| 摘要 |
PROBLEM TO BE SOLVED: To provide an interoperable vocoder which has the tone quality improved and has the fidelity to tone signals improved and has the robustness against background noise improved. SOLUTION: When a digital speech sample sequence is encoded into a bit stream, digital speech samples are divided into one or more frames, and a set of model parameters are computed for the frames (205). The set of model parameters includes at least a first parameter conveying pitch information. The voicing state of a frame is determined, and the first parameter conveying pitch information is modified to designate the determined voicing state of the frame in the case that the determined voicing state of the frame is equal to one of a set of reserved voicing states. The model parameters are quantized to generate quantizer bits (210), which are used to produce the bit stream (215). COPYRIGHT: (C)2005,JPO&NCIPI
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