Mitigation of noise in nursery school classrooms by sound absorption, Part 2: a year-long field experiment in actual classrooms

摘要

Following the previous report in Internoise 2011, a field experiment had been continued forrna year to investigate the effect of sound absorption on the comfortable acousticrnenvironment of nursery school classrooms. Sound absorbing boards, made of polyester,rnwere installed on the ceilings of the classrooms of an actual nursery school with their coverrnratio to the ceiling area being set to 0, 40 or 80 %. Noise levels were measured in the threerntime periods of lunch, reading and napping. The result indicated that the noise levelsrndecreased in various combinations of the sound absorption conditions and that the levelrndifference between 0% and 80% were 6-8 dB in some of those cases, which is greater thanrnthe expected physical reduction (approx. 3dB) estimated from the absorption coefficient ofrnthe board. Personnel of the school were asked to evaluate the indoor environment of thernclassroom and the answers were generally in favor of the absorbed conditions.