Acoustic properties of a cavity backed stage floor: A theoretical model

This paper analyzes the effect of an excitation force from a string instrum ent on the acoustic properties of a stage floor. The theory [9] Nakanishi S , Sakagami K, Daido M, Morimoto M. Effect of an air-back cavity on the refl ected sound held of a spherical sound wave by an infinite elastic prate dri ven to vibration by a point force. Applied Acoustics, in press., for a sphe rical wave reflected by an air-cavity backed elastic plate driven into vibr ation by a point force, is modified. A measurement of an excitation force, exerted from a violoncello into a wooden riser, is performed. The numerical examples with the measured force demonstrate that the effect under conside ration is significant at some frequencies. The modified theory explains the phenomenon called resonant support which is caused by the sound wave refle cted by a rigid floor and the sound wave radiated from the riser top. (C) 1 998 Elsevier Science Ltd. All rights reserved.