Development of a rig test to measure transmission loss of air intake systems

The main functions of the air intake system are: supply air to the engine, filter particles, tuning the dynamic performance and filter acoustic noise. The last function can be characterized using parameters which will describe the performance of a general acoustic system. This includes: Noise Reduction, Insertion Loss and Transmission Loss. Among them, the transmission loss is a property of the acoustic system that represents the difference in the sound power level between the incident and transmitted waves. To measure the transmission loss in a simple and practical way, a rig test is proposed using an improved anechoic termination whose results presents a good agreement compared with analytical data. To validate the methodology, a simple expansion chamber with common dimensions is used as an acoustic element.