| 摘要 |
A speech signal coding apparatus includes a dividing section for dividing a speech signal in units of sub-frames. A spectrum parameter section calculates a spectrum parameter for each sub-frame. An error signal generating section generates a perceptual sensitivity weighted error signal from a reproduction signal and the speech signal for a sub-frame. An adaptive code book is referred to based on the perceptual sensitivity weighted error signal so that an adaptive code vector and a pitch period is selected. Also, an excitation code book is referred to based on the perceptual sensitivity weighted error signal so that an excitation code vector from the excitation code book is selected. In a gain code vector section having a gain code book which stores gain code vectors, a gain code book is referred to based on the perceptual sensitivity weighted error signal, so that a gain code vector is selected. Gains are determined from the selected gain code vector in units of time intervals shorter than the sub-frame, and the reproduction signal is generated by weighting the adaptive code vector and excitation code vector with the determined gains in units of time intervals.
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