A practical procedure for vehicle sound package design using statistical energy analysis

Vehicle sound package has a substantial role in attenuation of vehicle noise for the purpose of improving interior comfort and reducing environmental noise pollution. In this paper, two approaches of absorptive design and multi-layer design are investigated to improve the performance of a sound package in automotive applications. For this purpose, the sound package of the engine compartment including hoodliner and dash insulator is studied. Furthermore, this paper proposes an experimentally validated prediction model through Statistical Energy Analysis (SEA) to evaluate the sound insulation of a vehicle body sound package. For this purpose, the research includes characterization techniques of sound package materials to determine intrinsic parameters of different layers required to develop a reliable SEA model. The inverse method and time-temperature superposition principle (TTSP) are utilized to characterize porous materials and heavy layer properties, respectively. The comparison of results that are experimentally obtained by acoustic cabin shows a fairly well agreement with the proposed SEA modeling procedure for the desired frequency range. By observing the results of the simulation for the hoodliner and dash insulator, it was revealed that the absorptive design combines the benefits of high sound absorption capability, wide absorption frequency band, and lightweight. Indeed, with an appropriate combination of layers, the multi-layer design can simultaneously provide a mixture of absorptive design attributes and sound insulation capabilities. The transmission loss obtained from the proposed design of the dash insulator revealed an increase by 42% without any reduction in the amount of sound absorption. Also, the sound absorption of the proposed hoodliner is enhanced more than twice in reference to the base design.