Partial coherent excitations make the transfer path analysis (TPA) of road noise more complicated than the TPA of engine noise. In this research, a backward-multiple reference strategy is used to solve this partial coherent problem. First, the decoupling of multiple references is achieved by principal component analysis (PCA). Then, several backward-single reference TPAs referring to the principal components are performed to obtain the contribution of each path in the principal component space. At last, the total contribution of each path is obtained in the form of energy summation. This backward-multiple reference TPA is used to analyze the road noise of a prototype vehicle and the advantage of this method is presented in details. This method can not only be used to diagnose road noise problem, for example drumming noise, but also be used to lay down an excitation force standard.
