Rain Noise Reduction of Corrugated Rooftop Using Structural Modification Method

Lee, Hong Zhen (2020) Rain Noise Reduction of Corrugated Rooftop Using Structural Modification Method. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

Malaysia experiences heavy rainfall invariable throughout the year. Noise generated by rainfall can become unpleasant to the surrounding area depending on the surfaces which it falls. It becomes more disturbed when it falls on corrugated rooftop. Analysis has been carried out indicated that rainfall on the corrugated rooftop is a significant noise issue and the impact from rain noise can be categorized as the irritating noise-causing disturbance and annoyance. Noise level of rainfall up to 65dB (normal conversation) sound pressure on corrugated rooftop. Since human hearing range is preferred below 60dB (soft music). It is noticed that a lot of the buildings in Malaysia are often built with corrugated rooftop. It is in urgent need to seek for a solution to improve the design of corrugated rooftop and reduce the rainfall noise. In this analysis, experimental modal and spectral analysis are carried out to determine the dynamic characteristic. Total of 16 mode shapes are determined in impact testing. From spectral testing, highest sound pressure occurred at 125Hz to 315Hz frequencies range. By comparing and observing both analyses, the critical resonant frequency was determined at 150Hz which produce a high sound pressure value. Structural modification method was conducted to minimize the unwanted noise on corrugated rooftop under raining condition. By adding of 0.5kg mass modification can reduce the amplitude response. Theoretically, mass modification manages to reduce 28% of noise on tested corrugated rooftop. Prediction was completed using of testlab software.