Analysis and Design of Active Sound Absorption Muffler Based on Acoustic Electric Analogy

A design theory for an active muffler is proposed in this paper. This paper mainly introduces the structure, noise reduction process, working principle, and the active sound absorption principle of the active muffler. The working principle of the active muffler is based on active sound absorption theory. Two layers of polyvinylidene fluoride (PVDF) film are placed on the inner wall of the muffler, serving as piezoelectric sensors to detect incident and reflected sound waves, respectively. Additionally, a layer of piezoelectric ceramic is placed outside the sensors to act as an actuator. The piezoelectric properties of the material allow it to control the incident sound pressure signal, preventing reflection and thereby achieving active sound absorption and enabling the active muffler to function. MATLAB simulations were used to verify the feasibility of the proposed theory. Finally, a comparative experiment was conducted to evaluate the performance of the active muffler. The experimental results indicate that the active muffler achieves better noise reduction in the low-frequency range compared to passive mufflers.