| 摘要 |
PURPOSE:To facilitate the preparatory work of measurement, and eliminate the waste of equipment, and eliminate the diffraction of the sound wave at the upper edge of the sample to obtain the accurate sound absorbing coefficient. CONSTITUTION:A sample, which is made of the building material having a predetermined shape dimension, is placed in a reverberation chamber 31, and the sound emitted from a speaker 36 inside of the reverberation chamber 31 is received by microphones 39 provided at plural parts inside of the reverberation chamber 31, and the sound absorbing coefficient of the sample is obtained on the basis of the reverberation time of the received sound. A pit 1 is provided under a floor 34, on which a sample 45 for the reverberation chamber 31 is to be placed, so as to have an opening 1a having a predetermined shape and dimension. A pair of legs 3, 4 to be opened and closed by a cylinder 8 are provided in the bottom part of the pit 1. A cover plate 11, on which top surface 11c the sample 45 is placed directly or indirectly, is made of the same material with the floor 34 of the reverberation chamber 31 and formed into a predetermined shape and dimension so as have a thickness as same as the floor 34 of the reverberation chamber 31, and this cover plate 11 is elevated by the legs 3, 4 inside of the pit 1. |
