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A fully analytical method for the evaluation of noise reduction in a vehicle interior furnished with layered acoustic trim is presented. The method combines calculation of trim Transmission Loss (TL) and Absorption Coefficient with a Statistical Energy Analysis (SEA) calculation of trimmed panel Noise Reduction (NR). This allows for the evaluation of the trim package performance in real operating conditions and ranking of the different air-borne and structure-borne transmission paths.

Automakers have reported that passenger perception of vehicle interior wind noise is strongly correlated to the non-Gaussian and non-stationary character of the exterior aero-acoustic wind loading. Researchers in other domains have shown that leptokurtic non-Gaussian loading (Kurtosis κ>3) can be synthesized by non-stationary modulation of otherwise Gaussian random loading. This paper introduces a transient statistical energy analysis (SEA) model for the aero-vibro acoustic transmission of non-stationary wind noise which uses the same approach - a modulation of otherwise Gaussian random fluctuating pressure loading, in each one third octave band. The authors have previously shown that the non-stationary character of random wind loading can be measured in a wind tunnel or on the road with a suitable surface pressure microphone array.