US 2002/0170414 A1 · Musical scale recognition method and apparatus thereof

Abstract

A musical scale recognition apparatus includes an analog/digital converter and a processor, and can determine by the processor how close an input analog audio signal is to a musical scale of a musical tone to be recognized by repeatedly performing a calculation of a cumulative value As to find a coefficient of a Fourier sine series of the audio signal on the basis of a frequency f and digital data D, a cumulative value Ac to find a coefficient of a Fourier cosine series of the audio signal on the basis of the frequency f and the digital data D, and a frequency power spectrum effective value A of the audio signal on the basis of the cumulative value As and the cumulative value Ac, wherein the digital data into which the input analog audio signal is converted by the analog/digital converter is D, the frequency (musical scale) of the musical tone to be recognized is f, and a current time is t. At this time, A is a value which shows how close the input audio signal is to the musical sound to be recognized, and it is shown that the larger the value A becomes, the closer the both sides are.

Claims26

Dependent claims

A musical scale recognition method, comprising following steps of:

(a) sampling an input analog audio signal at a constant time interval C and converting into digital data D;
(b) deriving sin ωt and cos ωt (6) is an angular velocity corresponding to an observed frequency f) based upon the observed frequency f and a time t;
(c) making an operation of an equation (1) and calculating a cumulative value As to find a coefficient of Fourier sine series;
As←As+D·sin ωt (1)
(d) making an operation of an equation (2) and calculating a cumulative value Ac to find a coefficient of Fourier cosine series;
Ac←Ac+D·cos ωt (2)
(e) making an operation of an equation (3) and calculating a frequency power spectrum effective value;
A←{square root}{square root over (As2+Ac2)} (3)
(f) evaluating a component of said frequency f included in said analog audio signal on the basis of said numeric value A;
and
(g) making an operation of an equation (4) and renewing said time t.
t←t+C (4)

9 more elements

A musical scale recognition apparatus, comprising:

an analog/digital converting means which applies a sampling to the input analog audio signal at a constant time interval C and converts into digital data;
a deriving means which derives sin ωt and cos ωt (ω is an angular velocity corresponding to an observed frequency f) based upon the observed frequency f and a lime t;
a first calculating means which makes an operation of an equation (1) and calculating a cumulative value As to find a coefficient of Fourier sine series;
As←As+D·sin ωt (1)
a second calculating means which makes an operation of an equation (2) and calculating a cumulative value Ac to find a coefficient of Fourier cosine series;
Ac←Ac+D·cos ωt (2)
a third calculating means which makes an operation of an equation (3) and calculating a frequency power spectrum effective value;
A←{square root}{square root over (As2+Ac2)} (3)
an evaluating means which evaluates a component of said frequency f included in said analog audio signal on the basis of said numeric value A;
and
a renewing means which makes an operation of an equation (4) and renewing said time t.
t←t+C (4)

9 more elements

A musical scale recognition apparatus, comprising:

an analog/digital converting means which applies a sampling to the input analog audio signal at a constant time interval C and converts into digital data;
a deriving means which derives sin ωt and cos ωt (ω is an angular velocity corresponding to an observed frequency f) based upon the observed frequency f and a time t;
a first calculating means which makes an operation of an equation (1) and calculating a cumulative value As to find a coefficient of Fourier sine series;
As←As+D·sin ωt (1)
a second calculating means which makes an operation of an equation (2) and calculating a cumulative value Ac to find a coefficient of Fourier cosine series;
Ac←Ac+D·cos ωt (2)
a third calculating means which makes an operation of an equation (5) and calculating a frequency power spectrum effective value;
A←As2+Ac2 (5)
an evaluating means which evaluates a component of said frequency f included in said analog audio signal on the basis of said numeric value A;
and
a renewing means which makes an operation of an equation (4) and renewing said time t.
t←t+C (4)

9 more elements

Dependencies are inferred from the claim text.

Musical scale recognition method and apparatus thereof

Life of this patent

Musical scale recognition method and apparatus thereof

Life of this patent

Abstract

Claims26