Vibrato control device and program

Abstract

This invention provides a vibrato control device and program that enhance vocal expression by adding vibrato to the voice. [Solution] In the vibrato control system 1, the vibrato control device 10 includes a current application unit 160 that applies a stimulating current to an electrode unit 20 having a positive electrode 21 and a negative electrode 22 and attached to the skin surface of the throat, and a waveform control unit 109 that controls at least one of the frequency and amplitude of the stimulating current based on the desired vibrato state.

Description

[Technical Field]

[0001] The present invention relates to a vibrato control device and a program. [Background Art]

[0002] When singing a song, if vibrato can be applied to the singing voice, the enjoyment of singing can be increased. In relation to this, conventionally, methods such as speech synthesis of vibrato based on music information and the like have been proposed (see, for example, Patent Document 1). [Prior Art Literature] [Patent Literature]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2016-51035 [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] However, with conventional techniques, it has not been possible to generate vibrato in the singing voice of the person who is singing. It is preferable if vibrato can be applied to the singing voice of the person who is singing without special vibrato practice, because this enhances the expressive power of the singing.

[0005] An object of the present invention is to provide a vibrato control device and a program that can apply vibrato to a voice and enhance expressive power. [Means for Solving the Problem]

[0006] One aspect of the present invention is a vibrato control device comprising: a current applying unit that has a positive electrode and a negative electrode, and supplies a stimulation current to an electrode unit attached to the skin surface of the throat; and a waveform control unit that controls at least one of the frequency and the amplitude of the stimulation current based on a state of vibrato desired to be generated.

[0007] One aspect of the present invention is a program for causing a computer in a vibrato control device, which provides control information for the stimulating current, to perform the following actions: calculate at least one of the frequency and amplitude of the stimulating current based on the desired vibrato state, and output information indicating at least one of the calculated frequency and amplitude to the vibrato control device as control information. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a vibrato control device and program that can add vibrato to the voice and enhance its expressiveness. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the device configuration of the vibrato control system of this embodiment. [Figure 2] This figure shows an example of the configuration of the electrode section in this embodiment. [Figure 3] This figure shows an example of an electrode attached to the skin surface of the throat. [Figure 4] This figure shows an example of the current value calibration operation flow of the vibrato control device of this embodiment. [Figure 5] This figure shows an example of the electrode selection results used for current value calibration in this embodiment. [Figure 6] This figure shows an example of the unpleasant current value registration screen for this embodiment. [Figure 7] This figure shows an example of the operation flow for electrode combination search in this embodiment. [Figure 8] This figure shows an example of a set of positive and negative electrodes according to this embodiment. [Figure 9] This figure shows an example of the time waveform of the fundamental frequency in vibrato control according to this embodiment. [Figure 10] This figure shows an example of the amplitude spectrum in vibrato control according to this embodiment. [Figure 11] This figure shows another example of electrode combinations during the stimulation position setting process in this embodiment. [Figure 12] This figure shows an example of the flow of vibrato control processing by the vibrato control system of this embodiment. [Figure 13] This figure shows an example of vibrato speed and modulation range. [Figure 14] This figure shows an example of experimental results of singing using the vibrato control device of this embodiment. [Modes for carrying out the invention]

[0010] The vibrato control system 1 of this embodiment will be described with reference to the drawings. The embodiments described below are merely examples, and the embodiments to which the present invention is applied are not limited to the embodiments described below. In all the figures used to illustrate the embodiments, components with the same function are given the same reference numerals, and repeated explanations are omitted. Furthermore, in this application, "based on XX" means "based on at least XX," and includes cases where it is based on another element in addition to XX. Also, "based on XX" is not limited to cases where XX is used directly, but also includes cases where it is based on something that has been calculated or processed from XX. "XX" is any element (for example, any information).

[0011] [overview] Vibrato plays an important role in impression evaluation of singing and instrumental performance. Changing the speed of vibrato is considered effective to make the singing resemble the singer's own voice or obtain an impressive vibrato, but realizing vibrato itself inherently requires high skill. Therefore, in the present embodiment, vibrato is generated by selectively applying electrical stimulation to the throat, preferably the larynx, and the speed of the vibrato is controlled. As a result, control of vibrato whose speed corresponds to a stimulation frequency in the 4-14 [Hz] band, including the 4-7 [Hz] range recognized as natural vibrato, is achieved.

