A Study of NVH Vehicle Testing Variability

At certain key stages in the vehicle development process, prototype vehicles are available for NVH testing. This testing fulfills two functions: primarily it is used to assess the status of the vehicle to the program NVH performance targets, but it also provides an opportunity to validate the vehicle SEA model. These single vehicle test events provide a snapshot of the NVH performance but do not provide any understanding of the variability of the NVH performance, which is due to many factors: components, build or assembly and test setup variability. SEA models can be used to estimate the vehicle level variability, if the variability of the interior components is understood, but there is limited data available to confirm the accuracy of these predictions. In this paper we examine the repeatability and reproducibility through a standard gage R&R study of Engine Noise Reduction (engine NR) and Tire NR testing. We also examine the variation in NR from vehicle-to-vehicle through testing on six compact sedans of the same vehicle line. A more limited chassis dynamometer study on three of the six vehicles is also presented to look at typical running vehicle measures such as articulation index, loudness and overall SPL for tire and powertrain noise. Although the sample population is small, we have extracted estimates of variation in body noise reduction due to test setup, actual component and build variation and the implications for predicting variability through SEA models.