JP6089651B2 - Sound processing apparatus, sound processing apparatus control method, and program - Google Patents

Description

  The present invention relates to a sound processing device, a control method for a sound processing device, and a program for emphasizing a fundamental tone by emphasizing overtones when a speaker with low bass reproduction capability is used.

  Conventionally, as this type of technology, means for detecting the fundamental level of a musical tone of a predetermined scale from the original sound, means for extracting the frequency components of the fundamental tone and harmonics from the original sound, and the frequency components below the fundamental tone from the extracted frequency component Means for removing frequency components higher than harmonics contained in a musical tone of a predetermined scale, means for adjusting the level of a musical tone from which frequency components have been removed according to the detected fundamental level, and amplifying the musical tone after level adjustment There is known a musical tone emphasizing device including a means for adding to the original sound (for example, Patent Document 1). With this configuration, the musical sound emphasizing apparatus can enhance a desired musical sound with a natural sound without breaking the harmonic balance. Further, even a speaker with low bass reproduction capability can make a user perceive that a musical sound is emphasized by enhancing harmonics.

WO2009 / 004718

  However, since the degree of overtone emphasis is controlled by the fundamental sound level in the invention of Patent Document 1, the integer order overtones, that is, the bass drum sounds, are also obtained for musical sounds having no overtone components such as bass drum sounds. Components other than frequency components (components of other musical instruments) are emphasized, and there is a possibility that the tone of the musical tone is destroyed.

  In view of the above problems, an object of the present invention is to provide a sound processing apparatus, a sound processing apparatus control method, and a program that can emphasize bass without destroying the tone color of a musical tone.

The sound processing apparatus of the present invention includes a harmonic overtone extraction unit that extracts a harmonic over the fundamental tone that is the target of the auditory illusion from the original sound, and if the extracted harmonic overtone satisfies a predetermined condition, the fundamental tone that is the subject of the auditory illusion A determination unit that determines that it is a fundamental tone of a musical tone having a component, an enhancement processing unit that performs enhancement processing of the harmonics extracted by the harmonic overtone extraction unit according to a determination result of the determination unit, and after the enhancement processing by the enhancement processing unit An addition unit that adds overtones and original sounds is provided.

In the above sound processing apparatus, enhancement processing section, by the determination unit, fundamental tone to be auditory illusion, if it is determined that the fundamental tone of a musical tone with harmonics, have rows enhancement of harmonics, the adding unit If the determination unit determines that the fundamental tone that is the target of the auditory illusion is a fundamental tone that does not have a harmonic component, it outputs only the original tone without adding the extracted harmonics and the original tone. It is characterized by that.

  In the above sound processing device, the overtone extraction unit extracts a plurality of overtones having different orders with respect to the fundamental tone that is the target of the auditory illusion, and the determination unit, when the plurality of overtones extracted satisfy a predetermined condition, It is characterized in that it is determined that the fundamental tone to be subjected to the auditory illusion is a fundamental tone of a musical tone having a harmonic component.

  In the above sound processing apparatus, the predetermined condition includes that the amplitude values of a plurality of overtones are all maximal on the frequency axis.

  In the above sound processing apparatus, the predetermined condition is that the amplitude value of the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) and the amplitude value of the (N + 1) th order harmonic maximum. It is characterized by including that a difference is below a predetermined value.

  In the above sound processing apparatus, the predetermined condition is that the amplitude value of the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) is greater than the amplitude value of the (N + 1) th order harmonic. It is characterized by including large.

  In the above sound processing apparatus, the predetermined condition includes a correlation between time transitions of fundamental values and amplitude values of a plurality of overtones.

The control method of the sound processing device of the present invention includes a harmonic overtone extraction step for extracting a harmonic over the fundamental tone that is the target of the auditory illusion from the original sound, and a fundamental tone that is subject to the auditory illusion when the extracted harmonic overtone satisfies a predetermined condition Are determined in the determination step that is a fundamental tone of a musical tone having a harmonic component, the enhancement processing step that performs the enhancement processing of the harmonics extracted in the harmonic extraction step according to the determination result of the determination step, and the enhancement processing step An addition step of adding the emphasized overtone and the original sound is performed.

  A program according to the present invention causes a computer to execute each step in the above-described sound processing apparatus control method.

