Skyline quadratic residue diffuser-resonator (SQRD-R): A study about its characteristic

To create a comfortable acoustic environment both indoor and outdoor, we need to control the noise. In the room, noise comes from both outside and inside the room for example is flatter echo. Installation of acoustic material such as absorber, resonator, or diffuser is an example of indoor noise control. QRD is one of diffuser consider of wells with different depth to diffuse the reflected sound. The depth of the wells is calculated by DR. Manfred Schroeder formula. In this research, a combination of Skyline QRD and Helmholtz resonator is given, we call it SQRD-R. This SQRDR follows the design from Wes Lachot Design but using a Helmholtz resonator as the cell. The examination of its characteristic is built using both of impedance tube test and calculation. The purposes of this research are learning about the effect of holes position on its sound impedance and sound absorption coefficient. The highest impedance value is -j(3.5 x 107) acoustic ohm. The highest absorption coefficient is 0.9. By controlling the SQRD-R dimension, we can control noise at specific frequency.