[0012] Vibrato is a periodic fluctuation of the fundamental frequency (F0). Vibrato is represented by two parameters: speed and modulation width. The speed is the number of fluctuations of the fundamental frequency occurring per unit time, and the modulation width is the range of fluctuation centered on the average pitch in a vibrato section. Generally, it is perceived that natural vibrato has a speed of about 4-7 [Hz] and a modulation width in the range of 0.5-2.0 semitones (50-200 cents).

[0013] Applying vibrato broadens the range of expression in singing and instrumental performance. High evaluation of singing can be obtained by applying vibrato of an appropriate speed. In addition, vibrato that is too fast or too slow can give various impressions, such as tension or an impression of low vitality. However, realizing vibrato itself requires high skill, and controlling its speed is extremely difficult. Conventionally, it has been suggested that vibrato can be generated by cervical electrical stimulation using surface electrodes, but this has been limited to qualitative evaluation, and there are problems with the size and position of the electrodes.

[0014] For example, it is known that vibrato can be produced by electrically stimulating the abdomen or neck via surface electrodes. However, prior studies focused on the construction of user interfaces and subjective evaluation by subjects, and no evaluation of voice waveforms was performed. In addition, for neck stimulation, electrodes of several tens of millimeters square were arranged obliquely at the upper and lower parts of the anterior neck to cover the cricothyroid muscle (Cryco Thyroid muscle; CT muscle). This arrangement position was chosen because it was expected that contracting the CT muscle would stretch the vocal cords and periodically increase the fundamental frequency of the voice. However, since the gap where the CT muscle is exposed from the cartilage is at most 7 mm, when an electrode of several tens of millimeters square is arranged to cover the CT muscle, accurate stimulation is difficult.

[0015] Therefore, in the present embodiment, this specification quantitatively demonstrates that vibrato can be produced and its speed can be controlled by selectively applying electrical stimulation to a narrow area around the CT muscle. Specifically, in the present embodiment, a multi-point myoelectric stimulation system is used to identify an appropriate stimulation position for producing vibrato, and the speed of vibrato is controlled by changing the stimulation frequency. Then, the vibrato speed and modulation width were obtained from the recorded voice data, and it was evaluated that such control can be achieved.

[0016] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Figure 1 is a diagram showing an example of the device configuration of a vibrato control system 1 according to the present embodiment. The vibrato control system 1 is configured to include a vibrato control device 10 and an electrode unit 20.

[0017] The vibrato control device 10 includes an arithmetic unit 100, a storage unit 150, and a current applying unit 160. The arithmetic unit 100 includes a central processing unit (CPU), operates based on programs and data stored in the storage unit 150, and provides various functions. The storage unit 150 is composed of, for example, a hard disk drive or semiconductor memory (flash memory, RAM, ROM), and stores various types of information, such as programs and data read by the arithmetic unit 100. The storage unit 150 may also be implemented by a virtual storage device, such as a cloud server, located outside the vibrato control device 10.

[0018] The calculation unit 100 includes, as its functional units, a stimulus state acquisition unit 101, a current value control unit 102, a voice acquisition unit 103, an acceleration acquisition unit 104, a determination unit 105, an electrode selection unit 106, a music information acquisition unit 107, a generation unit 108, and a waveform control unit 109.

[0019] The current application unit 160 is composed of a constant current circuit or the like that can control the current value, and supplies current to the electrode unit 20 based on the control of the calculation unit 100.

[0020] The electrode section 20 includes a positive electrode 21 and a negative electrode 22. The electrode section 20 may be configured in a one-to-one configuration, with one electrode 201 each for the positive electrode 21 and the negative electrode 22; a many-to-one configuration, with multiple electrodes 201 as the positive electrode 21 and one electrode 201 as the negative electrode 22; a one-to-many configuration, with one electrode 201 as the positive electrode 21 and multiple electrodes 201 as the negative electrode 22; or a many-to-many configuration, where both the positive electrode 21 and the negative electrode 22 have multiple electrodes 201. Figure 2 shows an example of a many-to-many configuration of the electrodes 201 in the electrode section 20.

[0021] Figure 2 shows an example of the configuration of the electrode section 20 of this embodiment. The electrode section 20 comprises a plurality of electrodes 201. The electrodes 201 are arranged in a matrix along two axes, for example, the horizontal x-axis direction and the vertical y-axis direction. The electrodes 201 are also called small electrodes.

[0022] The electrode unit 20 is a multi-point muscle electrical stimulation electrode. For example, the electrode 201 is an elliptical electrode with a short diameter of 2 mm and a long diameter of 3 mm. The electrode unit 20 has a total of 64 electrodes 201 arranged in 8 rows in the x-axis direction and 8 rows in the y-axis direction, with a distance of 10 mm between their centers.

