary and high school this Comparison had a significant deference [P=0.0001]. Site selection, improving acoustic quality, controlling opening in doors and windows and educating noise reduction for studied schools were proposed