An Interactive Approach to the Design of an Acoustically Balanced Vehicle Sound Package 2007-01-2314

Each time a new vehicle is developed, engineers face the challenge to develop the ideal sound insulation package. The goal is to attenuate powertrain, wind and road/tire noise from entering the vehicle while complying with cost, weight and packaging constraints. The design process is greatly facilitated if the engineer has effective tools to rapidly quantify how various sound insulation components contribute to the overall NVH performance of the vehicle.

This paper discusses how an interactive vehicle acoustical design tool can be developed that assists the designer in making rapid decisions as to how to balance the performance of the various sound package components. The acoustical design tool is unique for each vehicle, and must take into account design decisions such as type of powertrain, body style, and numerous other factors in order to correctly predict the performance of the total package. Any good modeling tool must also take into account inputs from a reasonable range of operating conditions.

A very good model for the acoustical behavior of the vehicle can be developed using data from measurements made while operating a sample vehicle at the target operating conditions. The authors will present a method for utilizing measurements together with some simple equations to predict the result when components of different designs are exchanged. The process of generating the needed data for this method from experiments on a vehicle is admittedly time consuming, if all of the possible design variations are to be considered. An alternative that the authors present in this paper is for the case in which a correlated Statistical Energy Analysis (SEA) model exists for the vehicle being considered [1]¹. A great time savings is realized when the same acoustical behavior information about the vehicle can be extracted by running analytical experiments in the SEA model. The authors assert that even if an SEA model must be developed from scratch and correlated, this approach is preferable over the experimental approach.

Once developed, an interactive design tool of the type being discussed has ongoing benefit to product development engineers by giving them a handy way to asses future design changes. If sound insulation components are later sacrificed in the interest of reducing vehicle costs or weight, the model can accurately portray the implication of the changes on sound levels in the vehicle. A case study is presented that demonstrates the use of this tool and its accuracy.