Patent Publication Number: US-2022230607-A1

Title: Tuning device and tuning method

Description:
TECHNICAL FIELD 
     The present invention relates to a technique of tuning a musical instrument. 
     BACKGROUND ART 
     In the musical instrument field, there is a device that performs tuning on the basis of a musical sound signal output from a musical instrument. For example, Patent Literatures 1 and 2 disclose a device that visually displays to what extent a frequency of sound output from a target musical instrument deviates relative to a frequency of a reference sound. 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] 
     
         
         Japanese Patent Laid-Open No. 2009-86443 
       
    
     [Patent Literature 2] 
     
         
         Japanese Patent Laid-Open No. 2004-53779 
       
    
     SUMMARY 
     Technical Problem 
     According to the invention disclosed in Patent Literatures 1 and 2, a tuning status of an electronic musical instrument can be intuitively understood. On the other hand, in this invention, since a status is reported by using a light emitting element or a liquid crystal screen, an operator needs to always pay attention to the device during tuning work in order to ascertain a hierarchical pitch relationship between a sound output from a musical instrument and a reference sound. That is, there is a problem in that usability is reduced. 
     The present invention has been made in view of this problem, and an objective thereof is to provide a technique for intuitively reporting a difference between a pitch of a sound output from a musical instrument and a pitch of a reference sound. 
     Solution to Problem 
     According to the present invention, there is provided a tuning device including a signal acquisition means for acquiring an audio signal, a comparison means for comparing a frequency of the audio signal with a reference frequency corresponding to the audio signal, and a generation means for generating a first sound signal in a case where the frequency of the audio signal is lower than the reference frequency and generating a second sound signal different from the first sound signal in a case where the frequency of the audio signal is higher than the reference frequency. 
     The tuning device according to the present invention determines a hierarchical relationship between a frequency of an audio signal (for example, a musical sound signal acquired from an electronic musical instrument) and a reference frequency corresponding to the audio signal, and changes a sound signal to be generated on the basis of the hierarchical relationship. 
     According to this configuration, since it is possible to notify an operator of the hierarchical relationship between the frequency of the audio signal and the reference frequency only by sound, it is not necessary to always pay attention to the device, and thus usability can be improved. 
     In the present specification, the frequency of the audio signal is a frequency corresponding to a sound (for example, representing a sound) included in the audio signal, and is a frequency obtained by evaluating the audio signal according to any evaluation method. Therefore, the audio signal does not necessarily have to include only a single frequency component. 
     The first and second sound signals may be sound signals generated in a first cycle, and the first cycle may be a value correlated with a difference between the frequency of the audio signal and the reference frequency. 
     According to this configuration, in addition to a hierarchical relationship between frequencies, it is possible to report by sound how wide a difference between the frequencies is (how much the deviation width is). 
     In a case where the signal acquisition means has detected rising of the audio signal, the generation means may reset counting of the first cycle and immediately start to generate the first sound signal or the second sound signal. 
     For example, in a case where the audio signal is a musical sound signal output from an electronic musical instrument, the first cycle is reset and a sound signal is immediately generated when the operator hits a key or performs picking, and thus it is possible to transfer the current status to an operator more quickly. A rising timing of the audio signal may be, for example, a timing at which a level of the audio signal exceeds a predetermined value. 
     The first and second sound signals may be a combination of two or more sounds having different pitches, and the pitches may have opposite combinations in the first sound signal and the second sound signal. 
     For example, a combination of sounds having different pitches such as “high to low” and “low to high” is provided, and thus it is possible to intuitively report whether the frequency of the audio signal is lower or higher than the reference frequency. 
     Each of the sounds having different pitches does not necessarily have to be a single sound, and may change smoothly. 
     For example, the first and second sound signals may be sweep sounds in which two or more sounds having different pitches are continuously connected to each other, and are preferably exponential chirp signals. In this case, a pitch changes exponentially, and thus it is possible to report a vertical direction in an easy-to-understand manner. 
     In a case where the frequency of the audio signal is substantially the same as the reference frequency, the generation means may generate a third sound signal different from the first and second sound signals. 
