A field experiment on the effect of sound absorption installed to a highly reverberant kindergarten classroom: A second report

Abstract

An experiment in a kindergarten classroom with an excessive reverberation was reported in Internoise 2022 and this is the second report of the continued experiment conducted in the same classroom. The classroom was highly reverberant (V = 200 m3, RT = 1.0 s at 1 kHz band) because the room was originally an outdoor space of ground floor pilotis and converted into a classroom by constructing concrete walls between the columns with the fire-resistant hard ceiling panels remained. The experiment was conducted by installing and removing sound absorbing materials on the walls and ceiling periodically for six months. The RT with sound absorber was reduced half at 0.5 s. The indoor activity was recorded by sound and video recorders. As a result, SPL of 1-2 kHz bands, which was regarded as children's voice during free play time reduced more than the direct effect of the sound absorption only when the sound absorption was installed first time. The SPL of 1-2 kHz when children singing together, which was assumed as voices without communication in contrast to free playing, was analyzed and the trend was similar to those in the free playing time.