Evaluation of a hard-walled rectangular room model with a planar absorption cavity

This study evaluates an approach to providing absorption to a hard-surfaced rectangular room. The concept is that planar cavities are established behind each room surface, with narrow openings to the room around their edges. While there is some potential for tuning such cavities to the axial and tangential modes of the room, such precise tuning may be impractical – so we examine the broad effect of this approach. The concept is evaluated in a scale model room by measuring and comparing the transfer functions between fixed transducers (in room corners) for various interventions, using a single planar cavity. Interventions include the size of the opening around the edge of the planar absorber, the depth of the planar absorber, and the presence or absence of resistive material within the plane.