Optimized muffler design and its performance evaluation to environmental noise reduction on classrooms

Abstract

Generators powered by diesel engines are widely used as a backup source of electrical energy. However, the generator produces very high noise, which is around 73–110 dBA. In this study, we designed a muffler and optimized to the highest possible noise reduction. We constructed and installed the designed muffler to evaluate the performance an absorptive muffler on the exhaust pipe of the simulated muffler with the installed one. We measured the sound pressure level (SPL) at the source of exhaust gas noise before the proposed muffler installed and after installation, including inside the surrounding classrooms. A survey was also conducted to determine the annoyance response of the teachers and the students. The results show that the presence of an absorptive muffler can reduce noise by 10 dBA and attenuate more at high frequencies (<500–16000 > 500–16000 Hz) at the source of the noise and also in the surrounding environment. The annoyance rating for generator exhaust noise is moderate to very disturbing for listeners who are outside the room and moderate for listeners positions in the room.