JP2008015380A - Sound reproducing apparatus, high frequency adding device, sound reproduction method and high frequency addition method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a signal having a required high frequency component without depending on a sound source in reproducing a sound source signal by adding a high frequency component to the sound source signal from which the high frequency component is reduced beforehand. <P>SOLUTION: An oversampling part 210 generates a first signal s(t) by oversampling a sound signal from which a high frequency component more than a prescribed frequency is removed beforehand. A high frequency component generation part 220 generates a second signal X(t) having a high frequency component with a fixed frequency f on the basis of a numerical expression (1) in which a term of the sound signal or the first signal s(t) is not included. By multiplying the first signal s(t) generated by the oversampling part 210 by the second signal X(t) generated by the high frequency component generation part 220, a third signal Y(t) to which the high frequency component with the required frequency is added to the sound signal is generated without depending on a sound source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sound reproducing device, a high frequency applying device, a sound reproducing method, and a high frequency adding method.

  It is known that a sound with a high frequency that is higher than the audible frequency is not consciously perceived by humans (see Non-Patent Document 1). For this reason, conventionally, for example, a high frequency sound of 22 kHz or higher has been cut in advance in a sound source such as a CD. On the other hand, it may be necessary to add a desired high frequency component to a sound source from which the high frequency component has already been removed, for example, in order to improve the reproduction sound quality.

Patent Documents 1 and 2 describe techniques for generating a signal having a high-frequency component. In the technique described in Patent Document 1, a high frequency component is generated by estimation based on a harmonic sequence of a fundamental frequency component of a sound source signal. In the technique described in Patent Document 2, a signal having a high frequency component is generated by oversampling the sound source signal and further rectifying the half wave or both waves.
Muraoka T, Yamada Y, Yamazaki M, Sampling-frequency considerations in digital audio, J Audio Engineer Soc 26, 252-256, 1978. JP 2003-108197 A JP 2003-15695 A

  As described in Patent Document 1 and Patent Document 2, in the conventional technology, when a signal having a high-frequency component is generated, a sound source signal is used as a source. For this reason, the high frequency component contained in the generated signal often depends on the original sound source signal. Therefore, in the case of the prior art, when trying to add the high frequency component to the sound source signal from which the high frequency component has been removed in advance, the high frequency component depending on the ratio of the frequency component of the sound source signal can be obtained. For example, it has been difficult to obtain a desired high frequency component unrelated to the ratio of the frequency component of the sound source signal.

  Therefore, the present invention has been made in view of the above, and an acoustic reproduction device capable of obtaining a signal having a desired high-frequency component when adding the high-frequency component to a sound source signal from which the high-frequency component has been removed in advance, An object of the present invention is to provide a high frequency applying device, a sound reproducing method, and a high frequency applying method.

  In order to solve the above-described problem, the sound reproducing apparatus of the present invention includes a first sound source signal input from a sound source signal from which a high frequency component equal to or higher than a predetermined frequency has been removed, and oversampling the sound source signal. Separately from the oversampling means for generating the signal, the sound source signal or the first signal, the high frequency component generating means for generating a second signal having a high frequency component of a constant frequency, the first signal and the second signal Multiplying means for generating a third signal in which a high-frequency component of a certain frequency is added to the sound source signal by multiplying the signal, and converting the electric signal in the third signal into an acoustic signal, And a reproducing means for reproducing both the second signal and the second signal.

  Further, in the sound reproduction method of the present invention, the input means inputs the sound source signal from which the high frequency component equal to or higher than the predetermined frequency has been removed in advance, and the oversampling means oversamples the sound source signal, An oversampling step for generating a first signal, and a high-frequency component generating step for generating a second signal having a high-frequency component having a constant frequency by the high-frequency component generating means separately from the sound source signal or the first signal; The multiplication means generates a third signal in which a high frequency component of a constant frequency is added to the sound source signal by multiplying the first signal and the second signal, and the reproduction means And a reproduction step of reproducing both the sound source signal and the second signal by converting the electrical signal in the signal No. 3 into an acoustic signal.

  According to such a sound reproducing device and sound reproducing method of the present invention, the high frequency component generating means generates the second signal having a high frequency component of a constant frequency separately from the sound source signal or the first signal. . Then, the generated second signal and the first signal are multiplied to generate a third signal in which a high-frequency component having a constant frequency is added to the sound source signal. By converting the third signal into an acoustic signal, the sound source signal and the second signal are reproduced as sound.

  Thus, the second signal generated by the high frequency component generating means is independent of the sound source signal or the first signal obtained by oversampling the sound source signal in terms of the frequency component. That is, the high frequency component generating means can generate a second signal including a high frequency component of a desired frequency without depending on the sound source. Further, the multiplying unit can generate a third signal in which a high frequency component of a desired frequency is added to the sound source signal by multiplying the second signal and the first signal. The sound reproduced by the reproducing means includes a high-frequency component having a desired frequency that does not depend on the sound source signal, along with the sound source signal.

