Pengaruh Ketebalan Spesimen Terhadap Kemampuan Menyerap Bunyi Pada Kombinasi Serat Sabut Kelapa (Cocofiber) dan Serat Ekor Kucing (Typha Latifolia)

Abstract

This study aims to determine the effect of the thickness of the test specimen by combining coco fibers and typha latifolia fibers on the value of the sound absorption coefficient (SAC) and sound reduction coefficient (NRC). In this study, 3 test samples were made where each sample consisted of coconut coir fiber weighing 25 grams and cat tail fiber weighing 25 grams with a thickness of 10 mm, 20 mm and 30 mm, the samples were arranged in layers and then pressed on a hot press with temperature 200 C. The sound absorption coefficient test was carried out using an impedance tube with the transfer function method (ISO 10534-2:1998) at a frequency of 1/1 octave. The test results show that at a frequency of 125 Hz - 1000 Hz the value of the sound absorption coefficient increases with increasing frequency, the maximum sound absorption value of 0.684 occurs at a frequency of 1000 Hz at a thickness of 30 mm, followed by a thickness of 20 mm 0.6568 and 10 mm 0.6304, but at a frequency of 1000 Hz – 4000 Hz the value of the sound absorption coefficient decreases to 0.61  The combination of the two fibers can reduce the noise level to 0.542 (54.2%) at a thickness of 10 mm, 0.565 (0.56.5 %) at 20 mm and 0.603 (60.3%) at 30 mm. It can be concluded that the thickness of the test sample can affect the sound absorption value, the thicker the test sample, the greater the ability to reduce noise.