EX_NR&amp;TL

# EX_NR&TL - ARC 4620 Environmental Technology 2 Lab...

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ARC 4620 Environmental Technology 2 Lab Session: Acoustics Sep. 16, 2003 NOISE REDUCTION (NR) & TRANSMISSION LOSS (TL) Noise Reduction (NR) is dependent on the three basic factors listed below. 1) Area of wall transmitting sound (S in ft 2 ) 2) Absorption in receiving room (a in sabins) 3) Transmission loss of dividing wall or barrier (TL in dB) a 2 : total room absorption after treatment (sabins) a 1 : total room absorption before treatment (sabins) a = Σα A: total absorption in receiving room (sabins) A: area of each surface (ft 2 ) α : absorption coefficient S: surface area of dividing barrier (ft 2 ) A rectangular room measuring 30’ x 20’ x 10’ (high) with highly reflective surfaces ( α walls =0.05, α floor =0.03, α ceiling =0.03) is found to be quite noisy. Determine the noise reduction if its ceiling is treated with a sound absorptive material ( α ceiling =0.65). Solution : We are using the first equation above. a 1 = Σα A = α walls A walls + α floor A floor + α ceiling A ceiling = 0.05(1000) + 0.03(600) + 0.03 (600) = 86 sabins a 2 = Σα A = α walls A walls + α floor A floor + α

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## This note was uploaded on 08/27/2011 for the course ARC 4620 taught by Professor Staff during the Fall '08 term at University of Florida.

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EX_NR&TL - ARC 4620 Environmental Technology 2 Lab...

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