Acoustic transfer functions coupled with a rear seat structure of sedan type vehicle

Abstract

Excellent quietness of passenger compartment of vehicles is demanded for vehicles with low interior noise such as electric and hybrid vehicles. Therefore, the investigation of acoustic transfer function of passenger compartment of vehicles is required to increase these quietness. The coupling effects between passenger compartment and trunk of vehicles affect acoustic response of the passenger compartment at the low frequency in sedan type vehicle. Air leakages and vibration of poroelastic materials of a rear seat between the cavity and the trunk are also known to affect acoustic response of the cavity at the low frequency. However, most studies of the coupling effects between the cavity and the trunk do not consider the influence of poroelastic materials of a rear seat between the cavity and the trunk. In this study, we investigated acoustic transfer function of the cavity of vehicles that is affected by poroelastic materials of a rear seat. The experimental results showed that poroelastic materials reduce the acoustic response of the cavity at low frequencies and change the coupled natural frequencies. The calculated results showed that poroelastic materials of rear seat can be modeled by Biot's theory. The calculated results also showed that poroelastic materials of a rear seat can be modeled by elastic materials if there is no air permeability. Then, theoretical study is made using a one-dimentional mathmatical model. The features of coupled natural frewuencies could be explained by this model.