A study of engine noise transmission using statistical energy analysis

Abstract

This work uses statistical energy analysis (SEA) to study engine noise transmission through a small passenger motor vehicle and in order to do this the sound and vibration power input is calculated. An aim of this work is to identify the causes of differences between measured and SEA predicted vibration transmission in motor vehicles. To allow this to be studied a relatively simple running condition and vehicle are chosen. Airborne and structural paths for sound and vibration transmission to a vehicle saloon are considered. Also, SEA is used to identify the relative importance of each structural and airborne power input in relation to the sound power that is transmitted to the vehicle saloon. This technique can then make it possible for the power input matrix to be greatly simplified. The most important power input to the small passenger vehicle used in this study is found to be at the floor mounts of the engine subframe. At high frequencies resonant transmission through the firewall (dash) can also be important. The results indicate the difficulty of estimating the power input, which is the main cause of differences between measured and predicted results (even for the restricted running condition considered here). The work also demonstrates that SEA can be very useful for identifying important transmission paths and predicting overall performance.