Research on new techniques of multi-chamber mufflers equipped with a side inlet and internal nonperforated intruding tubes has been discussed in recent literature; however, the research work of multichamber mufflers in conjunction with side inlet and open-ended perforated intruding tubes which may efficiently increase the acoustical performance has been neglected. Therefore, the main purpose of this paper is to optimize the best design shape of multi-chamber side mufflers with open-ended perforated intruding tubes within a limited space.

In this paper, the four-pole system matrix in evaluating the acoustic performance is also deduced in conjunction with a simulated algorithm (SA). Results reveal that the maximum sound transmission loss (STL) is precisely located at the desired target tone. In addition, the acoustical performance of mufflers conjugated with perforated intruding tubes is superior to those equipped with non-perforated tubes. Additionally, the noise reduction ability for a three-chamber side muffler with a non-perforated intruding tube and a two-chamber side muffler with perforated intruding tubes are equivalent. Moreover, mufflers with more chambers will increase the acoustic performance for both pure tone and broadband noise.