Quadratic residue diffuser-resonator (QRD- R) N7: Design development of QRD using Helmholtz resonator as a well

Noise is a sound that occurs at incorrect time and place so being a nuisance for human activity. Many efforts have done to try to control the noise. One of them using acoustic material called QRD. QRD is a panel consider of wells with different depth to diffuse the reflected sound. The depth of the walls is calculated by DR. Manfred Schroeder formula. In this research, given a new design combination of QRD with resonator, we call QRD-R. The design consist of N7 QRD panel 35 cm x 35 cm using 5 cm x 35 cm Helmholtz resonator as wells' ground. The purposes of this research are looking for the effect of QRD-R into SPL distribution and attenuation. The result shows there is attenuation in some frequency and there is diffuse effect because of the diffuser.