An Improved Psychoacoustic Model for Audio Coding Based on Wavelet Packet

This paper describes a new design of a psychoacoustic model for audio coding following the model used in the standard MPEG-1 audio layer 3 using an appropriate wavelet packet decomposition of the speech/audio signal. The design of a psychoacoustic model is achieved by wavelet packet decomposition whose connections are selected in such a way that sub bands correspond to the best possible one to the critical bands. For that, we used gammachirp wavelet packet because gammachirp filter underwent a good success in psychoacoustic research. In order to investigate this new design of a psychoacoustic model based on wavelet packet decomposition, we proceed to some experimental results: the distribution curve of masking threshold for tone at 1 kHz and for a real complex signal were calculated by utilizing the two different psychoacoustic models respectively, the old one based on FFT analysis and the newest one based on wavelet packet analysis especially gammachirp wavelet packet. Also, we show some gammachirp scalograms of some audio sounds.