## 1 Introduction
Overall, a reasonable noise reduction result may be obtained in a certain frequency range by modifying the adversarial muffler's structural characteristics; however, this method is not applicable to scenarios with an extended frequency range. For the purpose of achieving wideband sound absorption capability from 640 Hz to 1410 Hz while guaranteeing smooth ventilation ducts, [PERSON] [26] implemented an inventive technique of inserting sound-absorbing materials into the inner wall of the expansion chamber muffler. The micro-perforated plate muffler combines the features of a resonant and resistive muffler. A broader noise reduction frequency range is produced by the tiny microporous structure's improved sound resistance. Simultaneously, the absorption peak's frequency is controlled by the cavity construction, which enhances the noise reduction effect. By altering the porosity of perforated materials, [PERSON] [27] conducted a preliminary investigation on the noise reduction properties of perforated silencers in vehicle HVAC systems. [PERSON] [28] established an ecologically friendly double-layer micro-perforated material muffler that may achieve stronger noise reduction characteristics under smaller-sized circumstances by combining the acoustic reflection expansion chamber with dissipative micro-perforated components. In the context of Helmholtz acoustic resonators [29], by creatively combining a Helmholtz silencer with a perforated plate construction, [PERSON] [30] was able to achieve excellent results in terms of the reduction in low-frequency sound noise. The three primary methods for managing noise are reducing noise sources, restricting noise spread, and enhancing receiver protection [31; 32]. The aforementioned indicates that pipeline muffler research has advanced significantly. Nonetheless, the majority of current research discloses the noise reduction capabilities and sound propagation properties of mufflers by focusing on the plane wave theory-based transmission loss prediction model. The study effort has taken factors that impact noise reduction performance into consideration, such as the shape of the pipeline cross-section and the installation of sound-absorbing materials. In actuality, there is a cavity resonance mode in expansion-type mufflers because, when the frequency rises, the sound wave in the muffler pipeline is not a perfect plane wave. It is obvious that the plane wave-based transmission loss model of pipeline mufflers is unable to accurately represent the muffler performance. Consequently, the acoustic cavity mode of the expansion muffler will be analyzed using the finite element approach in this article in order to uncover the transmission loss underneath its acoustic cavity resonance. Using a sound pressure level diagram, investigate the acoustic properties of a short-cavity expansion muffler and suggest a dual-cavity composite pipeline muffler construction. Potential engineering uses for this research include noise control in air conditioning pipes. The article is organized as follows. The research is summarized in Section 4 and covers the following topics: Section 2 examines the transmission losses and acoustic resonance modes of pipeline mufflers and Section 3 examines the acoustic model, resonant modes, and the impact of sound-absorbing materials on the noise reduction performance of a dual cavity composite air duct muffler.