Reducing seat dip attenuation

Strategies fur reducing seat dip attenuation in concert halls are considere d. It is shown that the dip is established 4 ms after the direct sound from the stage arrives at the listener. Sound scattered from the seats and floo r is the main cause of the dip. By controlling these very early reflections the attenuation can be reduced to below its subjective threshold. With thi s in mind, changes to the shape and impedance of the seats and floor are tr ialed using a boundary element model and a physical scale model. It is foun d that the seat dip effect can be rendered inaudible by introducing a l-m p it under the seats. Smaller improvements are produced by changing the imped ance of the seat squab. (C) 2000 Acoustical Society of America.