Voice band expansion device, voice band expansion method, and communication apparatus
First Claim
1. A voice band expansion device comprising:
- a time-frequency converter that calculates, using a processor, a frequency spectrum of a voice signal having a first frequency band, by performing time-frequency conversion on the voice signal every frame having a predetermined time length;
a separator that extracts, from the frequency spectrum, an envelope amplitude spectrum of the frequency spectrum, a periodic amplitude spectrum whose spectrum intensity periodically changes in response to frequency, and a random amplitude spectrum whose spectrum intensity randomly changes in response to frequency;
an envelope amplitude spectrum band expander that expands a frequency band of the envelope amplitude spectrum to a second frequency band that is different from the first frequency band;
a periodic amplitude spectrum band expander that expands a frequency band of the periodic amplitude spectrum to the second frequency band;
a random amplitude spectrum band expander that expands a frequency band of the random amplitude spectrum to the second frequency band;
a broadband spectrum calculator that calculates a broadband frequency spectrum having the first frequency band and the second frequency band, by combining the band-expanded envelope amplitude spectrum, the band-expanded periodic amplitude spectrum, and the band-expanded random amplitude spectrum; and
a frequency-time converter that generates a voice signal having the first frequency band and the second frequency band, by performing frequency-time conversion on the broadband frequency spectrum.
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Abstract
A voice band expansion device includes a time-frequency converter that calculates a frequency spectrum of a voice signal having a first frequency band; a separator that extracts, from the frequency spectrum, an envelope amplitude spectrum, a periodic amplitude spectrum, and a random amplitude spectrum; an envelope amplitude spectrum band expander that expands a frequency band to a second frequency band that is different from the first frequency band; a periodic amplitude spectrum band expander that expands a frequency band to the second frequency band; a random amplitude spectrum band expander that expands a frequency band of the random amplitude spectrum to the second frequency band; a broadband spectrum calculator that calculates a broadband frequency spectrum having the first frequency band and the second frequency band; and a frequency-time converter generates a voice signal having the first frequency band and the second frequency band.
11 Citations
18 Claims
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1. A voice band expansion device comprising:
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a time-frequency converter that calculates, using a processor, a frequency spectrum of a voice signal having a first frequency band, by performing time-frequency conversion on the voice signal every frame having a predetermined time length; a separator that extracts, from the frequency spectrum, an envelope amplitude spectrum of the frequency spectrum, a periodic amplitude spectrum whose spectrum intensity periodically changes in response to frequency, and a random amplitude spectrum whose spectrum intensity randomly changes in response to frequency; an envelope amplitude spectrum band expander that expands a frequency band of the envelope amplitude spectrum to a second frequency band that is different from the first frequency band; a periodic amplitude spectrum band expander that expands a frequency band of the periodic amplitude spectrum to the second frequency band; a random amplitude spectrum band expander that expands a frequency band of the random amplitude spectrum to the second frequency band; a broadband spectrum calculator that calculates a broadband frequency spectrum having the first frequency band and the second frequency band, by combining the band-expanded envelope amplitude spectrum, the band-expanded periodic amplitude spectrum, and the band-expanded random amplitude spectrum; and a frequency-time converter that generates a voice signal having the first frequency band and the second frequency band, by performing frequency-time conversion on the broadband frequency spectrum. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A voice band expansion method comprising:
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calculating, using a processor, a frequency spectrum of a voice signal having a first frequency band, by performing time-frequency conversion on the voice signal every frame having a predetermined time length; extracting, from the frequency spectrum, an envelope amplitude spectrum of the frequency spectrum, a periodic amplitude spectrum whose spectrum intensity periodically changes in response to frequency, and a random amplitude spectrum whose spectrum intensity randomly changes in response to frequency; expanding a frequency band of the envelope amplitude spectrum to a second frequency band that is different from the first frequency band; expanding a frequency band of the periodic amplitude spectrum to the second frequency band; calculating a broadband frequency spectrum having the first frequency band and the second frequency band, by combining the band-expanded envelope amplitude spectrum, the band-expanded periodic amplitude spectrum, and the band-expanded random amplitude spectrum; and generating a voice signal having the first frequency band and the second frequency band, by performing frequency-time conversion on the broadband frequency spectrum. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A communication apparatus comprising:
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a communication unit that receives a coded voice signal having a first frequency band; a baseband processor that decodes the voice signal; a controller that expands the first frequency band of the voice signal, the controller comprising; a time-frequency converter that calculate a frequency spectrum of the voice signal having the first frequency band, by performing time-frequency conversion on the voice signal every frame having a predetermined time length; a separator that extracts, from the frequency spectrum, an envelope amplitude spectrum of the frequency spectrum, a periodic amplitude spectrum whose spectrum intensity periodically changes in response to frequency, and a random amplitude spectrum whose spectrum intensity randomly changes in response to frequency; an envelope amplitude spectrum band expander that expands a frequency band of the envelope amplitude spectrum to a second frequency band that is different from the first frequency band; a periodic amplitude spectrum band expander that expands a frequency band of the periodic amplitude spectrum to the second frequency band; a random amplitude spectrum band expander that expands a frequency band of the random amplitude spectrum to the second frequency band; a broadband spectrum calculator that calculates a broadband frequency spectrum having the first frequency band and the second frequency band, by combining the band-expanded envelope amplitude spectrum, the band-expanded periodic amplitude spectrum, and the band-expanded random amplitude spectrum; and a frequency-time converter that generates a voice signal having the first frequency band and the second frequency band, by performing frequency-time conversion on the broadband frequency spectrum; and a loudspeaker that reproduces the band-expanded voice signal. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification