音響模型実験のための内装材・吸音特性のシミュレーション

抄録

The following two conditions should be simulated for the scale model experiment of room acoustics; (1) the sound absorption by air (medium condition), and (2) the sound absorption characteristics of the interior material (boundary condition). As for the condition (1), the sound absorption by air under normal room conditions can be approximately simulated by use of dry air on N_2 gas as the experimental medium gas in 1/10 scale model experiment. As for the condition (2), however, only a few data of the sound absorption coefficient of the absorbents for the model have been published hitherto, and in many cases, experiments have been carried out at the degree of simulation that only reflective and absorptive surfaces are distinguished. In this study, it has been examined to what an extent the simulation of the sound absorption characteristics of the interior material is possible in 1/10 scale model experiment. For that purpose, by reducing various kinds of sound absorption mechanisms (such as panel vibration, resonator, perforated panel, slit wall and porous material) to 1/10 scale, the reverberant sound absorption coefficient has been measured by use of the model reverberant room. As a result, it turned out that the simulation can be realised at fairly good accuracy over almost all kinds of absorbents. Fig. 1 shows the measurement system employed in this study. It is almost equal to the means for the full scale absorbents except that the frequency range is 10 times higher (800Hz〜40kHz). In these measurements, N_2 substitution method has been adopted to stabilize the sound absorption by experimental medium gas.