Wideband speech coding algorithm with application of discrete wavelet transform to upper band

In this paper, we propose a new wideband speech coder which combines the European standard of a narrowband speech coder, i.e., GSM-EFR, and a transform coder using the discrete wavelet transform. Input speech is first split into two bands with equal bandwidth. A subband coder with wavelet transformed speech is designed for a upper band coder, and a GSM-EFR coder is adopted as a lower band coder. The total bit rate of the proposed coder is 18.9 kbps, and informal listening test results have shown that the proposed coder has comparable speech quality to that of G.722 with 56 kbps.