Abstract: A substructure method and a dual reciprocity boundary element method(DRBEM) are applied to calculate four-pole parameters and transmission loss of ducts and silencers with complex flow.Basic principle and numerical procedure are introduced in detail.It is shown that the DRBEM is valid to compute four-pole parameters and transmission loss of ducts and silencers with subsonic complex flow with higher Mach number.The substructure method reduces numerical complexity of the DRBEM and improves accuracy and computation speed.

Key words: substructure dual reciprocity boundary element method, silencer, transmission loss, four-pole parameters