Perceptual speech coding using time and frequency masking constraints

This paper presents a new wide-band speech coding system based on a fast wavelet packet transform algorithm as well as a formulation of temporal and spectral psychoacoustic models of masking. The proposed FFT-like overlapped block orthogonal transform allows us to approximate the auditory critical band decomposition in an efficient manner, which is a major advantage over previous approaches that used uniform filter banks. As a result of such a decomposition, the perceptually tuned time-frequency structure of the original speech signal is preserved. This allows us to make use of the temporal and spectral properties of the human auditory system to decrease the average bit rate of the encoder, while perceptually hiding the quantization error