The high frequency adding apparatus of the present invention includes an oversampling unit that generates a first signal by oversampling a sound source signal from which a high frequency component of a predetermined frequency or higher has been removed in advance, and a sound source signal or a first signal. Separately from the above, the high frequency component generating means for generating the second signal having the high frequency component of the constant frequency and the first signal and the second signal are multiplied to thereby generate the high frequency component of the constant frequency as the sound source. Multiplying means for generating a third signal added to the signal, and the oversampling means generates the first signal by oversampling the sound source signal at a frequency equal to or higher than twice the fixed frequency, The high frequency component generating means is represented by the following formula (1).
X (t) = a {1 + sin (2πft−θ)} (1)
(Wherein, a represents an arbitrary coefficient, f represents a constant frequency, t represents time, and θ represents a phase at the frequency f.)
Thus, a second signal X (t) having a high frequency component of a constant frequency f is generated.

The high frequency addition method of the present invention includes an oversampling step in which the oversampling means generates a first signal by oversampling a sound source signal from which a high frequency component of a predetermined frequency or higher has been removed in advance, and a high frequency component A generating means generates a second signal having a high frequency component of a constant frequency separately from the sound source signal or the first signal, and a multiplying means generates the first signal and the second signal. And a multiplication step for generating a third signal in which a high-frequency component having a constant frequency is added to the sound source signal. In the oversampling step, the sound source has a frequency that is at least twice the constant frequency. The first signal is generated by oversampling the signal. In the high frequency component generation step, the following formula (1)
X (t) = a {1 + sin (2πft−θ)} (1)
(Wherein, a represents an arbitrary coefficient, f represents a constant frequency, t represents time, and θ represents a phase at the frequency f.)
Thus, a second signal X (t) having a high frequency component of a constant frequency f is generated.

  According to such a high frequency addition apparatus and high frequency addition method of the present invention, the high frequency component generating means has a high frequency component of a constant frequency f according to Equation (1) separately from the sound source signal or the first signal. A second signal X (t) is generated. Then, the generated second signal X (t) is multiplied by the first signal, thereby generating a third signal in which a high frequency component of a constant frequency f is added to the sound source signal.

  As shown in Equation (1), the second signal X (t) generated by the high frequency component generating means is a ratio of the frequency component to the sound source signal or the first signal obtained by oversampling the sound source signal. Is irrelevant. That is, the term relating to the sound source signal or the first signal does not exist in Equation (1). For this reason, the high frequency component generating means can generate the second signal X (t) including the high frequency component of the desired frequency f without depending on the sound source based on the formula (1). Further, the multiplication means may generate a third signal in which a high frequency component of a desired frequency f is added to the sound source signal by multiplying the second signal X (t) and the first signal. it can.

Further, the multiplication means of the high frequency adding device is expressed by the following formula (2).
Y (t) = a {1 + sin (2πft−θ)} s (t) (2)
(Where s (t) represents the first signal)
By multiplying the first signal s (t) by the second signal X (t), the third signal Y (t) in which the high frequency component of the constant frequency f is added to the sound source signal is generated. To do.

In the multiplication step of the high frequency addition method, the following mathematical formula (2)
Y (t) = a {1 + sin (2πft−θ)} s (t) (2)
(Where s (t) represents the first signal)
By multiplying the first signal s (t) by the second signal X (t), the third signal Y (t) in which the high frequency component of the constant frequency f is added to the sound source signal is generated. To do.

  In these inventions, for any one second signal X (t) generated by the high frequency component generating means, the multiplying means converts the third signal Y (t) based on the equation (2). This is particularly useful when generating. The multiplication means multiplies the second signal X (t) and the first signal s (t) by Equation (2) to add a high frequency component of one desired frequency f to the sound source signal. A third signal Y (t) can be generated.

（式中、ｎは複数発生された第２の信号の個数であり、ｉはｎ個の第２の信号のうち何れか一つに対する識別子であってｎ以下の自然数であり、ａ_ｉはｉ番目の第２の信号における任意の係数を表し、ｆ_ｉはｉ番目の第２の信号における周波数を表し、θ_ｉは該周波数ｆ_ｉにおける位相を表す。）
により、第１の信号ｓ（ｔ）と複数の第２の信号の総和とを乗算することにより、複数の高周波成分が音源信号に付加された第３の信号Ｙ（ｔ）を生成する。 Further, the high frequency component generating means of the high frequency adding device generates a plurality of second signals X (t) having high frequency components according to the mathematical expression (1), and the multiplying means is represented by the following mathematical expression (3).

(Where n is the number of the generated second signals, i is an identifier for any one of the n second signals, and is a natural number equal to or less than n, and a _i is i Represents an arbitrary coefficient in the i-th second signal, f _i represents the frequency in the i-th second signal, and θ _i represents the phase at the frequency f _i .)
Thus, by multiplying the first signal s (t) by the sum of the plurality of second signals, a third signal Y (t) in which a plurality of high frequency components are added to the sound source signal is generated.

