Analysis of Short Term Temporal Fluctuations in Noise Power Spectrum of Shallow Water Ambient Noise

Abstract

This paper presents the results illustrating temporal fluctuations in the noise power spectrum level of shallow water ambient noise in the bandwidth of 100 Hz to 4 kHz by analyzing its statistical properties. Experiment was conducted to measure the shallow water ambient noise at 25 m depth for a period of 15 hours with an omni-directional hydrophone deployed at 5 m from the sea surface. The data were collected every hour for a period of 1 minute. Wind speed was also measured during the data collection and the variation in wind speed was between 1.5 to 2.5 m/s. The analysis result shows the variation in the average noise spectrum level was found to be higher in the lower (100 Hz to 1 kHz) and higher frequencies (3 kHz to 4 kHz) of the band and found to be almost constant in between.