REFLECTION OF A SPHERICAL SOUND-WAVE BY AN INFINITE ELASTIC PLATE WITH AN AIR-BACK CAVITY

In this paper, the reflection of a spherical sound wave by an infinite elastic plate with an air-back cavity is theoretically investigated. A far-field expression in closed form for the reflected sound field wh ich includes the effects of the plate vibration excited by the surroun ding sound field is derived analytically. The energy ratio of the refl ected sound wave by an infinite elastic plate to that by an infinite r igid immovable plate is defined. The ratio is found to take the same f orm as the energy reflection coefficient of an air-cavity backed infin ite elastic plate which the authors have previously derived in the cas e of a plane wave incidence. This is to say that the effects of the pa rameters relating to the sound reflecting system should appear in the same manner as in the case of plane wave incidence. The effects of the cavity on the sound reflectivity, which is a dip due to the resonance of mass-spring system consisting of the plate and the cavity and dips due to the acoustic resonance of the cavity, are discussed in detail.