PENGUKURAN KOEFISIEN ABSORPSI BUNYI DARI LIMBAH BATANG KELAPA SAWIT

Abstract

The measurement of the sound absorption coefficient of oil palm stem has been conducted. A stem of oil palm which is used in this research was processed into square boards with size of 23 cm x 23 cm as a test sample. The sample then was cut into 4 pieces which has the same size but the thickness is varied, i.e 3 mm, 6 mm, 9 mm and 15 mm. Measurement of the sound absorption coefficient of the samples was done using impedance tube method made of acrylic. The generated frequencies used were 125 Hz, 250 Hz, 500 Hz, 1000 Hz and 2000 Hz. The highest sound absorption coefficient obtained from this research is 1.175 mm-1 at 2000 Hz frequency. Meanwhile, the smallest sound absorption coefficient is 0.157 mm-1 at 125 Hz frequency. The sound absorption coefficient of the samples at low frequencies (125-500 Hz) is quite small compared to high frequency. The sound absorption coefficient of samples increases as the frequency is increased. The result of research at 125-500 Hz frequencies showed that the sound absorption coefficient of samples depends on the sample thickness. The sound absorption coefficient increases as the thickness of sample is increased.