Abstract
In an actual environment like in a factory, it seems very difficult to estimate only sound noise fluctuation emitted from an objective machine because of contamination by background noise from other working machinery. On the other hand, it is usual that factory noise emitted from a working machine shows various type non-stationary properties as a result of the diversified working situation(e.g., ON/OFF operation and/or fluctuation of loads) with lapse of time. In this paper, an effective evaluation method of the objective noise has been proposed through its related vibration acceleration level measurement to eliminate in principle the effect of background noises. Though, in general, the theoretical analysis on an acoustic emission caused by a mechanical vibration seems very difficult in a real working situation, a stochastic evaluation method derived on the basis of a generalized type regression analysis between mechanical vibration and its emitted noise levels has been employed to evaluate only the emitted noise. Furthermore, the non-stationary property of noise fluctuation related to rapid change of operation and etc. has also been evaluated on the basis of the probability of occurrence on each of locally stationary state. Finally, the effectiveness of proposed method has been experimentally confirmed by applying it to the noise evaluation of a non-stationarily operated jigsaw.