It is a block diagram of the reproducing | regenerating apparatus which concerns on one Embodiment of this invention. It is a functional block diagram of an audio | voice signal processing part. It is a figure which shows an example of a harmonic extraction result in the case of performing a harmonic emphasis process. It is a figure which shows an example of a harmonic extraction result when not performing a harmonic emphasis process. It is a figure which shows an example of a harmonic extraction result when not performing a harmonic emphasis process. It is a flowchart which shows the flow of a harmonic emphasis process. It is a block diagram of the reproducing | regenerating apparatus which concerns on the modification of this invention. It is a block diagram of the reproducing | regenerating apparatus which concerns on the other modification of this invention.

  Hereinafter, a sound processing device, a control method for the sound processing device, and a program according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a block diagram of a playback apparatus 10 to which the sound processing apparatus of the present invention is applied. The playback apparatus 10 includes, as main components, an input interface (hereinafter referred to as “input I / F”) 11, a main control unit 12, an internal memory 13, an operation unit 14, an audio signal processing unit 15, an amplifier 16, a speaker. 17 is provided. The “sound processing device” in the claims corresponds to the audio signal processing unit 15.

  The input I / F 11 inputs music data and music information provided from the host device 20. As the host device 20, a personal computer, a mobile terminal (including a smart phone, a mobile phone, a PDA, etc.), a server on the Web, a server on a LAN network, and the like are conceivable. The host device 20 has a music analysis processing unit 21. The music analysis processing unit 21 analyzes music data and generates analysis data. As analysis data, music feature quantities such as beat position information, BPM (Beats Per Minute) information, key (key) information, and genre information are generated. These are used in the playback apparatus 10 for music selection (selection of music specifying a genre or key), beat position synchronization processing, audio signal processing (overtone enhancement processing), and the like.

  The host device 20 reproduces, together with the music data, analysis data that is an analysis result of the music analysis processing unit 21 and accompanying information (meta information such as a song title, artist name, and album name) attached to the music. 10 to provide. In the following description, analysis data and accompanying information are collectively referred to as music information. The data provided by the host device 20 may be stored in an external storage medium such as a USB memory and read by the playback device 10.

  The main control unit 12 includes a CPU (Central Processing Unit) and a microcomputer, and controls each unit in the playback device 10. The internal memory 13 stores music data and music information provided from the host device 20. The internal memory 13 is also used for storing various control programs and control data. The operation unit 14 includes operation keys and a remote controller provided in the main body of the playback apparatus 10 and is used by the user to perform various operations and settings.

  The audio signal processing unit 15 processes the music data input from the input I / F 11 or the music data read from the internal memory 13 (audio signal = original sound obtained by decoding the music data). In the present embodiment, the audio signal processing unit 15 performs overtone emphasis processing mainly for auditory illusion of bass (fundamental sound). Details will be described later. The amplifier 16 amplifies the audio signal processed by the audio signal processing unit 15. The speaker 17 reproduces the audio signal amplified by the amplifier 16.

  The amplifier 16 may be built in the speaker 17. The audio signal processing unit 15 may be realized by software such as a DSP (Digital Signal Processor) or may be realized by an analog device. Further, headphones may be mounted instead of the speakers 17. Further, the speaker 17 may not be provided in the playback apparatus 10 but may be configured as a separate body.

  Next, the details of the audio signal processing unit 15 according to the first embodiment will be described with reference to FIG. The audio signal processing unit 15 includes a harmonic overtone extraction unit 31, a determination unit 32, an enhancement processing unit 33, and an addition unit 34. The harmonic overtone extraction unit 31 extracts an integer overtone (hereinafter simply referred to as “overtone”) with respect to a predetermined fundamental tone in the audio signal (original sound) input to the audio signal processing unit 15.

  In the present embodiment, as a predetermined fundamental tone, a low-frequency fundamental tone (frequency corresponding to the scale of a musical instrument that reproduces a bass tone, such as a bass) is extracted. Here, the auditory illusion includes a component of the fundamental frequency f when a sound composed of signals (overtone groups) of 2f, 3f, 4f... That are harmonics of the signal (fundamental sound) of the fundamental frequency f is heard. Even if not, it refers to an auditory psychological phenomenon (missing fundamental phenomenon) in which the sound of the frequency f feels as if it is being reproduced. That is, the playback device 10 according to the present embodiment uses this psychoacoustic phenomenon to cut and cut the low range below the playback limit of the speaker 17 when the music is played by the speaker 17 having low bass playback capability. By emphasizing the harmonics corresponding to the sound (fundamental sound), the fundamental sound is audible. However, for a musical sound that does not have a harmonic component such as a bass drum sound, if the frequency component corresponding to that harmonic is emphasized, components other than the frequency component that constitutes the bass drum sound (components of other instruments) The tone is emphasized and the tone of the musical tone is destroyed. Therefore, depending on the state of the harmonics of the fundamental tone that is the target of the auditory illusion, musical notes that do not have harmonic components (bass drum sounds, etc.) are not emphasized, and those that have harmonic components (bass sounds, etc.) are not used. By performing harmonic overtone enhancement only on the bass, it is possible to enhance the bass without destroying the tone of the musical tone. Hereinafter, the overtone emphasis process for emphasizing only the musical tone having the overtone component will be described in detail.

