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This paper presents a hybrid method that predicts the whistle occurrence of an automotive exhaust tuning device. The method utilizes inputs from a limited amount of test work or numerical simulation to predict the whistle occurrence in a wider range of flow conditions (temperature and velocity). It has the advantages of being quick and low cost compared with extensive tests or the computational fluid dynamics approach.

The definition method and the two load/source method of a transmission loss test of an automotive tuning device are discussed in this paper. For the definition method, the accuracy penalty due to the imperfect anechoic termination quality is studied based on an empirical acoustic model of glass-wool and the best practice of constructing an anechoic termination is attempted. The conclusion is verified with numerical simulations. For the two load/source method, the difference in the two source/load impedances compounded with the error of measured acoustic pressures, as related to transmission loss accuracy, is discussed and demonstrated.