[0023] The electrode section 20 includes a region where a positive electrode 21 is placed and a region where a negative electrode 22 is placed. As shown in the figure, when the electrode section 20 has 64 electrodes 201, 32 electrodes in the range with a large x-coordinate are placed as positive electrodes 21, and 32 electrodes in the range with a small x-coordinate are placed as negative electrodes 22.

[0024] The electrode section 20 may have a central guideline 202 and a horizontal guideline 203. The central guideline 202 is a line displayed vertically (y-direction) between the positive electrode 21 and the negative electrode 22. The horizontal guideline 203 is a line displayed horizontally (x-direction) at the upper ends of the positive electrode 21 and the negative electrode 22 in the y-direction.

[0025] The electrode unit 20 is configured to be attachable to the skin surface of the throat of the human body. Figure 3 shows the electrode unit 20 attached to the throat.

[0026] Figure 3 shows an example of the electrode unit 20 attached to the skin surface of the throat. The electrode unit 20 is attached so as to cover the cricothyroid muscle (CT muscle) in the throat of the human body. In other words, the electrode unit 20 has a positive electrode 21 and a negative electrode 22 and is attached to the skin surface of the throat. The current application unit 160 applies a stimulating current to the electrode unit 20 attached to the skin surface of the throat.

[0027] As described above, the electrode unit 20 may have a central guideline 202 and a horizontal guideline 203. In this case, the electrode unit 20 should be attached with the central guideline 202 aligned with the midline of the throat and the horizontal guideline 203 aligned with the most recessed part of the neck. More specifically, the electrode unit 20 should be attached below the chin and above the clavicle when the subject is viewed from the front, and anterior to the platysma muscle area or anterior to the sternocleidomastoid muscle area when the subject is viewed from the side. In other words, the electrode unit 20 is attached to a position where electrical stimulation can be applied to the intrinsic laryngeal muscles, extrinsic laryngeal muscles, and platysma muscle.

[0028] Next, the configuration and operation flow of the calculation unit 100 of the vibrato control device 10 will be described.

[0029] [Initial setup operation (1) Registration of unpleasant current value] The vibrato control device 10 provides electromyographic stimulation to the throat by outputting a current of a predetermined waveform to the electrode unit 20 attached to the throat. The current that provides electromyographic stimulation to the throat, output from the vibrato control device 10, is also called the stimulation current. For example, the waveform of the stimulation current is a bipolar square wave with a pulse width of 1000 [μm]. The vibrato control device 10 adjusts the speed of the vibrato by adjusting the pulse period of the stimulation current.

[0030] The larger the magnitude of the stimulating current (i.e., the current value), the greater the electromyographic stimulation that can be delivered to the throat. On the other hand, some subjects (hereinafter also referred to as user U) may find a large stimulating current uncomfortable. The magnitude of the stimulating current that user U finds uncomfortable may vary from user U to user U. Furthermore, the magnitude of the stimulating current that user U finds uncomfortable may also change depending on how the electrode unit 20 is attached to the throat. The vibrato control device 10 has a function that allows it to register the magnitude of the stimulating current that user U finds uncomfortable, or each time the electrode unit 20 is attached to the throat. In the following description, registering the magnitude of the stimulating current that user U finds uncomfortable is also called current value calibration. The magnitude of the stimulating current that user U finds uncomfortable is also called the discomfort current value.

[0031] Figure 4 shows an example of the current value calibration operation flow of the vibrato control device 10 of this embodiment. (Step S10) The electrode selection unit 106 of the calculation unit 100 selects an electrode 201 to be used for current value calibration from among a plurality of electrodes 201.

[0032] As preparation for searching for the stimulus position where vibrato is effectively produced, the unpleasant current value is set and vocal exercises are performed. In setting the unpleasant current value, the current value that produces discomfort is determined by gradually increasing the current value for the pair with the furthest distance between electrodes. An example of electrode 201 selection is shown in Figure 5.

[0033] Figure 5 shows an example of the selection result of the electrodes 201 used for current value calibration in this embodiment. The electrode selection unit 106 selects the electrode 201 that outputs a stimulating current from among the positive electrode 21 and the negative electrode 22. In the example shown in the figure, 64 electrodes 201 are arranged in 8 columns in the x-axis direction and 8 rows in the y-axis direction. In the following description, the electrode 201 arranged at coordinates (x1, y1) will be referred to as electrode (x1, y1).