  When the overtone extracted by the overtone extraction unit 31 satisfies a predetermined condition, the determination unit 32 determines that the fundamental tone that is the target of the auditory illusion is a fundamental tone of a musical tone having a harmonic component. In the present embodiment, the harmonic overtone extraction unit 31 extracts the secondary overtone and the tertiary overtone. Of course, harmonics of other orders may be extracted, but it is preferable to extract those of lower orders. The number of overtones to be extracted is also arbitrary.

  Note that the number and order of harmonics to be extracted may be specified (selected) by the user using the operation unit 14, and the number and order of harmonics to be extracted are determined based on music information input from the host device 20. You may decide.

  Here, the “predetermined condition” serving as a criterion for determining whether or not there is a harmonic component will be described. In this embodiment, determination is performed based on three conditions. The first condition is “on the frequency spectrum obtained by frequency-converting the original sound (on the frequency axis), the amplitude values of the plurality of overtones extracted are all maximal”. A specific example will be described. 3 to 5 show frequency spectra with the horizontal axis representing frequency and the vertical axis representing amplitude value (signal level). In FIG. 3, reference symbol P01 indicates the frequency of the fundamental tone (scale D1) (and the amplitude value of the frequency spectrum corresponding to the fundamental frequency), and reference symbols P02 and P03 indicate secondary components for the fundamental tone (scale D1), respectively. The frequency of the harmonic and the third harmonic is shown. As shown in the figure, when both the second harmonic and the third harmonic are maximum, it is determined that the first condition is satisfied. Note that “maximum” means that the amplitude value of the target harmonic is larger than the amplitude value of the surrounding frequency components.

  On the other hand, FIG. 4 illustrates a case where the first condition is not satisfied. In the same figure, the code | symbol P11 has shown the frequency of the fundamental tone (tone B1), and the codes | symbols P12 and P13 have shown the frequency of the 2nd overtone and the 3rd overtone with respect to the fundamental tone (scale B1), respectively. In the example of the figure, since the second harmonic and the third harmonic are not maximal, it is determined that the first condition is not satisfied. Although not particularly illustrated, it is determined that the first condition is not satisfied even when one of the second harmonic and the third harmonic is not maximal.

  Subsequently, the second condition is that a difference between amplitude values of “the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) and the (N + 1) th order harmonic is a predetermined value or less. "Being that". Here, the “predetermined value” means a predetermined value (a predetermined value stored in the internal memory 13). In the example of FIG. 3, since the difference L1 in the amplitude value between the maximum point of the second harmonic and the maximum point of the third harmonic indicated by symbols P02 and P03 is small (below a predetermined value), the second condition is Judge that it satisfies. On the other hand, FIG. 5 illustrates a case where the second condition is not satisfied. In the same figure, the code | symbol P21 has shown the frequency of the fundamental tone (scale G1), and the codes | symbols P22 and P23 have shown the frequency of the 2nd overtone and the 3rd overtone with respect to the fundamental tone (scale G1), respectively. In the example shown in the figure, although both the second harmonic and the third harmonic are maximum, it is determined that the second condition is not satisfied because the difference L2 between the amplitude values is large (beyond a predetermined value). To do.

  The “predetermined value” that is the determination threshold value of the second condition is not limited to a fixed value as described above, and may be a value designated (selected) by the user. Alternatively, the “predetermined value” may be variably set based on the music information input from the host device 20.

  Subsequently, the third condition is that “the amplitude value of the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) is greater than the amplitude value of the (N + 1) th order harmonic maximum point. Is. In the example of FIG. 3, since the amplitude value of the maximum point of the second harmonic overtone indicated by the symbol P02 is larger than the amplitude value of the maximum point of the third harmonic overtone indicated by the symbol P03, it is determined that the third condition is satisfied. To do. On the other hand, in the example of FIG. 5, the amplitude value of the maximum point of the second harmonic overtone indicated by the symbol P22 is smaller than the amplitude value of the maximum point of the third harmonic overtone indicated by the symbol P23, and therefore the third condition is satisfied. Judge that it is not.

