Errors in transmission loss prediction―the bispectrum and kurtosis approaches

摘要

The measurements of the acoustic performance of automotive mufflers are influenced by the wave propagation with reflection and absorption. This way, the measured signal can have linear and non-linear interactions of the wave components. The bispectrum, which is the measure of the phase relationship between three spectral components, has been shown to be a useful tool in the study of linear and non-linear wave interactions. The bicoherence spectrum may be used to discriminate between non-linearly coupled waves and spontaneously excited waves. At the same time, the kurtosis parameter is used as an indicative of the signals of microphones. The performances of two different physical models (bipartite chamber and a chamber with concentric perforated tube) are analysed considering the transmission loss. The experimental data are obtained through a two microphone method and the numerical values through the finite element method.