[0034] The electrode selection unit 106 selects four electrodes 201 from among the multiple electrodes 201, namely electrodes (x7,y6), (x7,y7), (x8,y6), and (x8,y7), as the positive electrode 21-1. The electrode selection unit 106 also selects four electrodes 201 from among the multiple electrodes 201, namely electrodes (x1,y2), (x1,y3), (x2,y2), and (x2,y3), as the negative electrode 22-1. In other words, during current value calibration, the electrode selection unit 106 selects the positions of the positive electrode 21 and the negative electrode 22 to be as far apart from each other as possible in the x-axis direction.

[0035] The electrode selection unit 106 selects four electrodes 201 adjacent to each other in the x-axis and y-axis directions, respectively, as either a positive electrode 21 or a negative electrode 22. By selecting multiple (for example, four) electrodes 201 together as either a positive electrode 21 or a negative electrode 22, the contact area of ​​the electrodes 201 with the skin can be increased.

[0036] The unpleasant current values ​​are set for each stimulation frequency, and vocal exercises are performed. To set the unpleasant current values, the current values ​​that cause discomfort are determined for each stimulation frequency in 2 Hz increments from 2 to 20 Hz. In the vocal exercises, a 6 Hz stimulus is applied for 3 seconds, 1 second after vocalization, and this is repeated twice. The current value control unit 102 can be set to an upper limit current value of approximately 6 mA.

[0037] The current value control unit 102 of the calculation unit 100 applies a stimulation current with a current value set by the user U to the electrode unit 20. An example of the current value setting operation screen by the user U is shown in Figure 6.

[0038] Figure 6 shows an example of the discomfort current value registration screen P1 of this embodiment. The discomfort current value registration screen P1 is an operation screen displayed on a display unit 30 connected to the vibrato control device 10, for example. The discomfort current value registration screen P1 includes a stimulation switch P11, a current value adjustment field P12, and a discomfort current value registration field P13. The stimulation switch P11 is an operation image in which the user U selects whether or not to output a stimulation current. The current value adjustment field P12 is an operation image in which the user U sets the current value of the stimulation current. The discomfort current value registration field P13 is an operation image in which the user U registers the current value that causes discomfort. The user U operates the stimulation switch P11 to output a stimulation current from the vibrato control device 10 and sends the stimulation current to their throat via the electrode unit 20. The user U operates the current value adjustment field P12 to gradually increase the current value of the stimulation current. As a result of increasing the stimulation current, the user U operates the registration button in the discomfort current value registration field P13 at the current value that causes discomfort.

[0039] (Step S20) Returning to Figure 4, the stimulus state acquisition unit 101 acquires the stimulus state from user U. Specifically, the operation detection unit 40 detects an operation on the registration button in the discomfort current value registration field P13. The operation detection unit 40 outputs to the stimulus state acquisition unit 101 that the registration button has been operated. If the registration button has been operated, the stimulus state acquisition unit 101 acquires the stimulus state, assuming that the user U has experienced discomfort due to the stimulation current.

[0040] In other words, the stimulation state acquisition unit 101 acquires stimulation state information from the subject to whom the stimulation current is applied, indicating whether or not the stimulation state is within an acceptable range.

[0041] (Step S30) The current value control unit 102 stores the current value of the stimulating current that user U found unpleasant as the unpleasant current value in the determination unit 105. As a result, the unpleasant current value is registered in the storage unit 150 of the vibrato control device 10. The vibrato control device 10 then completes the series of current value calibration processes.

[0042] The operation of the registration button by user U, as described above, can also be said to be information indicating whether or not the stimulation state is within an acceptable range from the subject to whom the stimulating current was applied. In other words, the stimulation state acquisition unit 101 acquires stimulation state information from the subject to whom the stimulating current was applied, indicating whether or not the stimulation state is within an acceptable range. The current application unit 160 controls the current value of the stimulation current variably based on the acquired stimulation state information. Generally, if the current value of the stimulating current is too low, a situation may occur where no vibrato is produced. With the vibrato control device 10 configured in this way, even if the magnitude of the stimulating current that causes discomfort differs for each user U, or each time the electrode unit 20 is attached to the throat, a larger stimulating current can be applied, with the uncomfortable current value as the upper limit.

[0043] [Initial setup operation (2): Selection of electrode combination] The positions of the positive electrode 21 and negative electrode 22 that make it easiest for user U to generate vibrato may vary depending on the positional relationship between the electrode unit 20 attached to the throat and the cricothyroid muscle (CT muscle). The vibrato control device 10 selects which of the multiple electrodes 201 provided by the electrode unit 20 will be used as the positive electrode 21 and the negative electrode 22, that is, it selects a combination of electrodes 201. Selecting a combination of electrodes 201 for each user U, or according to the attachment state of the electrode unit 20, is also called electrode combination search.

