Abstract：Engine noise is the main noise source of passenger cars. Inner-dash insulator plays a very important role in obstructing engine noise transmission from engine to passenger compartment. According to the sound insulation test principle of insulation material using the reverberant room-anechoic room method, a simulation analysis calculation model for sound insulation performance of inner-dash insulators with EVA layer and PU one was built in LMS Virtual.lab. It was shown that the difference between the simulated results and test ones is 0.5dB~2dB within the frequency range of 315Hz ~ 2000Hz, the simulated results meet engineering requirements. Using the simulation analysis method and model, sound insulation values and sound insulation efficiencies of 12 types of inner-dash insulators were computed. The results showed that the insulator with EVA thickness of 2.5mm and PU density of 50kg/m3 has the maximum sound insulation efficiency; this insulator can be taken as the optimal design scheme of inner-dash insulators. This conclusion was verified with sound insulation test results of inner-dash insulators. .
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