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1. US20120114142 - Acoustic signal processing apparatus, processing method therefor, and program

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Claims

1. An acoustic signal processing apparatus comprising:
a difference spectrum calculation unit that calculates, as a difference spectrum, a difference between frequency spectra of acoustic signals of two channels;
a low-level band determination unit that determines a low-level band in an envelope of the difference spectrum based on a low-level threshold;
a substitution spectrum generation unit that generates a substitution spectrum for which the difference spectrum is substituted, on the basis of at least one of the frequency spectra of the acoustic signals of the two channels;
a spectrum substitution unit that substitutes a difference spectrum corresponding to the low-level band within the difference spectrum calculated by the difference spectrum calculation unit, for the substitution spectrum; and
an accompaniment signal generation unit that generates an accompaniment signal by converting a frequency spectrum output from the spectrum substitution unit into a time-domain signal.
2. The acoustic signal processing apparatus according to claim 1, wherein
the substitution spectrum generation unit generates the substitution spectrum on the basis of at least one frequency spectrum of the acoustic signals of the two channels and a predetermined level adjustment coefficient for adjusting a level of the substitution spectrum.
3. The acoustic signal processing apparatus according to claim 2, wherein
the substitution spectrum generation unit generates the substitution spectrum on the basis of a level adjustment coefficient of an audio band, which is smaller than a level adjustment coefficient corresponding to a band other than the audio band, and the level of the at least one frequency spectrum.
4. The acoustic signal processing apparatus according to claim 1, further comprising
an audio coefficient setting unit that sets an audio coefficient corresponding to an audio band on the basis of a level ratio of, in at least one frequency spectrum of the acoustic signals of the two channels, a frequency spectrum corresponding to a band other than the audio band to a frequency spectrum corresponding to the audio band,
wherein the substitution spectrum generation unit generates the substitution spectrum on the basis of the at least one frequency spectrum and the audio coefficient set by the audio coefficient setting unit.
5. The acoustic signal processing apparatus according to claim 4, wherein
the audio coefficient setting unit sets the audio coefficient to be larger for a higher level of the frequency spectrum corresponding to the band other than the audio band, and sets the audio coefficient to be smaller for a higher level of the frequency spectrum corresponding to the audio band.
6. The acoustic signal processing apparatus according to claim 1, wherein
the low-level band determination unit determines the low-level band using the low-level threshold, which is set on the basis of a level of at least one frequency spectrum of the acoustic signals of the two channels, and a level of the difference spectrum.
7. An accompaniment signal generation method comprising:
calculating, as a difference spectrum, a difference between frequency spectra of acoustic signals of two channels;
determining a low-level band in an envelope of the difference spectrum based on a low-level threshold;
generating a substitution spectrum for which the difference spectrum is substituted, on the basis of at least one of the frequency spectra of the acoustic signals of the two channels;
substituting a difference spectrum corresponding to the low-level band within the difference spectrum, for the substitution spectrum; and
generating an accompaniment signal by converting a frequency spectrum output from the substitution into a time-domain signal.
8. A non-transitory computer readable storage medium having stored thereon, a computer program, the computer program when executed by a computer causes the computer to perform steps comprising:
calculating, as a difference spectrum, a difference between frequency spectra of acoustic signals of two channels;
determining a low-level band in an envelope of the difference spectrum based on a low-level threshold;
generating a substitution spectrum for which the difference spectrum is substituted, on the basis of at least one of the frequency spectra of the acoustic signals of the two channels;
substituting a difference spectrum corresponding to the low-level band within the difference spectrum, for the substitution spectrum; and
generating an accompaniment signal by converting a frequency spectrum output from the substitution into a time-domain signal.