Reducing seat dip attenuation

Strategies fur reducing seat dip attenuation in concert halls are considered. 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 floor is the main cause of the dip. By controlling these very early reflections the attenuation can be reduced to below its subjective threshold. With this in mind, changes to the shape and impedance of the seats and floor are trialed using a boundary element model and a physical scale model. It is found that the seat dip effect can be rendered inaudible by introducing a l-m pit under the seats. Smaller improvements are produced by changing the impedance of the seat squab. (C) 2000 Acoustical Society of America.