     According to this configuration, it is possible to notify an operator by sound that a pitch has reached an ideal state. 
     The tuning device may further include an effect adding means for adding a predetermined effect to the audio signal, and the generation means may mix the audio signal to which an effect has been added with the first sound signal or the second sound signal. 
     The audio signal for reporting a tuning status and the audio signal to which a predetermined effect has been added are mixed, and thus an operator can understand a tuning target sound. 
     According to another aspect of the present invention, there is provided a tuning device including a signal acquisition means for acquiring an audio signal, a comparison means for comparing a frequency of the audio signal with a reference frequency corresponding to the audio signal, and a generation means for generating a sound signal in a first cycle in a case where the frequency of the audio signal is not substantially the same as the reference frequency, in which the first cycle is a value correlated with a difference between the frequency of the audio signal and the reference frequency. 
     As described above, the present invention may also be specified as a device for reporting the magnitude of a frequency deviation width by sound. 
     The signal acquisition means may acquire the audio signal from a musical instrument that is capable of continuously adjusting a pitch according to an amount of tuning operation. 
     The present invention may be specified as a tuning device including at least some of the above means. The present invention may also be specified as a method performed by the tuning device. The present invention may also be specified as a program for executing the method. The above processes or means may be freely combined and implemented as long as there are no technical contradictions therebetween. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a configuration diagram of an electronic musical instrument system according to an embodiment. 
         FIG. 2  is an appearance diagram of a transmitter. 
         FIG. 3  is a hardware configuration diagram of the transmitter. 
         FIG. 4  is a hardware configuration diagram of a sound output device. 
         FIG. 5  is a functional configuration diagram of a DSP (Digital Signal Processor) of a sound output device according to a first embodiment. 
         FIG. 6  is a functional configuration diagram of a determination sound generation unit. 
         FIG. 7  is a flowchart illustrating a process performed by the sound output device. 
         FIG. 8  illustrates an example of a table for specifying a pitch from a frequency. 
         FIG. 9  is a diagram for describing a relationship between a deviation width and a sound emission interval. 
         FIG. 10  is a diagram for describing a relationship between a deviation width and a sound emission interval. 
         FIG. 11  is a functional configuration diagram of a DSP of a sound output device according to a third embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An electronic musical instrument system according to the present embodiment is configured to include a transmitter  10  that wirelessly transmits a sound signal output from an electronic musical instrument and a sound output device  20  that receives and amplifies the wirelessly transmitted sound signal and outputs an amplified result. 
       FIG. 1  is a configuration diagram of the overall electronic musical instrument system according to the present embodiment. 
     The transmitter  10  is a portable device that is connected to a portable electronic musical instrument (an electronic guitar  30  in the present embodiment) having a performance operating device and wirelessly transmits a sound signal output from the electronic musical instrument.  FIG. 2  is a diagram illustrating an appearance of the transmitter  10 . As illustrated, the transmitter  10  may be connected to the electronic musical instrument via a phone plug having a three-pole connection terminal. When the transmitter  10  is inserted into a sound output terminal (phone jack) of the electronic musical instrument, a physical switch (power switch) is turned on, and the transmitter  10  acquires a sound signal from the electronic musical instrument, and wirelessly transmits the sound signal. 
     The electronic guitar  30  has a plurality of strings and a pickup that detects vibrations of the strings, detects the vibrations of the strings with the pickup, converts the vibrations into an electrical signal (sound signal), and outputs the signal. The electronic guitar  30  outputs the sound signal to the transmitter  10  via the phone jack. The output sound signal is modulated and wirelessly transmitted by the transmitter  10  to be received and demodulated by the sound output device  20  that is a headphone device, and is output. 
     With reference to  FIG. 3 , a hardware configuration of the transmitter  10  will be described. 
     The transmitter  10  is configured to include a central processing unit (CPU)  101 , a ROM  102 , a RAM  103 , a connection unit  104 , and a wireless transmission unit  105 . These means are driven by power supplied from a rechargeable type battery (not illustrated). 
     The CPU  101  is a calculation device that manages control performed by the transmitter  10 . 