  As described above, in the determination unit 32, when a plurality of overtones extracted by the overtone extraction unit 31 satisfy all of the first condition to the third condition, the fundamental tone that is the target of the auditory illusion has overtone components. It is determined that it is the fundamental tone of the musical tone that it has.

  The enhancement processing unit 33 performs an enhancement process on the harmonics extracted by the harmonic extraction unit 31 when the determination unit 32 determines that the fundamental tone to be auditory illusion is a musical tone fundamental tone having a harmonic component. It is. As shown in FIG. 2, the enhancement processing unit 33 includes a level adjustment unit 41 for the second harmonic, a level adjustment unit 42 for the third harmonic, a harmonic addition unit 43, and a switch 44. The level adjusters 41 and 42 perform level adjustment (amplification) of the extracted second harmonic and third harmonic, respectively.

  Note that the level adjustment amount (level adjustment coefficient) may be the same value or a different value in each of the level adjustment units 41 and 42. Further, it may be a predetermined value (a predetermined value stored in the internal memory 13) or a value designated (selected) by the user. Alternatively, the level adjustment amount (level adjustment coefficient) may be variably set based on the music information input from the host device 20.

  The harmonic overtone adding unit 43 adds overtones after the level adjustment by the level adjusting units 41 and 42. Further, the switch 44 switches ON / OFF according to the determination result of the determination unit 32. Specifically, when the determination unit 32 determines that the fundamental tone to be subjected to the auditory illusion has a harmonic component, the determination unit 32 sets the ON state. When the determination unit 32 determines that the fundamental component does not have a harmonic component, the determination unit 32 sets the OFF state.

  On the other hand, the adding unit 34 adds the input original sound (audio signal) and the overtone after the enhancement process. With the above configuration, when the determination unit 32 determines that the fundamental tone that is the target of the auditory illusion does not have a harmonic component, the audio signal processing unit 15 outputs only the original sound and determines that it has the harmonic component. In the case, the result of adding the original sound and the overtone after the enhancement process is output.

  Next, the flow of overtone enhancement processing of the playback apparatus 10 will be described with reference to the flowchart of FIG. When the reproduction apparatus 10 (audio signal processing unit 15) acquires the original sound (music data) from the higher-level apparatus 20 (S01), the reproduction apparatus 10 (audio signal processing unit 15) extracts overtones (second overtones and third overtones) with respect to the fundamental sound that is the target of auditory illusion ( S02). Then, it is determined whether or not the amplitude values of the second harmonic and the third harmonic are maximum (whether or not the first condition is satisfied) (S03). In the case of S03: Yes, it is subsequently determined whether or not the difference between the amplitude values of the second harmonic and the third harmonic is equal to or smaller than a predetermined value (whether or not the second condition is satisfied) (S04). Further, in the case of S04: Yes, it is determined whether or not the amplitude value of the secondary harmonic is larger than the amplitude value of the tertiary harmonic (whether or not the third condition is satisfied) (S05). In the case of S05: Yes (when all of the first condition to the third condition are satisfied), the harmonic overtone extracted in S01 is emphasized (S06), and the overtone enhancement processing is terminated. In the case of S03: No, S04: No, S05: No, the harmonic overtone extracted in S01 is not emphasized (S07), and the overtone emphasis processing is terminated.

  As described above, the playback apparatus 10 according to the present embodiment determines whether or not the fundamental tone that is the target of the auditory illusion has a harmonic component, and performs the harmonic enhancement process only when it is determined that the fundamental component has the harmonic component. . In other words, no emphasis processing is performed for harmonics of percussion instrument sounds such as bass drum sounds that do not have harmonic components. For this reason, components other than the frequency components that make up the bass drum sound (components of other instruments) that occur when inharmonic enhancement processing including bass drum sound is performed indiscriminately are emphasized, and the tone of the musical tone is emphasized. The problem that it collapses can be solved.

  Further, by determining whether or not there is a harmonic component based on three conditions, a more accurate determination result can be obtained. In addition, this makes it possible to more reliably realize high-quality bass reproduction using the missing fundamental phenomenon even when a speaker having a low bass reproduction capability such as a small-diameter speaker is used.