（式中、ｎは複数発生された第２の信号の個数であり、ｉはｎ個の第２の信号のうち何れか一つに対する識別子であってｎ以下の自然数であり、ａ_ｉはｉ番目の第２の信号における任意の係数を表し、ｆ_ｉはｉ番目の第２の信号における周波数を表し、θ_ｉは該周波数ｆ_ｉにおける位相を表す。）
により、第１の信号ｓ（ｔ）と複数の第２の信号の総和とを乗算することにより、複数の高周波成分が音源信号に付加された第３の信号Ｙ（ｔ）を生成する。 Further, in the high frequency component generating step of the high frequency adding method, a plurality of second signals X (t) having high frequency components are generated by Equation (1), and in the multiplying step, Equation (3) below.

(Where n is the number of the generated second signals, i is an identifier for any one of the n second signals, and is a natural number equal to or less than n, and a _i is i Represents an arbitrary coefficient in the i-th second signal, f _i represents the frequency in the i-th second signal, and θ _i represents the phase at the frequency f _i .)
Thus, by multiplying the first signal s (t) by the sum of the plurality of second signals, a third signal Y (t) in which a plurality of high frequency components are added to the sound source signal is generated.

According to these aspects of the invention, the high-frequency component generating means, based on the equation (1), a plurality generate a second signal having a high frequency component of the frequency f _i. Then, based on Equation (3), the sum of the plurality of second signals generated is multiplied by the first signal s (t) generated by the oversampling means, so that a plurality of frequencies are obtained. A third signal Y (t) in which the high-frequency component of (f ₁ ... F _n ) is added to the sound source signal is generated.

As shown in Equation (1) and Equation (3), each of the plurality of second signals and the sum thereof are the sound source signal or the first signal s (t) obtained by oversampling the sound source signal. Is irrelevant in the proportion of frequency components. That is, the term relating to the sound source signal or the first signal does not exist in Equation (1). Similarly, there is no term relating to the sound source signal or the first signal s (t) in the part representing the sum of the plurality of second signals in Equation (3). Therefore, the high-frequency component generating means, based on the equation (1), without depending on the sound source signal also can be generated by a plurality of second signal including a high frequency component of the desired frequency f _i. Further, the multiplying unit multiplies the sum of the plurality of second signals and the first signal s (t) based on the formula (3), thereby obtaining a plurality of frequencies (f ₁ ... F _n ). A third signal Y (t) in which the high frequency component is added to the sound source signal can be generated.

  According to the present invention, when a high-frequency component is added to a sound source signal from which the high-frequency component has been removed in advance for reproduction, a signal having a desired high-frequency component can be obtained without depending on the sound source. It can be played in any form.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a high-frequency addition device according to the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

[First embodiment]
First, the configuration of the sound reproducing device 1 according to the first embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of the sound reproducing device 1. As shown in FIG. 1, the sound reproducing device 1 includes an input unit 10 (input unit), a high frequency adding unit 20 (high frequency adding device), and a reproducing unit 30 (reproducing unit). In the sound reproducing apparatus 1, the high frequency adding unit 20 adds a high frequency component of a desired frequency (a frequency f described later) to the sound signal input from the input unit 10, and the reproducing unit 30 adds the high frequency component. The reproduced sound signal is reproduced as sound.

  FIG. 2 is a hardware configuration diagram of the sound reproducing device 1. As shown in FIG. 2, the sound reproducing device 1 according to the first embodiment physically includes a CPU 41, a ROM 42 and a RAM 43, which are main storage devices, an operation unit 44 such as an operation button, such as an LCD (Liquid Crystal Display). ) Or the like, an output device 46 such as a speaker, a communication interface 47 for receiving data input from an external device, an auxiliary storage device 48 such as a memory device, and the like. Each function of the sound reproducing device 1 to be described later is configured such that predetermined software is read on hardware such as the CPU 41 and the RAM 43 shown in FIG. 2 to control the operation unit 44, the display 45, and the communication interface 47 under the control of the CPU 41. This is realized by reading and writing data in the RAM 43 and the auxiliary storage device 48. The communication interface 47 can receive a sound source signal from a CD or the like as an external sound source, for example, and the output device 46 can convert an electrical signal into an acoustic signal.

  Returning to FIG. 1, the functional configuration of the sound reproducing device 1 will be described. The input unit 10 inputs a sound source signal to the high frequency adding unit 20. The input unit 10 inputs, for example, a sound source signal received from the external sound source by the communication interface 47 to the high frequency adding unit 20. In the first embodiment, as the sound source signal, for example, audio data recorded on a generally popular CD or the like is assumed. In this sound source signal, a high frequency component of a predetermined frequency or higher such as 25 kHz is removed in advance. FIG. 3 is a diagram for explaining the function of each component of the sound reproducing device 1, and FIG. 3A is a diagram illustrating the sound source signal input to the high frequency adding unit 20 by the input unit 10. As shown in FIG. 3A, the input unit 10 inputs a sound source signal whose amplitude changes with time t to the high frequency adding unit 20.

