On the Estimation of the Noise Emitted by the Vibration of a Circular Plate (2nd Report)

Modern-day life is such that machines, equipment, and humans must function properly in mechanical vibration and accoustic noise environments. In addition to damage incurred directly, vibration may also result in the generation of undesirable accoustic noise, and the reduction of vibration may reduce noise level. So, it is important to make clear the problems concerning with the relation of vibration and noise. In the previous report, a method for rough estimation of the noise level by the radiation factor K was described. This report describs in detail the relation between the vibration of a circular plate clamped at the edge and the noise originated by the surface vibration. Assuming that the circular plate is consisted of many minute elements and each of them vibrates as a simple harmonic motion in an infinite baffle, then the sound pressure level at a point away from the plate surface is obtained by summing up all the sound pressure radiated from each minute sources. The values of the over-all sound pressure level calculated by this method have been found in good agreement with those obtained from the experiments.