From sound quality to the engineering of solutions for NVH problems: Case studies

The subjective quality of sounds is a topic of increasing importance in the automotive industry. The first consideration when dealing with a specific noise quality problem, is to describe the perceptual characteristics of this quality by means of jury tests or appropriate metrics. Once the problem is determined in terms of an appropriate Sound Quality description, an in-depth analysis of the underlying physical phenomena must be made and engineering solutions need to be proposed and validated. This involves the detailed analysis of the signal structure in the time, frequency and order domain and identifying the signal components critical to the relevant sound quality dimension, the correlation of the critical signal components to specific sources, noise or vibration transmission paths and vibro-acoustic system characteristics and ultimately the prediction of the effect of feasible modifications. The above procedure is reviewed for two typical automotive sound quality cases, being a road noise problem (broad-band signal) and the sound of a door-slam (transient signal).