Application of wavelets to the pre-processing of underwater sounds

In this paper we consider data on underwater sounds of differing types. Our objective is to filter background noise and achieve an acceptable level of reduction in the raw data, whilst at the same time maintaining the main features of the original signal. In particular, we consider data compression through the use of wavelet analysis followed by a thresholding of small coefficients in the resulting multiresolution decomposition. Various methods to threshold the wavelet representation are discussed and compared using recordings of dolphin sounds. An empirical modification to one of them is also proposed which shows promise in better preserving certain structures in our particular sound data.