»Predictions on Absorption and Scattering Characteristics of Acoustic Scatterers Modified with Micro-Perforated Panels

Schroeder Diffusers are one of the most widely used acoustic scatterers in which the scattering phenomenon is predictable due to the geometry of the diffuser, based on a particular mathematical sequence. It is possible to increase the amount of absorption by modifying the diffuser structure by means of adding perforated panels into the wells or narrowing diffuser wells. In room acoustics applications, diffusers are conventionally mounted to a wall or ceiling assumed to be rigid enough such that sound wave cannot penetrate through. This research proposes a new modification on these diffusers where the diffuser is not backed by a rigid surface; it is hung over a space instead and aims to model the absorption and scattering mechanisms enabled with the non-rigid backing by improving a previously introduced mathematical model. In the study, diffuser wells are terminated with micro-perforated panels (MPP). Inclusion of MPP introduces additional losses; hence, higher absorption can be achieved. However, the most significant absorption in this configuration is achieved below the first resonance frequency of the panel-air space system due to the existence of non-rigid backing.