| 摘要 |
There is provided a first adder which synthesizes input audio signals in a plurality of channels, a first band-pass filter which transmits only a signal in a predetermined frequency band in the audio signals synthesized by the first adder, and a full-wave rectification circuit which generates an even-order harmonic signal of the audio signal transmitted from the first band-pass filter. A lower limit frequency of the first band-pass filter is set at a value such that a frequency interval between adjacent orders of the even-order harmonic signal generated by the full-wave rectification circuit is not less than a critical bandwidth of a signal frequency band from a reproduction lower limit frequency of a speaker to be used to an upper limit frequency of a harmonic wave to be used to boost the bass.
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