Numerical Investigation On Rainfall Noise Intrusion And Prediction Of Rain Noise For Different Composite Roof Constructions

Lee, She Jie (2008) Numerical Investigation On Rainfall Noise Intrusion And Prediction Of Rain Noise For Different Composite Roof Constructions. Project Report. UTeM, Melaka, Malaysia. (Submitted)

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Abstract

This thesis is focused on the numerical investigation on rainfall noise prediction for different composite roof construction for different rainfall rates, velocity and droplet size. Based from the previous reviewed on the theoretical considerations, a semi-empirical equation was developed to predict the noise level due to rainfall for a range of composite roof construction. For an assumed rainfall droplet size, rainfall rate and rainfall velocity that impacting on the roof panel and then transmitted into a reverberant room condition an empirical constant was proposed which allows the sound intensity level to be estimated. Theoretical studies were based on the concept and mechanism of noise generation on different composite roof installed and roofing material layers construction in an acoustic reverberation room. Basically, the composite roof were laminate the roofing materials to form a single layer of composite but as for roof construction, most of the time that consisted a bare roof and composite roof with different noise control options such that its effect on noise and vibration generated could be determined. Based on the theoretical for semi-empirical equation and the transmission loss, a new numerical prediction is formulated to predict the sound intensity level due to a range of composite roof layer. This numerical prediction was compared with previous works for purpose validation and it was found that the numerical prediction was quite accurate in terms of minimal error. The characteristics of the composite roof materials especially the density and the thickness may influence the transmission loss value. As the density and the thickness increased of the roof material being selected, more sound transmission loss will be obtained and therefore reduced the noise generated inside a room.

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