1971 年 27 巻 3 号 p. 144-152
When room acoustics are analyzed by acoustical scalemodel the model room must be set to a situation equivalent to the actual room and to wall material of equivalent acoustic impedance, for the law of similarity between actual and its model room to hold. In the first place the author made use of the material of equivalent sound absorption coefficient instead of equivalent acoustic impedance. The author, therefore, made a model-reverberation room, and tried to find the sound absorption coefficient of the wall material in a 1/10 scale-model room. In order to reduce the sound attenuation due to humidity in the air in high frequencies, the author studied the law of similarity between reverberation time and reduction scale of the model, using the relation between reverberation time and attenuation coefficient due to humidity in the air. As the result, it has been proved that dehydration in model room is effective. Reverberation time was deter-mined by using a high speed tape recorder that recorded reverberation sound in the model room with dry air, and reproducing it by reducing the tape speed to 1/10. By way of example, the author made 1/10 scale-models of a chapel and a hall, and reported the results on the reverberation time, sound pressure response and echo pattern as compared with the actual room.