  Returning to FIG. 1, the high frequency adding unit 20 adds a high frequency component of a desired frequency to the sound source signal input from the input unit 10. As shown in FIG. 1, the high frequency adding unit 20 in the first embodiment includes an oversampling unit 210 (oversampling unit), a high frequency component generation unit 220 (high frequency component generation unit), a multiplication unit 230 (multiplication unit), and a D / A conversion unit 240 is provided. Hereinafter, each component of the high frequency addition part 20 is demonstrated in detail.

  The oversampling unit 210 generates a first signal by oversampling the sound source signal input from the input unit 10. Since the sound source signal input from the input unit 10 is audio data recorded on a CD or the like that is generally spread, it is impossible to add a high frequency higher than the audible frequency to the sound source signal. This is because generally popular audio data is sampled at a frequency lower than 50 kHz. In this state, it is impossible to add a high frequency of 25 kHz or more by a well-known sampling theorem. Therefore, the oversampling unit 210 oversamples the sound source signal at a frequency that is at least twice the frequency of the high frequency component to be added to the sound source signal later. As a result, the oversampling unit 210 can generate a first signal that can receive the addition of the high-frequency component. The oversampling unit 210 outputs the generated first signal to the multiplication unit 230.

The high frequency component generation unit 220 generates a second signal having a high frequency component of a constant frequency separately from the sound source signal or the first signal. The high frequency component generator 220 is expressed by the following mathematical formula (1).
X (t) = a {1 + sin (2πft−θ)} (1)
Thus, a second signal X (t) having a high frequency component of a constant frequency f is generated. In Formula (1), a represents an arbitrary coefficient. f represents a frequency in a high frequency component added to the sound source signal by the multiplier 230 later. t represents time. θ represents the phase at the frequency f.

  FIG. 3B is an image of the second signal X (t) generated by the high frequency component generator 220. As shown in FIG. 3B, the high frequency component generator 220 generates a second signal X (t) whose amplitude changes with time t and has a high frequency component of frequency f. As can be seen from the fact that there is no term relating to the sound source signal or the first signal in Equation (1), the second signal X (t) generated by the high frequency component generator 220 is the sound source signal or the first signal. It is irrelevant in the ratio of frequency components. For this reason, the second signal X (t) can include a high-frequency component having a desired frequency f without depending on the sound source. The high frequency component generator 220 outputs the generated second signal X (t) to the multiplier 230.

The multiplier 230 multiplies the first signal input from the oversampling unit 210 and the second signal X (t) input from the high-frequency component generator 220, thereby generating a high-frequency component having a constant frequency. The added third signal is generated. The multiplication unit 230 has the following mathematical formula (2).
Y (t) = a {1 + sin (2πft−θ)} s (t) (2)
Thus, the third signal Y (t) to which the high frequency component of the frequency f is added is generated. In Equation (2), s (t) represents the first signal.

  FIG. 3C is an image of a third signal Y (t) generated by the multiplication unit 230 multiplying the first signal s (t) and the second signal X (t). As shown in FIG. 3C, the multiplication unit 230 generates a third signal Y (t) to which the amplitude varies depending on the magnitude of the sound source signal and the time t and to which the high frequency component of the frequency f is added. The multiplier 230 outputs the generated third signal Y (t) to the D / A converter 240.

  The D / A converter 240 converts the third signal Y (t) that is input from the multiplier 230 and is a digital signal into an analog signal. The D / A conversion unit 240 outputs the converted analog signal to the reproduction unit 30.

  The reproduction unit 30 reproduces the analog signal input from the D / A conversion unit 240 as sound. The reproduction unit 30 includes, for example, an amplification unit and an electroacoustic conversion unit (not shown), and thereby amplifies the analog signal input from the D / A conversion unit 240 and converts the amplified electric signal into an acoustic signal. Convert. Then, for example, the acoustic signal is reproduced as sound through the output device 46 shown in FIG. The sound reproduced by the reproduction unit 30 includes a high-frequency component having a frequency f along with the sound source signal.

  Next, operations (sound reproduction method and high frequency addition method) performed by the sound reproduction device 1 will be described with reference to FIG. FIG. 4 is a flowchart showing the operation of the sound reproducing device 1.

  First, the input unit 10 inputs, for example, a sound source signal such as audio data recorded on a widely used CD or the like to the high frequency adding unit 20. 3A described above is an image of the sound source signal input to the high frequency adding unit 20 by the input unit 10 (step S101).

  Next, the oversampling unit 210 generates a first signal s (t) by oversampling the sound source signal input from the input unit 10. For example, when a frequency component of the frequency f is added to the sound source signal later, the oversampling unit 210 oversamples the sound source signal at a frequency of at least the frequency 2f. The first signal s (t) generated by the oversampling unit 210 is output to the multiplication unit 230 (step S102).

