On the Use of Coupled Cavity Helmholtz Resonator Inclusion for Improving Absorption Performance of Wooden Sound Diffuser Element

This study focused on the use of coupled multi-degree of freedom Helmholtz resonator inclusion for improving sound absorption of wooden sound diffuser element. Tubular shaped sound diffuser element was made from round waste wood from furniture industries. The multi-degree of freedom Helmholtz resonator was created through machining process for three different sound diffuser element diameter 4 cm, 6cm, and 8 cm. Laboratorytest measurement conducted using B&K impedance tube 4206 refers to ASTM E-1050 standard. The resultsshow that coupled multi-degree of freedom Helmholtz resonator inclusion works properly as expected. All model has promising performance in the mid to high frequency range between 500 Hz to 1 kHz. Even more, the bigger diameter gives a better possibility for shifting the sound diffuser element response to low frequency band below 500 Hz.