Identification and Analysis of Dolphin Signatures from Ocean Ambient Noise Measurements

This paper presents identification of dolphin sound emissions from the ocean ambient noise measurements in the shallow waters of Arabian sea, off the west coast of India. Dolphin sound can be classified into broad band clicks and narrow band tonal sounds referred to as whistles. In this work the time series analysis performed on the noise measurements, reveal the presence of dolphin signatures and the type of signatures it produces. The time series shows the occurrence of dolphin clicks . Spectral analysis is carried out to determine the frequency contents. Since Fourier transform does not provide information on temporal component, short time Fourier transform is applied for time frequency analysis which enables time frequency representation of spectral components. The spectrogram shows burst of clicks emited by dolphins that are broad band in the range till 40 kHz Improved time localization is achieved by applying Gabor representation for time-frequency analysis.