  Next, the high-frequency component generator 220 has a high-frequency component having a frequency f based on the above-described equation (1) separately from the sound source signal in step S101 or the first signal s (t) in step S102. 2 signal X (t) is generated. FIG. 3B described above imagines the second signal X (t) generated by the high-frequency component generation unit 220. The second signal X (t) generated by the high frequency component generation unit 220 is independent of the sound source signal or the first signal s (t) in terms of the frequency component ratio. That is, the second signal X (t) can include a high-frequency component having a desired frequency f without depending on the sound source. The second signal X (t) generated by the high frequency component generator 220 is output to the multiplier 230 (step S103).

  Next, the multiplication unit 230 generates the third signal Y (t) to which the high frequency component of the frequency f is added based on the above-described equation (2). Multiplier 230 uses first signal s (t) input from oversampling unit 210 in step S102 and second signal X (t) input from high frequency component generator 220 in step S103. By multiplying, the amplitude changes according to the magnitude of the sound source signal and time t, and a third signal Y (t) to which a high frequency component of frequency f is added is generated. FIG. 3C described above imagines the third signal Y (t) generated by the multiplication unit 230. The third signal Y (t) generated by the multiplier 230 is output to the D / A converter 240 (step S104).

  Next, the D / A converter 240 converts the third signal Y (t) input from the multiplier 230 in step S104 into an analog signal. Then, the converted analog signal is converted into an acoustic signal and reproduced as sound (step S105).

  Then, the effect | action and effect of the sound reproduction apparatus 1 concerning 1st Embodiment are demonstrated. According to the sound reproducing device 1 of the first embodiment, the high frequency component generation unit 220 generates a high frequency component having a constant frequency f according to Equation (1) separately from the sound source signal or the first signal s (t). A second signal X (t) is generated. Then, based on Equation (2), the generated second signal X (t) is multiplied by the first signal s (t) generated by the oversampling unit 210 to obtain a constant value. A third signal Y (t) in which a high frequency component of frequency f is added to the sound source signal is generated. By converting the third signal Y (t) into an acoustic signal, the sound source signal and the second signal X (t) are reproduced as sound.

  As shown in Equation (1), the second signal X (t) is not related to the sound source signal or the first signal s (t) obtained by oversampling the sound source signal in terms of the frequency component ratio. is there. That is, the term relating to the sound source signal or the first signal s (t) does not exist in Expression (1). For this reason, the high frequency component generation unit 220 can generate the second signal X (t) including the high frequency component of the desired frequency f without depending on the sound source. In addition, the multiplication unit 230 multiplies the second signal X (t) and the first signal s (t), so that a high-frequency component of a desired frequency f becomes a sound source signal without depending on the sound source. An added third signal Y (t) can be generated. The sound reproduced by the reproducing unit 30 includes a high-frequency component having a desired frequency f that does not depend on the sound source signal, along with the sound source signal.

  In the first embodiment described above, for any one second signal X (t) generated by the high-frequency component generation unit 220, the multiplication unit 230 calculates the third signal Y ( This is particularly useful when generating t). The multiplication unit 230 multiplies the second signal X (t) and the first signal s (t) by Equation (2), thereby adding a high frequency component of one desired frequency f to the sound source signal. A third signal Y (t) can be generated.

[Second Embodiment]
Hereinafter, the configuration of the sound reproducing device 2 according to the second embodiment will be described with reference to FIG. FIG. 5 is a schematic configuration diagram of the sound reproducing device 2 according to the second embodiment. As can be seen from a comparison between FIG. 5 and FIG. 1 described above, the sound reproducing device 2 in the second embodiment mainly includes a high frequency component generation unit 520 (high frequency component generation means) and a multiplication unit 530 (multiplication means). ) Is different from the first embodiment. In the sound reproduction device 2, the high frequency adding unit 50 (high frequency adding device) adds high frequency components of a plurality of desired frequencies (frequency f ₁ ... F _n described later) to the sound signal input from the input unit 10. Then, the reproducing unit 30 reproduces the sound signal to which the plurality of high frequency components are added as sound. Hereinafter, the sound reproducing device 2 will be described in detail with a focus on differences from the case of the first embodiment.

  As shown in FIG. 5, the high frequency component generation unit 520 includes an addition unit 521 and a plurality (n) of level adjustment units (a first level adjustment unit 5221, a second level adjustment unit 5222,..., An nth level adjustment unit). 522n) and a plurality (n) of generators (first generator 5231, second generator 5223,..., N-th generator 523n). n is the number of high frequency components generated by the high frequency component generator 520. Hereinafter, any one of the n level adjustment units is referred to as an “i-th level adjustment unit 522i”, and one generation unit corresponding to the i-th level adjustment unit 522i among the n generation units is referred to as “the i-th level adjustment unit 522i”. i generator 523i ”. i is a natural number of n or less.

