DEVICE AND METHOD FOR CODING EXCITING SIGNAL OF VOICE

摘要

PURPOSE:To execute voice coding even to the voice having a short pitch period to make it high quality sound. CONSTITUTION:LPC coefficients of inputted voice signal are calculated by an LPC analyzing circuit 20 and weighted voice vectors are calculated by a weighting circuit 30 using a weighting filter W(z) in an equation III. An exciting vector y is calculated by a pitch period processing circuit 85 from the adaptive source code vectors outputted from an adaptive code book circuit 40 and the sound code vectors outputted from a sound source code book circuit 80 using an equation I. The vector y is inputted to a weighting synthesis circuit 90 and a weighting synthesis vector WHy is calculated using a weighted synthesis filter W(z)H(z) expressed by equations II and III which are constituted by using the LPC coefficients. Then, an evaluating circuit 95 calculates a mean square error D of Ws and WHy with respect to a delay L within a beforehand set range and each sound source code vector stored in the circuit 80, the delay L and the index of the sound source code vector for which D becomes a minimum are decided and are respectively outputted from index output terminals 96 and 97.