  In the above embodiment, the determination unit 32 determines the first condition to the third condition as the AND condition, but may determine it as an OR condition. Also, the user may be able to select whether to determine as an AND condition or an OR condition. Further, instead of determining all of the first to third conditions, the determination may be made only for some conditions. In this case, the user may select a target condition.

  Further, based on the music information input from the host device 20, it may be variably set whether the first condition to the third condition is determined as an AND condition or an OR condition. Alternatively, the target condition may be variably set based on the input music information.

  In addition, as a determination condition of the determination unit 32, it may be added as a fourth condition that there is a correlation between temporal transitions of the amplitude values of the fundamental tone and the harmonics. This means that for musical tones that have harmonics such as bass, there is a correlation between the time transitions of the amplitude values of the fundamental and harmonics, and for musical tones that do not have harmonics such as bass drum, there is no correlation between the fundamental and harmonics. Is focused on. Here, “correlation” means that, for example, when the base sound is played, the amplitude values of the fundamental tone and the harmonics are both increased, and when the musical instrument is finished being played, both the amplitude values are decreased. Therefore, when the fourth condition is added as the determination condition, the determination unit 32 determines a change in the frequency spectrum with time. That is, the frequency spectrum for a plurality of frames is stored in a buffer (not shown), and the correlation between the time transitions of the fundamental tone and the harmonic overtone is examined. For example, when the amplitude values of the second overtone and the third overtone both decrease with the passage of time, it is determined that “there is a correlation between the fundamental tone and the overtone”. Further, in this case, it is regarded as “a musical tone having overtones”, and overtone enhancement processing is performed. Note that the fourth condition may be added as an AND condition to the first to third conditions, or may be added as an OR condition.

  Further, in the above embodiment, the determination unit 32 determines that the first condition is satisfied when both the second harmonic and the third harmonic are maximum, but when only one of them is the maximum, It may be determined that the first condition is satisfied.

  Further, when the determination is performed by extracting three or more harmonics, only one of the difference between the amplitude values of the second harmonic and the third harmonic, for example, the difference between the amplitudes of the third harmonic and the fourth harmonic is included. If it is less than or equal to the predetermined value, it may be determined that the second condition is satisfied. Further, if only one of the amplitude value of the second harmonic> the amplitude value of the third harmonic, the amplitude value of the third harmonic> the amplitude value of the fourth harmonic is satisfied, the third condition may be determined to be satisfied. Good.

  In the above embodiment, the low frequency band below the reproduction limit of the speaker 17 is cut to emphasize the harmonics corresponding to the cut sound (fundamental sound). However, the fundamental sound is not necessarily included in the cut sound. It does not have to be included. In addition, it is not always necessary to cut a low range below the reproduction limit.

  Further, in the above embodiment, harmonics are extracted from the fundamental spectrum that is the target of the auditory illusion from the frequency spectrum obtained by frequency conversion of the original sound. However, harmonics may be extracted based on the time axis instead of the frequency axis.

[Modification 1]
Next, a modification of the present invention will be described with reference to FIGS. FIG. 7 is a block diagram of the playback apparatus 10 according to the first modification. In the first modification, the music analysis processing unit 18 is added as compared with the playback device 10 (see FIG. 1) of the first embodiment. The music analysis processing unit 18 performs music data analysis processing and has the same function as the music analysis processing unit 21 of the first embodiment. That is, the playback device 10 according to the modification has a configuration in which only the music data is acquired from the host device 20.

  As described above, according to the first modification of the present invention, since the music analysis processing unit 18 is provided and the music can be analyzed by the playback device 10 itself, only the music data may be acquired from the host device 20.

[Modification 2]
FIG. 8 is a block diagram of the playback apparatus 10 according to the second modification. In the second modification, the host device 20 has a music analysis processing unit 21 and an audio signal processing unit 22. The audio signal processing unit 22 performs processing of an audio signal obtained by decoding music data, and has the same function as the audio signal processing unit 15 of the first embodiment. That is, the playback device 10 according to the modification 2 is configured to acquire processed music data (audio signal) that has been subjected to the harmonic emphasis processing from the higher-level device 20. As in the first embodiment, since the host device 20 is also provided with the music analysis processing unit 21, the playback device 10 also acquires music information including analysis data and accompanying information by the music analysis processing unit 21. . On the other hand, the function of the playback device 10 includes an input I / F 11 that performs a function of transmitting and receiving music data and music information, a main control unit 12, and an operation unit 14, and the amplifier 16 and the speaker 17 are separated. ing. Of course, the playback apparatus 10 may be configured to include the amplifier 16 and the speaker 17.