The i-th generator 523i is represented by the following mathematical formula (4).
X _1i (t) = 1 + sin (2πf _i t−θ _i ) (4)
Thus, a signal X _1i (t) having a high frequency component of frequency f _i is generated. In Equation (4), f _i represents the frequency of the i-th high-frequency component among n high-frequency components added to the sound source signal later. t represents time. θ _i represents a phase at the frequency f _i . As can be seen from the absence of the term related to the sound source signal or the first signal s (t) in Equation (4), the signal X _1i (t) generated by the i-th generation unit 523i is the sound source signal or the first signal. The signal s (t) is irrelevant in the ratio of frequency components. That is, the signal X _{1i (t),} without depending on the sound source, it is possible to include high-frequency components of the desired frequency f _i.

The i-th generation unit 523i outputs the signal X _1i (t) generated from the above to the i-th level adjustment unit 522i corresponding to the i-th generation unit 523i. That is, the signal X ₁₁ (t) generated by the first generation unit 5231 is output to the first level adjustment unit 5221, and the signal X ₁₂ (t) generated by the second generation unit 5232 is output to the second level adjustment unit 5222. Is done. Similarly, the signal X _1n (t) generated by the first generator 523n is output to the n-th level adjuster 522n.

The i-th level adjustment unit 522i receives the signal X _1i (t) generated by the i-th generation unit 523i. The i-th level adjustment unit 522i is represented by the following mathematical formula (5).
X _i (t) = a _i {1 + sin (2πf _i t−θ _i )} (5)
Accordingly, to weight _{a i} responsive to the frequency _{f i} to the signal _X 1i (t). As a result, the i-th level adjustment unit 522i generates the second signal X _i (t). In Equation (5), a _i is an arbitrary coefficient corresponding to the frequency f _i . The i-th level adjustment unit 522i outputs the second signal X _i (t) generated from the above to the addition unit 521.

により、ｎ個の第ｉレベル調整部５２２ｉから入力されたｎ個の第２の信号Ｘ_ｉ（ｔ）に対する総和Ｚ（ｔ）を求める。数式（６）に音源信号又は第１の信号ｓ（ｔ）に関する項が存在しないことから分かるように、加算部５２１により生成された第２の信号Ｘ_ｉ（ｔ）の総和Ｚ（ｔ）は、音源信号或いは第１の信号ｓ（ｔ）とは周波数成分の割合において無関係である。すなわち、総和Ｚ（ｔ）は、音源に依存することなく、複数の所望の周波数（ｆ_１…ｆ_ｎ）の高周波成分を含むことができる。加算部５２１は、該生成した総和Ｚ（ｔ）を乗算部５３０に出力する。 The adder 521 receives the n second signals X _i (t) generated from the n i th level adjusters 522 _i . The adding unit 521 has the following mathematical formula (6).

Thus, the sum Z (t) for the n second signals X _i (t) input from the n i-th level adjusters 522i is obtained. As can be seen from the absence of the term related to the sound source signal or the first signal s (t) in Equation (6), the sum Z (t) of the second signal X _i (t) generated by the adder 521 is The sound source signal or the first signal s (t) is independent of the frequency component ratio. That is, the sum Z (t) can include high-frequency components of a plurality of desired frequencies (f ₁ ... F _n ) without depending on the sound source. The adder 521 outputs the generated sum Z (t) to the multiplier 530.

により、複数の所望の周波数（ｆ_１…ｆ_ｎ）の高周波成分が付加された第３の信号Ｙ（ｔ）を生成する。 Multiplier 530 multiplies first signal s (t) input from oversampling unit 210 and total sum Z (t) of second signal X _i (t) input from high-frequency component generator 520. Thus, the third signal Y (t) to which the high frequency components of a plurality of desired frequencies (f ₁ ... F _n ) are added is generated. The multiplication unit 530 is configured by the following mathematical formula (3).

Thus, a third signal Y (t) to which high frequency components of a plurality of desired frequencies (f ₁ ... F _n ) are added is generated.

  Next, operations (sound reproduction method and high frequency addition method) performed by the sound reproduction device 2 will be described with reference to FIG. FIG. 6 is a flowchart showing the operation of the sound reproducing device 2.

  First, the input unit 10 inputs, for example, a sound source signal such as audio data recorded on a CD or the like that is generally spread to the high frequency adding unit 50 (step S201).

  Next, the oversampling unit 210 generates a first signal s (t) by oversampling the sound source signal input from the input unit 10. For example, when a frequency component of the frequency f is added to the sound source signal later, the oversampling unit 210 oversamples the sound source signal at a frequency of at least the frequency 2f. The first signal s (t) generated by the oversampling unit 210 is output to the multiplication unit 530 (step S202).