     The ROM  102  is a rewritable nonvolatile memory. The ROM  102  stores a control program executed by the CPU  101  and data (for example, a frequency used for transmitting a musical sound signal) used by the control program. 
     The RAM  103  is a memory to which the control program executed by the CPU  101  and the data used by the control program are loaded. The program stored in the ROM  102  is loaded to the RAM  103  and executed by the CPU  101  to perform processes described below. 
     The configuration illustrated in  FIG. 3  is only an example, and all or some of the illustrated functions may be executed by using a dedicated circuit. The program may be stored or executed through a combination of a main storage device and an auxiliary storage device other than those illustrated. 
     The connection unit  104  is an interface (for example, a two-pole or three-pole phone plug) for physically connecting the transmitter  10  to the electronic guitar  30 . The connection unit  104  has the connection terminal illustrated in  FIG. 2 , and is configured to be able to acquire a sound signal from the electronic guitar  30  when connected to the electronic guitar  30 . 
     The power switch is disposed near the connection terminal of the connection unit  104 , and the power switch is pressed by inserting the plug. 
     The wireless transmission unit  105  is a wireless communication interface that wirelessly transmits signals. In the present embodiment, the wireless transmission unit  105  transmits a sound signal output from the electronic guitar  30  to the sound output device  20 . 
     The respective means are communicatively connected to each other via a bus. 
     Next, a hardware configuration of the sound output device  20  will be described with reference to  FIG. 4 . 
     The sound output device  20  is a headphone type device that amplifies and outputs a sound signal transmitted wirelessly from the transmitter  10 . The sound output device  20  has (1) a function of performing a predetermined process (such as adding a sound effect) to the received sound signal, amplifying the sound signal, and outputting an amplified result, and (2) a function of tuning an electronic musical instrument on the basis of the received sound signal. 
     The two functions may be switched between by an operation performed by an operator. 
     The sound output device  20  is configured to include a wireless reception unit  201 , a DSP  202 , a ROM  203 , a RAM  204 , an amplifier  205 , and a speaker  206 . These means are driven by power supplied by a rechargeable type battery. 
     The wireless reception unit  201  is a wireless communication interface that receives a signal transmitted from the transmitter  10 . In the present embodiment, the wireless reception unit  201  is wirelessly connected to the wireless transmission unit  105  of the transmitter  10 , and receives a sound signal output from the electronic guitar  30 . 
     The DSP  202  is a microprocessor specialized in digital signal processing. In the present embodiment, the DSP  202  performs processing specialized for processing an audio signal. Specifically, a signal acquired via the wireless reception unit  201  is decoded to acquire a sound signal, and an effect is added to the sound signal as necessary. The sound signal output from the DSP  202  is converted into an analog signal that is then amplified by the amplifier  205 , and then the analog signal is output from the speaker  206 . 
     The DSP  202  is configured to be able to execute a tuning process described in the present specification. A specific process will be described later. 
     The ROM  203  is a rewritable nonvolatile memory. The ROM  203  stores a control program executed by the DSP  202  and data used by the control program. The data stored in the ROM  203  may include, for example, a frequency or a channel list when the sound output device  20  and the transmitter  10  perform wireless communication. The data may also include information required for tuning (for example, information regarding a reference frequency (that will be described later with reference to  FIG. 7 )). 
     The RAM  204  is a memory to which the control program executed by the DSP  202  and the data used by the control program are loaded. The program stored in the ROM  203  is loaded to the RAM  204  and executed by the DSP  202  to perform processes described below. 
     The configuration illustrated in  FIG. 4  is only an example, and all or some of the illustrated functions may be executed by using a dedicated circuit. The program may be stored or executed through a combination of a main storage device and an auxiliary storage device other than illustrated. 
     Next, with reference to  FIG. 5 , a functional block of the DSP  202  will be described. 
     The DSP  202  is configured to include each of functional blocks such as a musical sound signal input unit  2021 , an effector  2022 , a determination sound generation unit  2023 , a function selecting unit  2024 , a volume setting unit  2025 , and a sound emitting unit  2026 . The functional blocks may be realized by the DSP  202  executing corresponding program modules. 
