Music – Instruments – Electrical musical tone generation
Reexamination Certificate
2002-03-18
2004-03-09
Donels, Jeffrey (Department: 2837)
Music
Instruments
Electrical musical tone generation
C434S30700R
Reexamination Certificate
active
06703551
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a musical scale recognition method and an apparatus thereof, and more specifically, to a musical scale recognition method and an apparatus thereof for comparing an input audio signal with a predetermined musical note.
2. Description of the Prior Art
Such a kind of a conventional musical scale recognition apparatus made measurements of a frequency component employing a Fast Fourier Transformation (FFT) in regard to an input audio signal, and carried out a musical scale recognition on the basis of the measurement result thereof.
However, there needed to be a microprocessor or a DSP (digital signal processor) with a high processing capability in order to analyze all frequency components included in the audio signal in real time because the Fourier transformation had to be done at high speed.
SUMMARY OF THE INVENTION
Therefore, a primary object of the present invention is to provide a musical scale recognition method and an apparatus thereof that even a microprocessor with a low processing capability can perform a musical scale recognition in real time.
A first musical scale recognition method according to the present invention, comprises following steps of (a) converting an input analog audio signal into digital data D by sampling the audio signal at constant intervals C; (b) deriving sin &ohgr;t and cos &ohgr;t (&ohgr; is an angular velocity in correspondence to an observed frequency f) based upon the observed frequency f and a time t; (c) calculating a cumulative value As to find a coefficient of a Fourier sine series by performing an operation of an equation (1); (d) calculating a cumulative value Ac to find a coefficient of a Fourier cosine series by performing an operation of an equation (2); (e) calculating a frequency power spectrum effective value A by performing an operation of an equation (3); (f) evaluating a component of the frequency f included in an analog audio signal on the basis of the numeric value A; and (g) renewing the time t by performing an operation of an equation (4).
As←As+D·sin &ohgr;t (1)
Ac←Ac+D·cos &ohgr;t (2)
A←{square root over (As
2
+Ac
2
)} (3)
t←t+C (4)
A second musical recognition method according to the present invention, comprises following steps of (a) converting an input analog audio signal into digital data D by sampling the audio signal at constant intervals C; (b) deriving sin &ohgr;t and cos &ohgr;t (&ohgr; is an angular velocity in correspondence to an observed frequency f) based upon the observed frequency f and a time t; (c) a calculating a cumulative value As to find a coefficient of a Fourier sine series by performing an operation of the above equation (1); (d) calculating a cumulative value Ac to find a coefficient of a Fourier cosine series by performing an operation of the above equation (2); (e) calculating a frequency power spectrum effective value A by performing an operation of a below equation (5); (f) evaluating a component of the frequency f included in the analog audio signal on the basis of the numeric value A; and (g) renewing the time t by performing an operation of the above equation (4).
A←As
2
+Ac
2
(5)
A first musical recognition apparatus according to the present invention, comprises an analog/digital converting means which converts an input analog audio signal into a digital data D by sampling the audio signal at constant intervals C; a deriving means which derives sin &ohgr;t and cos &ohgr;t (&ohgr; is an angular velocity in correspondence to an observed frequency f) based upon the observed frequency f and a time t; a first operating means which calculates a cumulative value As to find a coefficient of a Fourier sine series by performing an operation of an equation (1); a second operating means which calculates a cumulative value Ac to find a coefficient of a Fourier cosine series by performing an operation of an equation (2); a third operating means which calculates a frequency power spectrum effective value A by performing an operation of an equation (3); an evaluating means which evaluates a component of the frequency f included in the analog audio signal on the basis of the numeric value A; and a renewing means which renews the time t by performing an operation of above equation (4).
A second musical recognition apparatus according to the present invention, comprises an analog/digital converting means which converts an input analog audio signal into a digital data D by sampling the audio signal at constant intervals C; a deriving means which derives sin &ohgr;t and cos &ohgr;t (&ohgr; is an angular velocity in correspondence to an observed frequency f) based upon the observed frequency f and a time t; a first operating means which calculates a cumulative value As to find a coefficient of a Fourier sine series by performing an operation of the above equation (1); a second operating means which calculates a cumulative value Ac to find a coefficient of a Fourier cosine series by performing an operation of the above equation (2); a third operating means which calculates a frequency power spectrum effective value A by performing an operation of the above equation (5); an evaluating means which evaluates a component of the frequency f included in the analog audio signal on the basis of the numeric value A; and a renewing means which renews the time t by performing an operation of the above equation (4).
A third musical scale recognition apparatus according to the present invention, comprises a BGM reproducing means which reproduces a karaoke BGM on the basis of musical score data; musical score data storing means which stores musical score data and musical scale data having an exemplary melody for singing included in synchronous with the musical score data; a reading means which reads the musical scale data from the musical score data storing means at a time t; a setting means which sets a frequency of the musical scale data read by the reading means to an observed frequency f; a musical scale recognition means which performs a musical scale recognition by using any one of the above musical scale recognition methods; and an outputting means which outputs an evaluation result by the evaluating means.
A fourth musical scale recognition apparatus according to the present invention, comprises, a BGM reproducing means which reproduces a karaoke BGM on the basis of musical score data; a musical score data storing means which stores musical score data and musical scale data having an exemplary melody for singing included in synchronous with the musical score data; a reading means which reads musical scale data from the musical score data storing means at a time t; a setting means which sets a frequency of the musical scale data read by the reading means to an observed frequency f
0
, a frequency of a musical scale one octave below the musical scale data read by the reading means to an observed frequency f
1
, and a frequency of a musical scale one octave above the musical scale data read by the reading means to an observed frequency f
2
; a musical scale recognition means which carries out a musical scale recognition by using the above described musical scale recognition methods; and an outputting means which outputs an evaluation result by the evaluation means.
A fifth musical scale recognition apparatus according to the present invention, comprises a musical scale recognition means which sequentially carries out a musical scale recognition of an analog audio signal by using any one of the above musical scale recognition methods; a comparing means which compares a changing pattern of the musical scale recognized by the musical scale recognition means with a predetermined musical phrase; and a first operating means which performs a predetermined operation brought into correspondence with this relevant musical phrase when the changing pattern of the musical scale recognized by the musical scale recognition means becomes coin
Kato Shuhei
Ueshima Hiromu
Arent Fox Kintner & Plotkin & Kahn, PLLC
Donels Jeffrey
SSD Company Limited
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