[Determination of the acoustic climate inside elementary schools]

The evaluation of acoustic conditions in four elementary schools showed high levels of noise inside schools, especially in corridors. It refers mainly public schools, which generally are overcrowded. During breaks the most frequent noise level is 86 dB but in some parts of corridors approaches values 95-98 dB. During lessons the noise in corridors decreases to about 64 dB. However during physical exercises which take place in corridors the noise level in corridors increases up to 75-80 dB. In public schools the noise levels in corridors both during lessons and breaks are higher about 12 dB than in private schools. However during lessons in classrooms those differences are quite lower. The noise level during lessons depends mainly on number of pupils, subject of the lesson, year of schooling and period of duration of the lesson. Considerable growth of noise occurs in classes above 20 pupils and at initial and final period of the lesson. The most favourable acoustic conditions are in classes below 15 pupils but in classes above 20 pupils the noise levels increase average about 4 dB. In spite of common opinion the noise level is lower in classes with younger children than in classes with older children. In older classes the noise is higher average about 3 dB. The noise in classroom depends also on manner of teaching and type of tasks performed by schoolchildren. The work in group is noisiest (average more 8 dB than during lectures). It refers especially to gymnastics lessons during group games. In this case the noise levels usually are above 90 dB. However it was not observed significant differences in daily or weekly distribution of the noise level during lessons. Resultant daily noise exposure of schoolchildren during their school time is 80 dB (or sometimes 85 dB) in public schools and 72 dB in private schools. Average noise exposure in public schools approaches critical values accepted for hearing protection for adolescents during apprenticeship.