[0044] Figure 7 shows an example of the operation flow for electrode combination search in this embodiment. (Step S110) The current value control unit 102 sets an initial current value. The initial current value is a current value smaller than the unpleasant current value registered in the current value calibration. As an example, the initial current value is 50% of the unpleasant current value.

[0045] The electrode selection unit 106 selects a pair of positive electrode 21 and negative electrode 22 of the electrode unit 20. As an example, the 6x8 area of ​​the electrodes 201 placed on the electrode unit 20, excluding the top and bottom rows, is divided into left and right halves, and a 3x2 grid is defined with 2x2 squares as one grid unit. The stimulation positions consist of 27 pairs in total, where the left and right grids each contain a positive electrode 21 and a negative electrode 22, and the rows of electrodes are not adjacent.

[0046] Figure 8 shows an example of a set of positive electrode 21 and negative electrode 22 in this embodiment. In this example, the electrode selection unit 106 selects four electrodes 201 from among a plurality of electrodes 201, namely electrodes (x5,y6), (x5,y7), (x6,y6), and (x6,y7), as the positive electrode 21-2. The electrode selection unit 106 also selects four electrodes 201 from among a plurality of electrodes 201, namely electrodes (x1,y6), (x1,y7), (x2,y6), and (x2,y7), as the negative electrode 22-2.

[0047] In other words, the electrode section 20 has multiple sets of positive electrodes 21 and negative electrodes 22. The electrode selection unit 106 selects a set of positive electrode 21 and negative electrode 22 from among several sets, to which the current application unit 160 applies a stimulating current.

[0048] As described above, it can also be said that at least one of the positive electrode 21 and the negative electrode 22 constituting the electrode section 20 is composed of a plurality of electrodes 201 that are positioned differently from each other. The electrode selection unit 106 selects one or more electrodes 201 that constitute the positive electrode 21 from among a plurality of electrodes 201 that can be used for the positive electrode 21 (for example, the 32 electrodes 201 included in the positive electrode 21 shown in Figure 2). The electrode selection unit 106 also selects one or more electrodes 201 that constitute the negative electrode 22 from among a plurality of electrodes 201 that can be used for the negative electrode 22 (for example, the 32 electrodes 201 included in the negative electrode 22 shown in Figure 2).

[0049] The electrode selection unit 106 selects the position of the positive electrode 21 or negative electrode 22 on the skin surface when the electrode unit 20 is attached to the skin, by selecting an electrode 201 that constitutes the positive electrode 21 or negative electrode 22 from among a plurality of electrodes 201 that are positioned differently from each other. In other words, the electrode selection unit 106 can be said to change the position of the positive electrode 21 or negative electrode 22 on the skin surface by changing the position of the selected electrode 201.

[0050] (Step S120) Returning to Figure 7, the current application unit 160 applies a stimulating current with an initial current value set by the current value control unit 102 to the positive electrode 21-2 and negative electrode 22-2 selected by the electrode selection unit 106.

[0051] (Step S130) The voice acquisition unit 103 acquires information (voice information) of the user U's voice while a stimulating current is applied.

[0052] (Step S140) The determination unit 105 determines whether or not vibrato is being produced by the stimulation current, based on the acquired voice information. More specifically, the determination unit 105 calculates the fundamental frequency F0 of the vibrato by applying a predetermined time-width Hanning window to the acquired voice information and performing a time-frequency transformation (e.g., FFT; Fast Fourier Transform) using a known method. As an example, the predetermined time width is 1 [ms].

[0053] Figure 9 shows an example of the time waveform of the fundamental frequency F0 in vibrato control according to this embodiment. The figure shows the time waveform of the fundamental frequency F0 when the pulse frequency of the stimulation current is 6 Hz.

[0054] Figure 10 shows an example of the amplitude spectrum in vibrato control according to this embodiment. The figure shows the calculation result of the amplitude spectrum when the pulse frequency of the stimulation current is 6 Hz.

[0055] The determination unit 105 calculates a peak frequency F1 in the range of 3-21 Hz from the amplitude spectrum. The determination unit 105 determines that vibrato is being produced by the stimulation current if the difference between the calculated peak frequency F1 and the pulse frequency of the stimulation current (for example, 6 Hz) is within 1 Hz.