Next, the i-th generation unit 523i generates a signal X _1i (t) having a high frequency component of the frequency f _i based on the above-described equation (4). The i-th generation unit 523i outputs the generated signal X _1i (t) to the i-th level adjustment unit 522i corresponding to the i-th generation unit 523i. each of the n i th generator 523i respectively generates a signal _X 1i (t), and outputs the generated signal _X 1i (t) to the i-th level adjusting portion 522i corresponding to each (Step S203) .

Next, the i-th level adjustment unit 522i attaches a weight a _i corresponding to the signal X _1i (t) input in step S203 based on the above-described equation (5). Each of the n i-th level adjustment units 522i outputs the second signal X _i (t) obtained by adding the weight a _i to the signal X _1i (t) to the addition unit 521 (step S204). .

Next, the adding unit 521 obtains the sum Z (t) of the n second signals X _i (t) input in step S204 based on the above-described equation (6). The adder 521 outputs the obtained sum Z (t) to the multiplier 530 (step S205).

Next, the multiplication unit 530 generates a third signal Y (t) to which high-frequency components of a plurality of desired frequencies (f ₁ ... F _n ) are added based on the above-described equation (3). The multiplying unit 530 adds up the sum Z of the first signal s (t) input from the oversampling unit 210 in step S202 and the second signal X _i (t) input from the adding unit 521 in step S205. by multiplying the (t), the amplitude is changed by the magnitude and the time t of the source signal, a third signal Y (t high-frequency components of a plurality of desired frequencies (f 1 _... f _n) is added ) Is generated. The third signal Y (t) generated by the multiplier 530 is output to the D / A converter 240 (step S206).

  Next, the D / A converter 240 converts the third signal Y (t) input from the multiplier 530 in step S206 into an analog signal. The converted analog signal is converted into an acoustic signal and reproduced as sound (step S207).

Then, the effect | action and effect of the sound reproduction apparatus 2 concerning 2nd Embodiment are demonstrated. According to the second embodiment, each of the i-th generation unit 523i generates a plurality of signals X _1i (t) having a high-frequency component of the frequency f _i according to Equation (4). In addition, each of the i-th level adjustment unit 522i attaches a weight a _i corresponding to each of the signals X _1i (t) based on Expression (5), whereby a plurality of second signals X _i (t ) Is generated. Then, based on Equation (3), the sum Z (t) of the generated second signals X _i (t), the first signal s (t) generated by the oversampling unit 210, and Is multiplied to generate a third signal Y (t) in which high frequency components of a plurality of frequencies (f ₁ ... F _n ) are added to the sound source signal. By converting the third signal Y (t) into an acoustic signal, the sound source signal and the plurality of second signals (X ₁ (t)... X _n (t)) are reproduced as sound.

As shown in Equations (4) to (6), each of the second signals X _i (t) and their sum Z (t) is the first obtained by oversampling the sound source signal or the sound source signal. The signal s (t) is independent of the frequency component ratio. That is, the term relating to the sound source signal or the first signal s (t) does not exist in the equations (4) to (6). Therefore, the high frequency component generation unit 520, without depending on the sound source can also be generated in the plurality of second signals X _i including a high frequency component of the desired frequency f _{i (t).} In addition, the multiplication unit 530 multiplies the total number Z (t) of the plurality of second signals X _i (t) by the first signal s (t) according to the equation (6), thereby obtaining a plurality of frequencies. A third signal Y (t) in which the high-frequency component of (f ₁ ... F _n ) is added to the sound source signal can be generated. Then, the sound is reproduced by the reproduction section 30, together with the sound source signal includes high frequency components of a plurality of frequencies that does not depend on the sound source signal (f 1 _... f _n).

  As mentioned above, although preferred embodiment of this invention was described, it cannot be overemphasized that this invention is not limited to the said embodiment.

  For example, in the above-described embodiment, audio data recorded on, for example, a commonly used CD is assumed as a sound source signal. However, the present invention is not limited to this, and for example, audio used in a regular MP3 player. Data may be assumed.

  In the above embodiment, the D / A conversion unit 240 is configured to be included in the high frequency addition unit 20 or the high frequency addition unit 50. However, the present invention is not limited to this, and the D / A conversion unit 240 is, for example, a reproduction unit. 30 may be included.

It is a structure schematic diagram of a sound reproducing device. It is a hardware block diagram of a sound reproducing device. It is a figure for demonstrating the function of each component of a sound reproducing device. It is a flowchart which shows operation | movement of a sound reproduction apparatus. It is a structure schematic diagram of a sound reproducing device. It is a flowchart which shows operation | movement of a sound reproduction apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 2 ... Sound reproduction apparatus, 10 ... Input part, 20, 50 ... High frequency addition part, 210 oversampling part, 220, 520 ... High frequency component generation part, 230, 530 ... Multiplication part, 240 ... D / A conversion part, 30... Reproduction unit, 521... Addition unit, 5221, 5222, 522n... Level adjustment unit, 5231, 5232, 523n.