     The musical sound signal input unit  2021  acquires a musical sound signal received via the wireless reception unit  201  and decodes the musical sound signal. The decoded signal is input to the effector  2022  and the determination sound generation unit  2023 . In the following description, a musical sound signal is used to refer to both of an analog signal and a digital signal. 
     The effector  2022  adds an effect to the input musical sound signal. The effector  2022  has a plurality of effect units built thereinto, and may add predetermined effects such as chorus, phaser, tremolo, and vibrato to the musical sound signal. 
     The determination sound generation unit  2023  performs tuning on the basis of the input musical sound signal. Specifically, a frequency (hereinafter, a reference frequency) for comparison is determined on the basis of the input musical sound signal, and a frequency of the musical sound signal is compared with the reference frequency. For example, in a case where it is recognized that the input musical sound signal corresponds to the scale of A4, it is determined that comparison will be performed by using a frequency of 440 Hz, and the two frequencies are compared. On the basis of a result of the comparison, a signal sound (hereinafter, a determination sound) indicating the result of the comparison is generated. In the present embodiment, there are the following three types of determination sounds. 
     (1) A determination sound indicating that the frequency of the musical sound signal is lower than the reference frequency (first determination sound) 
     (2) A determination sound indicating that the frequency of the musical sound signal is higher than the reference frequency (second determination sound) 
     (3) A determination sound indicating that the frequency of the musical sound signal is substantially the same as the reference frequency (third determination sound) 
     The function selecting unit  2024  switches between an active/inactive state of the determination sound generation unit  2023 . The function selecting unit  2024  switches an active/inactive state of the determination sound generation unit  2023  on the basis of an operation performed by an operator by using a switch (not illustrated). 
     Here, in a case where the determination sound generation unit  2023  is brought into an active state, that is, a tuning function is selected to be validated, as described above, a determination sound (any of the first to third determination sounds) is generated by the determination sound generation unit  2023 . The generated determination sound is mixed with a sound signal (hereinafter, an original sound) having passed through the effector  2022  and output. 
     On the other hand, in a case where the determination sound generation unit  2023  is brought into an inactive state, that is, the tuning function is selected to be invalidated, a process using the determination sound generation unit  2023  is not performed. In this case, only a sound signal (original sound) having passed through the effector  2022  is output. 
     The volume setting unit  2025  attenuates the sound signals output from the determination sound generation unit  2023  and the effector  2022  on the basis of the user&#39;s operation. 
     The sound emitting unit  2026  outputs the sound signal output from the effector  2022  and the sound signal output from the determination sound generation unit  2023 . The output sound signals are emitted via the amplifier  205  and the speaker  206 . 
     Next, a process performed by the determination sound generation unit  2023  will be described with reference to  FIGS. 6 and 7 . 
       FIG. 6  is a diagram for describing functional blocks of the determination sound generation unit  2023 .  FIG. 7  is a flowchart illustrating a process performed by the determination sound generation unit  2023  in an active state. 
     First, in step S 11 , it is determined whether or not a musical sound signal has been detected. Here, in a case where a determination result is negative (for example, in a case where a signal level is equal to or less than a predetermined value), the determination sound generation unit  2023  waits for a musical sound signal to be detected. In a case where a determination result is affirmative in step S 11 , the flow proceeds to step S 12 , and a frequency f 1  corresponding to the musical sound signal and a reference frequency fb for comparison are determined. 
     In step S 12 , first, a reference frequency determination portion  32  estimates an original scale of the musical sound signal. For example, the musical sound signal is subjected to Fourier transform to extract frequency components, and the frequency f 1  corresponding to the musical sound signal is specified on the basis of the extracted frequency components. In a case where there are frequency components of a plurality of peaks, a principal frequency may be specified according to a predetermined method. 
     Next, a pitch is estimated on the basis of the specified frequency.  FIG. 8  illustrates an example of data (hereinafter, frequency data) for determining a reference frequency by using a frequency corresponding to a musical sound signal. A pitch closest to the musical sound signal can be estimated by referring to the frequency data as illustrated. 