[0056] (Step S150) Returning to Figure 7, if the determination unit 105 determines that vibrato is being applied (Step S150; YES), it terminates the search for pairs of positive electrode 21 and negative electrode 22. If the determination unit 105 determines that vibrato is not being applied (Step S150; NO), it proceeds to step S160.

[0057] In this embodiment, the determination unit 105 terminates the search for electrode pairs when it determines that vibrato is present, but this is not the only possible outcome. The determination unit 105 may search all possible electrode pairs and then select the pair that is most likely to produce vibrato. The pair of electrodes most likely to produce vibrato refers to, for example, the pair of electrodes with the largest amplitude at peak frequency F1, the pair of electrodes with the smallest difference between the calculated peak frequency F1 and the pulse frequency of the stimulation current (e.g., 6 Hz), or a combination of these.

[0058] (Step S160) The determination unit 105 determines whether or not it has completed testing all possible combinations of the positive electrode 21 and the negative electrode 22. All possible combinations of the positive electrode 21 and the negative electrode 22 are, for example, the 27 combinations described above.

[0059] If the determination unit 105 determines that the combination has not been completed (step S160; NO), it proceeds to step S170. If the determination unit 105 determines that the combination has been completed (step S160; YES), it proceeds to step S180.

[0060] (Step S170) The electrode selection unit 106 selects another set of electrodes. An example of another set of electrodes is shown in Figure 11.

[0061] Figure 11 shows another example of electrode combinations during the stimulation position setting process in this embodiment. In this example, the electrode selection unit 106 selects four electrodes 201 from among the multiple electrodes 201, namely electrodes (x5, y6), (x5, y7), (x6, y6), and (x6, y7), as the positive electrodes 21-3. In other words, in this example, the electrode selection unit 106 changes the position of the positive electrodes 21-3 by one row in the negative y-axis direction without changing the position of the negative electrode 22-2.

[0062] As described above, the vibrato control device 10 of this embodiment can change the position of the positive electrode 21 in units smaller than the dimensions of the positive electrode 21 (for example, in units of half the dimensions of the positive electrode 21). Similarly, the vibrato control device 10 can also change the position of the negative electrode 22 in units smaller than the dimensions of the negative electrode 22. Therefore, with the vibrato control device 10 of this embodiment, the positions of the positive electrode 21 and the negative electrode 22 can be finely adjusted while the electrode unit 20 remains attached to the skin, and the stimulation position can be set to a position where vibrato is easily generated.

[0063] Returning to Figure 7, the calculation unit 100 repeatedly executes steps S120 to S170. That is, the vibrato control device 10 changes the positions of the positive electrode 21 and the negative electrode 22 one row or one column at a time to search for a set of electrodes that easily produces vibrato. Note that the positions of the positive electrode 21 and the negative electrode 22 when changed one row or one column at a time are the same as the corresponding changes shown in Figures 8 and 11, so they are not shown here.

[0064] In other words, both the positive electrode 21 and the negative electrode 22 are composed of multiple electrodes 201 (small electrodes) that are positioned differently from each other. The electrode selection unit 106 changes the position of the positive electrode 21 and the negative electrode 22 on the skin surface by selecting one of several electrodes 201 that make up the positive electrode 21 from among several electrodes 201 that can be used for the positive electrode 21, and by selecting one of several electrodes 201 that make up the negative electrode 22 from among several electrodes 201 that can be used for the negative electrode 22.

[0065] (Step S180) Once the search for all 27 electrode combinations described above is complete, the current value control unit 102 increases the magnitude of the stimulation current by one step, up to the upper limit of the discomfort current value set in step S30 described above.

[0066] The determination unit 105 compares the amplitude and frequency states at the calculated peak frequency F1 for each electrode set and each stimulation current magnitude of the user U's voice amplitude spectrum. Based on the comparison results, the determination unit 105 selects the stimulation position and stimulation current magnitude that are likely to produce vibrato and stores them in the storage unit 150.

[0067] The current value control unit 102 sets the magnitude of the stimulation current selected by the determination unit 105 as the magnitude of the stimulation current to be applied to user U, and the electrode selection unit 106 stores the state determined by the determination unit in the memory unit 150 based on the stimulation current. In this way, the vibrato control device 10 searches for a stimulation position and magnitude of stimulation current that are likely to produce vibrato, while the electrode unit 20 remains attached to the skin of user U's throat.

