An evaluation method of Leq for noise fluctuation of non-Gaussian and nonstationary types.

Abstract

An Leq is usually calculated through an averaging operation of anti-logarithm of the measured instantaneous level value in a decibel scale. Considering the nonlinear transformation of level observation, there seems to remain a principal problem that the average energy can not be exactly obtained owing to the inequality of quantization width in an energy scale differing from the equality of quantization width in a level scale. In this paper, the averaged sound energy is estimated on the basis of level statistics with help of the moment generating function of sound level by considering the fundamental relationship between the sound level and its energy. Then, an evaluation method of Leq is derived in the series expansion form reflecting the stationary and Gaussian properties as the first expansion term and the correction term for the deviation from these statistical properties as the higher order expansion terms. Finally, the proposed estimation method is experimentally confirmed by applying it to the actual noise environment inside and outside a room.