A simple and efficient two-band speech coder at 2.4 kbit/s for real-time implementation on a single low-cost DSP

In the new generation of very low bit rate speech coding models, multiband excitation (MBE) represents one of the most promising techniques. The paper proposes a new low-complexity two-band coding scheme capable of producing good speech quality at 2.4 kbit/s. Two new solutions are proposed to guarantee pitch continuity and establish the frequency of transition between the voiced and unvoiced portions of band. During informal listening tests we have seen that the speech coder proposed maintains a natural quality, perfect intelligibility and speaker identity. Finally, to demonstrate the simplicity of the algorithms proposed, the paper presents an evaluation of the speech coder complexity for a real-time implementation on a single low-cost digital signal processor.