This paper describes a sound reduction method of the traveling-wave sound from a duct end using a piezoelectric sound absorbing panel. A side-branch type or expansion-chamber muffler has been used to reduce the radiated sound; however, these silencers require additional large space. In addition, to add damping to those mechanical silencers is not easy. In contrast, the sound absorbing panel requires a minimal space. Furthermore, the damping of the panel can be tuned using piezoelectric elements. Because the mechanical impedance of the panel should be decreased to absorb sound effectively and widely, a method that reduces the mechanical impedance using another piezoelectric element and a microphone is additionally proposed in this research. The governing equations were theoretically derived, and the effectiveness of the proposed method was verified through simulations and experiments.
2016 一般社団法人 日本機械学会