Engine Contribution Analysis Using a Noise and Vibration Simulator

We investigated a pure time-domain version of source-path-contribution analysis using a controllable source, a noise and vibration simulator installed into a trimmed vehicle. We examined both airborne and structure-borne inputs, and used the matrix method in the time-domain to calculate source contributions as sounds at a listeners' position inside the cabin. Operating data from a simulated run-up/run-down and sets of transfer functions (FRFs) are used first to estimate the strength of some defined point sources, both acoustically and mechanically. Second, the operating source strengths are combined with acoustic or vibro-acoustic FRFs to predict contributions at a receiver. Here we attempted to make the airborne and structure-borne models as simple as possible, and predicted contributions are validated against actual measured data. All measurements were conducted on the vehicle with and without the engine simulator installed.