All surfaces of a cabin interior may contribute to the sound pressure at a certain reference position, e.g. the human's ear. Panel noise contribution analysis (PNCA) involves the measurement of the contribution of separate areas. This is an effective method to determine the effect of apparent noise sources at a specific location.
This paper presents the latest developments on particle velocity based panel noise contribution analysis. In contrast to the traditional methods, the particle velocity approach is faster; it requires 3 days instead of weeks. While the theoretical base of the procedure in this paper is similar to previously published particle velocity based procedure, here the measurement protocol has now been simplified dramatically, which has reduced the measurement time even more to less than a day. The method and its implementation are explained in the paper and a full measurement procedure is reported.
Four steps are required to determine and visualize the pressure contribution of the vehicle interior.
In a first step, probes are positioned on predefined interior surfaces. Special probe mounting have been made to decrease the handling time.
The second step is a measurement in a certain mode of operation. This step can be done in a laboratory but it is also possible to perform the measurement whilst driving the vehicle on the road. Stationary as well as non stationary running conditions like run ups are accessible and do not limit the applicability of the method.
The third step is the determination of the transfer paths from the panels to a certain listening position. This measurement is done assuming reciprocity. A monopole source is placed on the listener position and the sound pressure is measured at the surface.
In a fourth and last step the transfer paths are linked with the operational data gathered in step two. The results are then visualized using the predefined geometry model.
This paper describes the measurement of a conventional car with a resolution of 137 panels. Since an array of 46 probes was used step 2 and step 3 are repeated 3 times.