QUAD-BAND EXCITATION FOR LOW BIT-RATE SPEECH CODING

The excitation parameters of a multiband excitation model for speech p roduction consist of a pitch period and a series of voiced/unvoiced (v /uv) decisions for a number of fixed frequency bands around the harmon ics of the fundamental. In this paper, it is shown that, at most, four v/uv variable-length nonoverlapping frequency bands spanning over the telephone bandwidth are adequate to represent the excitation spectrum that provides an improved modeling of mixed voicing and noisy speech. A quad-band excitation (QBE) method is presented which generates exci tation source for a linear prediction vocoder for low bit rate transmi ssion of speech signal and the DRT scores validate the potential of th e method. (C) 1996 Acoustical Society of America.