Seat dip effect: The phenomena and the mechanism

Abstract

The phenomenon of excess attenuation due to audience seating, which is called “seat dip effect (SDE),” have been discussed in the case of a rather short-time interval including a direct sound and early arriving sound. However, it may be expected that the effect is diminished as the time interval increases, owing to the supplement of other arriving sounds. The first aim of this investigation is to clarify the effect of time interval on the SDE as well as the effect of other arriving sounds, by means of 110-scale model experiments. For the mechanism of the phenomenon, a clear explanation has not yet been given. The second aim is to clarify the fundamental mechanism of the SDE. For this aim, a wave-scattering theory for a periodic surface and a simple wave reflection theory for a layered boundary surface are applied, and discussed in comparison with the experimental results. From this investigation, it became clear that the mechanism of the SDE can be easily explained by using these simple analytical models.