A New Method of Characterizing Wind Noise Sources and Body Response for a Detailed Analysis of the Noise Transmission Mechanism 2016-01-1304

Interior noise caused by exterior air flow, or wind noise, is one of the noise-and-vibration phenomena for which a systematic simulation method has been desired for enabling their prediction. One of the main difficulties in simulating wind noise is that, unlike most other noises from the engine or road input, wind noise has not one but two different types of sources, namely, convective and acoustic ones. Therefore, in order to synthesize the interior sound pressure level (SPL), the body sensitivities (interior SPL/outer source level) for both types of sources have to be considered. In particular, sensitivity to the convective input has not been well understood, and hence it has not been determined. Moreover, the high-frequency nature of wind noise (e.g., the main energy range extends up to 4000 Hz) has limited the effective application of CAE for determining body sensitivities, for example, from the side window glass to the occupants’ ears.

This paper presents a new approach to the analysis of wind noise which has been restricted by the intrinsic nature of the noise sources (i.e., a mixture of convective and acoustic components). To cope with this dual-input complexity, a new transmission model was built to treat noise sources characterized simply as “forces” impinging upon the body surfaces regardless of the type of source and noise transfer functions (NTFs) employed as body sensitivities to the forces. This model enables a quantitative synthesis of interior noise and also a contribution analysis of the sources and/or body sensitivities with high accuracy.