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Determination of sound transfer coefficient and noise insulation capability of boron added cellulosic mixture
(2007) Çö?ürcü M.T.; Şahinkaya S.; Donduren M.S.; Do?an S.; Özdemir C.
Noise is an important factor affecting human health psychologically due to lack of performance, hearing failures, decreases in heart beats, physiologically due to higher brain liquid pressure and sociologically due to lack of communication. Especially in closed working areas, it has significant negative effects on the performance. Noise control in closed working areas is generally done with boron added cellulosic mixture sprayed on the structure or surfaces with required thicknesses. In this study, noise was generated with central frequencies of 31.5, 63, 125, 250, 1000, 2000, 4000, 8000 and 16000 Hz by using signal generator, which can be heard by human ear at medium or top levels. The generated noises occurred at various frequencies with various noise levels that were later calculated as 100 dB. However, ? values (sound transfer coefficient) for the measured absolute values and the NRCs (Noise Reduction Coefficient) for 250, 500, 1000, 2000, 4000, 8000 Hz frequencies, the most sensitive ones for human ear, were calculated. The material used in the study was so efficient for high frequencies. The NRC and ? value were respectively obtained as 0.34 and 0.38 for 3 cm thickness, 0.31 and 0.72 for 5 cm thickness.