[0068] In other words, the voice acquisition unit 103 acquires voice information from the sound acquisition unit 50, which captures the voice generated while a stimulating current is applied. The determination unit 105 determines the state of vibrato in the voice based on the acquired voice information. The electrode selection unit 106 selects a set of electrodes based on the determination results determined by the determination unit 105 for each of the multiple sets.

[0069] [Differentiation] In the example described above, the electrode set was selected based on the state of the user U's voice while a stimulating current was applied, but this is not the only way. For example, the electrode set could be selected based on the state of the user U's throat muscle movement (e.g., acceleration) while a stimulating current was applied.

[0070] In this case, the calculation unit 100 includes an acceleration acquisition unit 104. The acceleration acquisition unit 104 acquires acceleration information from an acceleration detection unit 60, which detects the acceleration of the throat muscles when a voice is produced while a stimulating current is applied. The acceleration detection unit 60 is, for example, an electromyograph sensor that can capture changes in electromyographic potential over time by being attached to the skin. The determination unit 105 determines the state of vibrato in the voice based on the acquired acceleration information. The electrode selection unit 106 selects a set of electrodes based on the determination results determined by the determination unit 105 for each of the multiple sets.

[0071] In the vibrato control device 10 configured in this way, for each user U, the stimulation position that easily produces vibrato and the magnitude of the stimulation current can be set while the electrode unit 20 remains attached to the skin of the user U's throat.

[0072] [Regarding vibrato control] Next, we will explain the process of controlling (vibrato control) that generates vibrato in user U's voice based on the magnitude of the stimulation current and the position of the stimulation electrode, as described above.

[0073] Figure 12 shows an example of the flow of vibrato control processing by the vibrato control system 1 of this embodiment. In this embodiment, we will explain as an example the case in which the state of vibrato (for example, the speed and modulation width of the vibrato) is controlled according to the musical style (for example, rhythm and tempo) of the music, based on music data provided by the music information providing device 70.

[0074] (Step S210) The music information acquisition unit 107 acquires music information from the music information providing device 70. The music information includes, for example, information indicating the pitch, length, intensity, and timbre of the melody of the music. The music information may be music data that can be played on a music player, or it may be data that represents the music using musical notes.

[0075] (Step S220) The generation unit 108 generates vibrato state information based on the acquired song information. Vibrato state information is information that indicates the state of vibrato according to the musical style of the song as indicated by the song information. According to the musical style of the song, for example, if the length of the notes in the melody is relatively long, a deeper vibrato (larger modulation range) will be used, and if the length of the notes is relatively short, a shallower vibrato (smaller modulation range) will be used.

[0076] Figure 13 shows an example of vibrato speed and modulation range. In this figure, the horizontal axis represents time, and the vertical axis represents the fundamental frequency F0 of the vibrato. R is a parameter that indicates the speed of the vibrato, and E is a parameter that indicates the depth (modulation range) of the vibrato. In this example, the average of speeds R1 to R6 indicates the speed of the vibrato, and the average of depths E1 to E6 indicates the depth of the vibrato.

[0077] (Step S230) Returning to Figure 12, the waveform control unit 109 sets the vibrato state indicated by the vibrato state information generated by the generation unit 108 to the desired vibrato state and controls at least one of the frequency and amplitude of the stimulation current.

[0078] In other words, the waveform control unit 109 controls at least one of the frequency and amplitude of the stimulation current based on the desired vibrato state.

[0079] The current application unit 160 outputs a stimulating current to the electrode unit 20 based on the control of the waveform control unit 109. As a result, user U can enjoy singing with vibrato that matches the mood of the song, without having to practice vibrato singing techniques.

[0080] Figure 14 shows an example of experimental results from singing using the vibrato control device 10 of this embodiment. The figure shows an example of the correlation between the frequency of the stimulation current output by the vibrato control device 10 and the frequency of the vibrato sung by user U. As shown in the figure, the frequency of the stimulation current output by the vibrato control device 10 and the frequency of the vibrato sung by user U match well. This demonstrates that the speed of the vibrato sung by user U can be well controlled by using the vibrato control device 10 of this embodiment.

[0081] As described above, the vibrato control system 1 of this embodiment selectively drives the laryngeal muscles by selectively stimulating the user U's neck with a multi-point muscle electrical stimulation system, and controls the speed of the vibrato by changing the stimulation frequency. The vibrato control system 1 makes it possible to control the speed of the vibrato within a frequency range that includes a cognitively appropriate range of vibrato speed (for example, the range of 4 to 14 [Hz] shown in Figure 14).

[0082] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present invention. For example, a computer program to implement the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be loaded into a computer system and executed. The term "computer system" here may include hardware such as an operating system and peripheral devices.

