Mass-air-mass resonance for multiple leaf partition using perforated plate

In an exchange counter, a taxi cabin, and so on, there is a partition between the user and the staff to secure safety. In contrast, the partition prevents speech communication between them. Thus, it is necessary to decline the sound insulation performance of the partition for their comfortable communication. Therefore, we have proposed producing mass-air-mass resonances by applying multiple leaf partitions to decrease the performance. The partition needs to be comprised of very thin sheets and very thin air layers to cause resonances in the frequency range of approximately 500 to 2000 Hz, which is included in voice frequency. In this study, we have realized the sound insulation decline using perforated plates instead of very thin sheets. The formulae of the resonance frequencies were derived for triple or quadruple leaf partitions when using perforated plates as partition components. Moreover, we have verified experimentally that the resonances can occur in the frequencies calculated from the formulae.