The Measurements and Evaluations on the Configurations of Absorptive and Diffusing Treatments in Classrooms using a Scale Model

초록

The present study examines the effects of periodic type diffusers for producing the preferred acoustics for speech and determines the more successful configurations of sound-absorbing and diffusing treatments for achieving good acoustics in classrooms. The measurements were carried out in a 1/10 scale model classroom systematically adding diffusers to one or more of four surfaces of the room. A total of 13 combination of diffusers with absorptive treatments were investigated. Adding diffusers on the ceiling were more effective to increasing the early-arriving reflection energy(G50) than adding absorptive materials on the entire ceiling. The late arriving reflection energy(Glate) was decreased with increasing amounts of diffusing treatments of upper front or rear wall and this resulted in achieving higher early-to-late ratios(C50). Adding diffusers on the upper front wall(AC100DUFW26) achieved more uniform acoustical conditions over the receiver positions than adding diffusers on the upper rear wall(AC100DURW26). Adding diffusers on the ceiling and absorptive materials on the lower front wall(AC75DC25ALFW26) achieved better acoustical conditions than adding the absorptive materials on the entire ceiling and lower front wall(AC100ALFW26).

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