A field experiment on the effect of sound absorption on acclimation of new children to kindergarten—Part 1: Analysis of crying children and indoor noise levels

A field experiment was conducted where sound absorbing materials were temporarily installed in actual kindergarten classrooms to examine the effect of sound absorption on acclimation of new children to kindergarten. There were two classrooms for two 2-year-old groups and sound absorbing material was temporarily installed in one of the two rooms in April, beginning of the school year in Japan, and removed and re-installed in November. By the installation, the reverberation times in the 1 kHz band of the two rooms, which have different room dimensions, were reduced from 0.6/0.8 s to 0.4/0.5 s. The indoor activities were recorded by sound and video recorders. As a result, the time ratio of children’s crying during morning gatherings in April was observed for six days, and the time ratio in the room without sound absorption was between 3%-93% in 5 days, whereas 10 % in one day with sound absorption. SPL in the two rooms were compared in the same condition without sound absorption in the both rooms in November, and the SPL in the room with sound absorption until November was lower by around 2 dB, indicating that the voice level was lower than the other room without absorption throughout.