**Abstract**

Underwater ambient noise is primarily a background noise which is a function of time, location, and depth. Background baseline of the noise in ocean is represented by ambient noise generated from the ocean surface due to wind and rain. This understanding pertained to ambient noise under various conditions will help in improving the signal-to-noise ratio (SNR) of marine instruments. It is of prime importance to detect the signals such as sound of a submarine or echo from a target surpassing this ambient noise. Ambient noise excludes all forms of self noise, such as the noise of current flow around the measurement hydrophone and its supporting structure. It should also exclude all forms of electrical noise. It is also defined as the residual noise that remains after all easily identifiable sound sources are eliminated. In the absence of sound from ships and marine life, underwater ambient noise levels (NL) are dependent mainly on wind speeds at frequencies between 100 Hz and 25 KHz.

**Keywords:** ambient noise, underwater, shallow water, wind noise, background noise