[0083] Furthermore, "computer-readable recording media" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording media" also includes volatile memory (such as DRAM (Dynamic Random Access Memory)) within computer systems that act as servers or clients when programs are transmitted via networks such as the Internet or communication lines such as telephone lines, which retain programs for a certain period of time.

[0084] Furthermore, the above program may be transmitted from a computer system that stores the program in a memory device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" used to transmit the program refers to a medium that has the function of transmitting information, such as a network (communication network) like the Internet or a communication line (communication line) like a telephone line. Furthermore, the above program may be intended to implement some of the functions described above. It may also be a so-called differential file (differential program) that can implement the aforementioned functions in combination with programs already recorded in the computer system. [Explanation of symbols]

[0085] 1...Vibrato control system, 10...Vibrato control device, 100...Calculation unit, 101...Stimulus state acquisition unit, 102...Current value control unit, 103...Voice acquisition unit, 104...Acceleration acquisition unit, 105...Determination unit, 106...Electrode selection unit, 107...Music information acquisition unit, 108...Generation unit, 109...Waveform control unit, 150...Storage unit, 160...Current application unit, 20...Electrode unit, 21...Positive electrode, 22...Negative electrode, 201...Electrode

Claims

1. A current application unit having a positive electrode and a negative electrode, which applies a stimulating current to an electrode unit attached to the skin surface of the throat, A waveform control unit controls at least one of the frequency and amplitude of the stimulation current based on the desired vibrato state, A vibrato control device equipped with [a specific feature].

2. The electrode section has a plurality of sets of positive and negative electrodes. Electrode selection unit that selects from among a plurality of aforementioned sets the set to which the current application unit applies the stimulating current. The vibrato control device according to claim 1, further comprising the following:

3. At least one of the positive electrode and the negative electrode is configured to include a plurality of small electrodes that are positioned differently from each other. The electrode selection unit changes the position of the positive electrode on the skin surface, or / or the position of the negative electrode, by selecting one or more of the small electrodes that constitute the positive electrode from among a plurality of small electrodes that can be used as the positive electrode, and / or by selecting one or more of the small electrodes that constitute the negative electrode from among a plurality of small electrodes that can be used as the negative electrode. The vibrato control device according to claim 2.

4. The electrode selection unit changes the position of at least one of the positive electrode and the negative electrode on the skin surface by selecting a plurality of the small electrodes that constitute the electrode from a plurality of the small electrodes that can be used as electrodes. The vibrato control device according to claim 2.

5. A sound acquisition unit that acquires information about the voice from a sound acquisition unit that collects the voice generated while the aforementioned stimulating current is applied, A determination unit that determines the state of vibrato occurring in the voice based on the acquired voice information, Furthermore, The electrode selection unit selects a set of electrodes based on the determination results determined by the determination unit for each of the multiple sets of electrodes. The vibrato control device according to claim 2 or claim 3.

6. An acceleration detection unit that detects the acceleration of the throat muscles when a voice is produced while the aforementioned stimulating current is applied, and an acceleration acquisition unit that acquires the acceleration information from the acceleration detection unit, A determination unit that determines the state of vibrato occurring in the voice based on the acquired acceleration information, Furthermore, The electrode selection unit selects a set of electrodes based on the determination results determined by the determination unit for each of the multiple sets of electrodes. The vibrato control device according to claim 2 or claim 3.

7. Stimulation state acquisition unit acquires stimulation state information from the subject to whom the aforementioned stimulating current is applied, indicating whether the stimulation state is within an acceptable range. Furthermore, The current application unit controls the current value of the stimulation current in a variable manner based on the acquired stimulation state information. The vibrato control device according to claim 1.

8. The song information acquisition unit acquires song information, A generation unit that generates vibrato state information indicating the vibrato state corresponding to the musical style of the song indicated by the aforementioned song information, Furthermore, The waveform control unit sets the vibrato state indicated by the vibrato state information to the desired vibrato state and controls at least one of the frequency and amplitude of the stimulation current. The vibrato control device according to claim 1.

9. A vibrato control device comprising a current application unit that applies a stimulating current to positive and negative electrodes attached to the throat, and a waveform control unit that controls at least one of the frequency and amplitude of the stimulating current, wherein a computer in the control device that provides control information for the stimulating current, Based on the desired vibrato state, calculate at least one of the frequency and amplitude of the stimulation current, Information indicating at least one of the calculated frequency and amplitude is output to the vibrato control device as control information, A program to execute.

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