| 摘要 |
Provided is an audio decoding device capable of obtaining a preferable synthesized sound with a stable sound volume. The audio decoding device includes: a post filter (210) which performs a process for improving subjective quality of audio and a process for improving subjective quality of a steady-state noise on an output signal of a synthesis filter (209); an amplitude ratio/change amount calculation unit (211) which calculates the amplitude ratio of the input signal and the output signal of the post filter (210) and calculates the fluctuation amount of the amplitude ratio for each of sub-frames; a smoothing coefficient setting unit (212) sets a smoothing coefficient on each of the sub-frames by using the amplitude ratio of the input signal and the output signal of the post filter (210) and the fluctuation amount of the amplitude ratio; an adjustment coefficient setting unit (213) which sets an adjustment coefficient for each sample by using the amplitude ratio of the input signal and the output signal of the post filter (210) and the smoothing coefficient; and a power adjusting unit (214) which multiplies the output signal of the post filter (210) by the adjustment coefficient so as to adjust the power of the output signal of the post filter (210).
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