Influence of absorption materials on the sound quality in a car

Recent automotive industry, passengers are not satisfied with simply being the car interior noise reduced, but demand to hear better sound in the car. In order to reduce the noise of the engine the sound absorbing material and sound insulation material has been used for long time bee used. However, this material should be optimized for the noise control and the minimization of fuel consumption. In this study, we have investigated the relationship between sound quality and sound-absorbing materials based on signal processing and acoustic ray. At the first, the impulse response functions from engine to dash and from dash to driver's ear position are calculated using ray tracing method. In the second, two impulse response functions are convolved by engine noise signal to yield the interior noise. The interior noise are used for the subjective test and for the calculation of sound metric. The correlation between subjective test and sound metric are estimated and used for the production of sound quality index according to absorption materials. The experimental method is also performed for the validation of index. The index will contribute to saving test time and developing a good performance sound-absorbing material.