| 摘要 |
PROBLEM TO BE SOLVED: To improve transmission efficiency and compression efficiency and to realize a natural call. SOLUTION: An LPC analyzer 13 performs linear predictive analysis of a sound signal of a telephone band of a soundless section detected by a sound detector 12, and calculates an occurrence coefficient of a random noise. A selection circuit 16 selects and outputs any one among the analysis result of the LPC analyzer 13 and a digital sound signal delayed by a delay buffer 15 and 'no data' according to the detection result of the sound detector 12 and the detection result of the sound detector 12 delayed by a delay circuit 14. A synthesis filter 26 generates the random noise from a random number signal of a random number generator 25 based on a coefficient from a sound encoding part 1 inputted through a switch 22. A selection circuit 28 selects and outputs any one side between a regenerative sound signal from a sound decoder 24 and the random noise from the synthesis filter 26 according to the detection result of a sound/soundless data detector 21 delayed by the delay circuit 27. |
