A critical review of some Panel Contribution Analysis methods used in interior vehicle acoustics 2024-01-2932

In the acoustic study of the interior noise of a vehicle, whether for structure-borne or air-borne excitations, knowing which areas contribute the most to interior noise and therefore should be treated as a priority, is the main goal of the engineer in charge of the NVH. Very often these areas are numerous, located in different regions of the vehicle and contribute at different frequencies to the overall sound pressure level. This has led to the development of several “Panel Contribution Analysis” (PCA) experimental techniques. For example, a well-known technique is the masking technique, which consists of applying a “maximum package” (i.e., a package with very high sound insulation) to the panels outside of the area whose contribution has to be measured. This technique is pragmatic but rather cumbersome to implement. In addition, it significantly modifies the dynamics and internal acoustics of the vehicle. In another well-known technique, the contribution of a certain area is defined based on the Kirchhoff-Helmholtz equation and evaluated by first measuring operational acoustic pressures and velocities (by means of PU-probes) and then measuring acoustic transfer functions, always keeping the vehicle in its serial conditions (i.e., without the need of any masking). The aim of this paper is to review, with the support of some numerical experiments, such methods used for panel contribution analysis, investigating in particular the assumptions and basic principles underlying their applicability. It is shown that, depending on the method, different interpretations and rankings can be obtained.