Utilizing Hollow-Structured Bamboo as Natural Sound Absorber

Abstract

Studies to find alternative low environmental-impact materials for acoustic absorbers are still progressing, particularly those originated from natural materials. However, most of the established works are mainly focused on the fibrous-type absorbers. Discussion on the non-fibrous-type absorbers is still lacking and this therefore becomes the objective of this paper. Use of bamboo by utilizing its hollow structure to absorb sound energy is discussed here. The normal incidence absorption coefficient was measured based on the length and diameter of the bamboo, as well as different arrangement of the bamboo structure subjected to the incidence sound, namely, axial, transverse, and crossed-transverse arrangements. The trend of absorption coefficient appears in peaks and dips at equally spacing frequencies. For all arrangements the peak of absorption can reach above 0.8. Introducing an air gap behind the bamboo shifts the peak absorption to lower frequency. Covering the front surface of the absorber improves the sound absorption coefficient for axial arrangement by widening the frequency range of absorption also towards lower frequency range. The transverse arrangement is found to have average absorption coefficient peaks of 0.7 above 1.5 kHz. By arranging the bamboo structure with crossed-transverse arrangement, the suppressed absorption peaks in normal transverse arrangement can be recovered.

Analysis of sound absorption of hollow tube absorbers

“…This indicates that sound energy is mainly dissipated inside the tubes after penetrating the front cover or before reaching the back cover of the fabric. This is also consistent with the results for bamboo materials discussed by Putra, Khair [27].…”

“…Reeds in both axial and transverse arrangements are good in absorbing sound with absorption coefficients above 0.9 due to the non-uniformity of its inner and outer side of hollow structure which result in greater frictional losses. This study was duplicated by Putra, Khair [27] using bamboo structures from a species, Bambusa Multiplex which had a relatively smaller diameter. In this paper, the same hollow tube-like structures were studied, utilising plastic materials from wasted lollipop sticks in an effort to reduce plastic disposal in landfills and eventually save the environment.…”

Potensi Limbah Kulit Singkong sebagai Alternatif Material Akustik Ramah Lingkungan

“…Pada penelitian terdahulu dihasilkan bahwa bambu berstruktur hollow yang dimanfaatkan sebagai peredam suara alami menunjukkan nilai koefisien serap bunyi di atas 0,8 dengan susunan aksial (Putra et al, 2015). Nilai koefisien serap bunyi yang lebih tinggi ditunjukkan oleh material akustik dari serat tandan kosong kelapa sawit dengan rata-rata sebesar 0,9 pada frekeunsi di atas 1 kHz pada sampel dengan ketebalan 40 mm dan 50 mm yang memiliki kerapatan sebesar 292 kg/m 3 (Or et al, 2017).…”

“…Pengembangan material akustik berbasis bahan alami telah dilakukan oleh beberapa peneliti sebelumnya, seperti ampas teh, bambu berstruktur hallow, dan serabut kelapa (Munifatuzzahroh et al, 2021b;Putra et al, 2015;Simanjuntak & Mahda, 2019). Berbeda dengan banyak penelitian sebelumnya, pada penelitian ini dilakukan investigasi efektivitas pemanfaatan kulit singkong sebagai alternatif material akustik ramah lingkungan.…”

Potensi Limbah Ampas Teh sebagai Alternatif Material Akustik Ramah Lingkungan

“…Bahan organik lain yaitu bambu berstruktur hollow yang dimanfaatkan sebagai peredam suara alami, menunjukkan nilai koefisien serap bunyi di atas 0,8 dengan susunan aksial (Putra, Khair, & Nor, 2015). Nilai koefisien serap bunyi yang lebih tinggi ditunjukkan oleh material akustik dari serat tandan kosong kelapa sawit dengan rata-rata sebesar 0,9 pada frekeunsi di atas 1 kHz pada sampel dengan ketebalan 40 mm dan 50 mm yang memiliki kerapatan sebesar 292 kg/m 3 (Or, Putra, & Selamat, 2017).…”