Claims (8)

Input means for inputting a sound source signal from which a high-frequency component of a predetermined frequency or higher has been removed in advance;
Oversampling means for generating a first signal by oversampling the sound source signal;
Separately from the sound source signal or the first signal, a high frequency component generating means for generating a second signal having a high frequency component of a constant frequency;
Multiplying means for multiplying the first signal and the second signal to generate a third signal in which a high-frequency component of the constant frequency is added to the sound source signal;
An acoustic reproduction apparatus comprising: reproduction means for reproducing both the sound source signal and the second signal by converting an electrical signal in the third signal into an acoustic signal. Oversampling means for generating a first signal by oversampling a sound source signal from which a high frequency component equal to or higher than a predetermined frequency has been previously removed;
Separately from the sound source signal or the first signal, a high frequency component generating means for generating a second signal having a high frequency component of a constant frequency;
Multiplying means for multiplying the first signal and the second signal to generate a third signal in which a high-frequency component of the constant frequency is added to the sound source signal; and
The oversampling means generates the first signal by oversampling the sound source signal at a frequency that is twice or more the fixed frequency;
The high frequency component generating means is represented by the following formula (1).
X (t) = a {1 + sin (2πft−θ)} (1)
(Wherein, a represents an arbitrary coefficient, f represents the constant frequency, t represents time, and θ represents a phase at the frequency f.)
To generate a second signal X (t) having a high frequency component of a constant frequency f. The multiplication means is represented by the following mathematical formula (2).
Y (t) = a {1 + sin (2πft−θ)} s (t) (2)
(Where s (t) represents the first signal)
By multiplying the first signal s (t) by the second signal X (t), the third signal Y () in which the high frequency component of the constant frequency f is added to the sound source signal. 3. The high frequency adding device according to claim 2, wherein t) is generated. The high frequency component generating means generates a plurality of second signals X (t) having high frequency components according to the mathematical formula (1),
The multiplication means is represented by the following mathematical formula (3).

(Where n is the number of the plurality of generated second signals, i is an identifier for any one of the n second signals, and is a natural number equal to or less than n, and a _i is (An arbitrary coefficient in the i-th second signal is represented, f _i represents a frequency in the i-th second signal, and θ _i represents a phase in the frequency f _i .)
By multiplying the first signal s (t) by the sum of the plurality of second signals, a third signal Y (t) in which a plurality of high frequency components are added to the sound source signal is generated. The high-frequency addition apparatus according to claim 2 or 3, wherein An input step in which the input means receives a sound source signal from which a high frequency component equal to or higher than a predetermined frequency has been previously removed; and
An oversampling step in which an oversampling unit generates a first signal by oversampling the sound source signal;
A high frequency component generating means for generating a second signal having a high frequency component of a constant frequency separately from the sound source signal or the first signal;
A multiplying step for multiplying the first signal by the second signal to generate a third signal in which a high frequency component of the constant frequency is added to the sound source signal;
A sound reproduction method comprising: a reproduction step of reproducing the sound source signal and the second signal together by reproducing an electrical signal in the third signal into an acoustic signal. An oversampling step in which an oversampling unit generates a first signal by oversampling a sound source signal from which a high frequency component equal to or higher than a predetermined frequency has been previously removed;
A high frequency component generating means for generating a second signal having a high frequency component of a constant frequency separately from the sound source signal or the first signal;
A multiplying step of multiplying the first signal and the second signal to generate a third signal in which a high-frequency component of the constant frequency is added to the sound source signal;
In the oversampling step, the first signal is generated by oversampling the sound source signal at a frequency twice or more the fixed frequency,
In the high frequency component generation step, the following mathematical formula (1)
X (t) = a {1 + sin (2πft−θ)} (1)
(Wherein, a represents an arbitrary coefficient, f represents the constant frequency, t represents time, and θ represents a phase at the frequency f.)
To generate a second signal X (t) having a high-frequency component of a constant frequency f. In the multiplication step, the following formula (2)
Y (t) = a {1 + sin (2πft−θ)} s (t) (2)
(Where s (t) represents the first signal)
By multiplying the first signal s (t) by the second signal X (t), the third signal Y () in which the high frequency component of the constant frequency f is added to the sound source signal. 7. The high frequency applying method according to claim 6, wherein t) is generated. In the high frequency component generation step, a plurality of second signals X (t) having high frequency components are generated according to the mathematical formula (1),
In the multiplication step, the following mathematical formula (3)

(Where n is the number of the plurality of generated second signals, i is an identifier for any one of the n second signals, and is a natural number equal to or less than n, and a _i is (An arbitrary coefficient in the i-th second signal is represented, f _i represents a frequency in the i-th second signal, and θ _i represents a phase in the frequency f _i .)
By multiplying the first signal s (t) by the sum of the plurality of second signals, a third signal Y (t) in which a plurality of high frequency components are added to the sound source signal is generated. The high frequency applying method according to claim 6 or 7, wherein:

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