A Statistical Analysis of Robust Cicada Noise Level

When cicadas are chirping loudly during the traffic noise measurements in summer, it is difficult to obtain the correct traffic noise level. In the previous study, there were few reports on cicada noise levels, and the reports showed that the levels were uncertain, for example, as the cicada noise reached around 56 dB in the forest. Our aim was to investigate the details of the noise levels of robust cicadas. We measured the sound pressure level of the cicada noise in a free field. In addition, they were measured some features; the noise waveform, body length, total length and weight. The waveform was estimated to the equivalent continuous sound pressure level (LAeq) at 1 m per a cicada, where the level was extracted while the cicada sounds violently. The measurement data included of the levels of 77 cicada noises for statistical analysis. The type of LAeq distribution was normally distributed, and the mean value was 73.1 dB (standard deviation = 3.5 dB). The cicada measurements were normally distributed for body length, total length, and weight. However, there were no correlations between the LAeq and body length in the scatter plot results.