Abstract
The fluctuation of Leq over a long time period is statistically evaluated by means of its probability distribution form under the condition of the noise level observation on dB scale without observing a whole shape of its fluctuation pattern. First, by considering the nonlinear relationship between a sound level and a sound intensity, the distribution parameter on the Leq is estimated from the parameters on noise level fluctuation obtained by usual observation and the sampling number of averaging operation on the Leq within a short time interval. The non-stationary property of the Leq is also evaluated by the statistics of each parameters over a whole observation period. Next, to reflect the correlation effect among instantaneous sound levels, the joint moment statistics of sound intensity which reflect various correlation properties among sound levels during the averaging time period are estimated by using the joint moment statistics of sound level fluctuation. Finally, the proposed method has been applied to actual environmental noises and probability distribution form of the Leq is theoretically established by using their statistics.
