| 摘要 |
PURPOSE:To obtain the good synthesized voice having a high degree of approximation to a sound source signal at a bit rate of about 4.8kb/s by expressing the sound source signal of one pitch section (key section) by using a small number of pulses to give an amplitude and phase and a code book to indicate the characteristics of the sound source signal. CONSTITUTION:The voice signal of a frame is divided to every pitch section corresponding to the pitch period determined from a pitch parameter. The sound source signal of one pitch section in the pitch sections is then expressed by a small number of the pulses to give the amplitude and phase and the code book 175 to express the characteristics of the sound source signal and the amplitude and phase of the pulse are so determined as to decrease the error between the voice signal and the synthesis signal obtd. by the code book 175. One code word is then selected from the code book 175 and the pitch parameter and spectrum parameter, the amplitude and phase of the pulse, and the index indicating the pitch parameter are outputted. The coding and decoding of the voice signal with high quality by a small computing quantity at the low bit rate, more particularly about 4.8kb/s are possible in his way. |
