**3.4 Rain noise**

Nicolaas Bom [8] studied the influence of rain on undersea noise level. Experiments were conducted in Italy at the lake of Sarzana near La Spezia. Data is analyzed between 300 Hz and 96 KHz. The observation and inference of this work reflected the effect of rain on noise, i.e., noise level increases w.r.t to increased rainfall rate. It was concluded that "it corresponded to higher frequency energy."

In 1986, Nystuen [9] reported that a light rain with total rainfall of <2.5 mm per hour produced a spectral peak at 15 KHz (broadband wind sensitive). And, a heavy rain where a total rainfall was more than 7.5 mm per hour produced a wideband noise ranging from 4 to 21 KHz. A similar type of study and data analysis was done by Deane [10] for a period of 1 year, and this work also revealed the effect of rain noise.