  Thus, according to the second modification of the present invention, the host device 20 can be provided in a server on the Web or a server on the LAN network. That is, the sound processing apparatus of the present invention can be used as cloud computing.

  In addition, it is possible to provide each component and each processing process of the reproducing | regenerating apparatus 10 shown to said embodiment and modification as a program. Further, the program can be provided by being stored in various storage media (CD-ROM, flash memory, etc.). That is, a program for realizing each component or each processing step of the playback apparatus 10 and a storage medium storing the program are also included in the scope of the right of the present invention.

  In the above-described embodiment and modification, the sound processing apparatus of the present invention is applied to the playback apparatus 10 or the host apparatus 20, but the present invention is not limited to the playback dedicated apparatus or the music providing dedicated apparatus. The playback device 10 or the host device 20 may be realized as a function of another electronic device such as a tablet terminal, a mobile phone, or a car navigation device. Other modifications can be made as appropriate without departing from the scope of the present invention.

  DESCRIPTION OF SYMBOLS 10 ... Playback apparatus 11 ... Input interface 12 ... Main control part 13 ... Internal memory 14 ... Operation part 15 ... Audio | voice signal processing part 16 ... Amplifier 17 ... Speaker 20 ... High-order apparatus 21 ... Music analysis processing part 31 ... Overtone extraction part 32 ... Determination unit 33 ... enhancement processing unit 34 ... addition unit 41 ... secondary harmonic level adjustment unit 42 ... tertiary harmonic level adjustment unit 43 ... harmonic addition unit 44 ... switch

Claims (9)

A harmonic overtone extractor that extracts overtones from the fundamental sound for the fundamental tone that is the target of the auditory illusion;
When the extracted overtone satisfies a predetermined condition, the determination unit determines that the fundamental tone to be subjected to the auditory illusion is a fundamental tone of a musical tone having a harmonic component;
An emphasis processing unit that performs emphasis processing of the harmonics extracted by the harmonic extraction unit according to the determination result of the determination unit;
A sound processing apparatus comprising: an addition unit that adds overtones after enhancement processing by the enhancement processing unit and the original sound. The enhancement processing unit, by the determination unit, fundamental tone to be the auditory illusion, if it is determined that the fundamental tone of a musical tone with harmonics, have rows enhancement processing of the harmonic,
The adding unit adds the extracted overtone and the original sound when the determination unit determines that the fundamental tone to be subjected to the auditory illusion is a fundamental tone of a musical tone having no overtone component. The sound processing apparatus according to claim 1 , wherein only the original sound is output . The harmonic overtone extraction unit extracts a plurality of overtones having different orders with respect to the fundamental tone to be subjected to the auditory illusion,
3. The determination unit according to claim 2, wherein when the plurality of overtones extracted satisfy a predetermined condition, the base tone to be subjected to the auditory illusion is determined to be a base tone of a musical tone having a harmonic component. The sound processing apparatus according to 1.   The sound processing apparatus according to claim 3, wherein the predetermined condition includes that amplitude values of the plurality of overtones are all maximal on a frequency axis.   The predetermined condition is that a difference between the amplitude value of the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) and the amplitude value of the (N + 1) th order harmonic is less than a predetermined value. The sound processing apparatus according to claim 4, further comprising:   The predetermined condition includes that the amplitude value of the extracted Nth order harmonic (where N is an integer satisfying N ≧ 2) is larger than the amplitude value of the (N + 1) th order harmonic maximum. The sound processing apparatus according to claim 5, characterized in that:   The sound processing apparatus according to claim 6, wherein the predetermined condition includes a correlation between time transitions of amplitude values of the fundamental sound and the plurality of overtones. A harmonic overtone extraction step for extracting a harmonic overtone from the original sound with respect to the fundamental tone to be auditory illusion;
When the extracted overtone satisfies a predetermined condition, a determination step for determining that the fundamental tone to be subjected to the auditory illusion is a fundamental tone of a musical tone having a harmonic component;
An emphasis processing step for emphasizing the harmonics extracted by the harmonic extraction step according to the determination result of the determination step;
A control method for a sound processing apparatus , comprising: an addition step of adding the overtone emphasized in the enhancement processing step and the original sound.   The program for making a computer perform each step in the control method of the sound processing apparatus of Claim 8.

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