3個のマイクロフォンを用いた音響特性計測法の開発

―エンジン吸気配管系と吸音材料への適用―

抄録

A measuring method for the transfer matrix parameters of acoustic systems by using 3 microphones is described in this report. The acoustic characteristics of engine intake systems are usually analyzed by the transfer matrix method. However, there are some intake subsystems for which there is still no adequate theoretical representation. By using the 3 microphones method, the matrix parameters of unknown systems can be determined experimentally. Furthermore, this 3 mirophones method was applied for measurement of the acoustic charastristics of sound absorbing materials. The propagation constants and the characteristic impedance of some materials were measured and compared with measured values by using the 2 microphones method