Ultrasonic signal denoising based on wavelet haar decomposition level

In the era of technology, signal transmission or signal recording is inseparable with the advent of noise. This study aims to eliminate noise (noise) on the ultrasonic signals to dolphins recording voice, as well as to determine the level of decomposition and the best kind on wavelet threshold with evidentiary value of SNR (Signal to Noise Ratio). Haar wavelet type is used in this study. One of the uses of wavelets is, it can be used for noise reduction in non-stationary noise signal. Reduction of noise on the voice signals using wavelet is done by filtering with the operation of sub-sampling which passes the signal through the low pass filter and a high pass filter which is called the level of decomposition, wavelet coefficients will be obtained, then perform threshold (skip at certain threshold) of the wavelet coefficients so that noise can be reduced. Threshold used is hard threshold and soft threshold. The results obtained by the best value of SNR (Signal to Noise Ratio) is at the level 5 of decomposition with an average value in soft threshold amounted to 46.5548 dB, at hard threshold amounted to 46.5572 dB. As for the type of threshold is best depends on the input data which is owned, there are 15 from 30 data that indicates the best soft threshold and there are 15 data indicates some best hard threshold.