     The reference frequency fb corresponding to the estimated pitch is determined. For example, in a case where the estimated pitch is A4, 440 Hz is selected as the reference frequency. 
     The frequency data illustrated in  FIG. 8  may be stored in advance in the ROM  203 . 
     In the example in  FIG. 8 , the scale is set to one octave, but the frequency data is not limited to this. For example, in a case where a tuning target is a piano, frequency data in which pitches and frequencies corresponding to 88 strings are associated with each other may be used. In a case where a tuning target is a double bass, frequency data in which pitches and frequencies corresponding to four strings are associated with each other may be used. In a case where a tuning target is a guitar, frequency data in which pitches and frequencies corresponding to six strings are associated with each other may be used. 
     A plurality of pieces of frequency data may be stored. In a case where a plurality of pieces of frequency data are used, the reference frequency determination portion  32  may select frequency data to be used on the basis of an instruction from the operator. A connected musical instrument may be automatically determined, and frequency data to be used may then be selected. 
     Next, a comparison portion  31  compares the frequency of the musical sound signal with the reference frequency, and classifies a comparison result into three patterns such as “lower”, “substantially the same”, and “higher” (step S 13 ). Substantially the same range may be set to a design value, but is preferably set to a range in which tuning is considered to be musically established. 
     In a case where the frequency of the musical sound signal is lower than the reference frequency (or a predetermined range set on the basis of the reference frequency), the flow proceeds to step S 14 A such that the first determination sound is generated and output. In step S 14 A, a selecting portion  33  selects a first determination sound generation portion  34 , and the first determination sound generation portion  34  generates the first determination sound. 
     In a case where the frequency of the musical sound signal is higher than the reference frequency (or a predetermined range set on the basis of the reference frequency), the flow proceeds to step S 14 C such that the second determination sound is generated and output. In step S 14 C, the selecting portion  33  selects a second determination sound generation portion  35 , and the second determination sound generation portion  35  generates the second determination sound. 
     In a case where the frequency of the musical sound signal is substantially the same as the reference frequency (or within a predetermined range set on the basis of the reference frequency), the flow proceeds to step S 14 B such that the third determination sound is generated and output. In step S 14 B, the selecting portion  33  selects a third determination sound generation portion  36 , and the third determination sound generation portion  36  generates the third determination sound. 
     In step S 15 , standby is performed for a predetermined time, and then the flow proceeds to step S 11 . Consequently, a determination sound can be intermittently output. 
     Here, a determination sound will be described. 
     The first determination sound is preferably a sound from which it can be intuitively understood that a frequency of a currently emitted sound is lower than the reference frequency. For example, two types of beep sounds having different pitches in the order of low to high are output, and thus it is possible to transfer to the operator that a pitch is to be raised. 
     The second determination sound is preferably a sound from which it can be intuitively understood that a frequency of a currently emitted sound is higher than the reference frequency. For example, two types of beep sounds having different pitches in the order of high to low are output, and thus it is possible to transfer to the operator that a pitch is to be lowered. 
     (An example of the first determination sound) popi . . . popi . . . popi . . . (po represents a low pitch, and pi represents a high pitch) 
     (An example of the second determination sound) pipo . . . pipo . . . pipo . . . (same) 
     A combination of pitches of the determination sounds is not limited to the examples. 
     The determination sound does not have to be a combination of independent beep sounds. For example, a sound (sweep sound) of which a pitch changes continuously is output, and thus it is possible to transfer a direction in which adjustment is to be performed (whether the pitch is to be adjusted to be raised or lowered). The pitch of the sweep sound changes in proportion to time, but a rate of change is not limited to a linear function. For example, the pitch may change exponentially with time, such as an exponential chirp. According to such a configuration, it is possible to give the operator the impression that the pitch goes up and down linearly. 
     The third determination sound is preferably a sound from which it can be intuitively understood that a frequency of a currently emitted sound is substantially the same as the reference frequency. For example, a beep sound of which a pitch does not change is output, and thus it is possible to transfer to the operator that tuning has been completed. 
     (An example of the third determination sound) pipi . . . pipi . . . pipi . . . . 
     In the above-described example, an emission interval (first cycle) of a determination sound is changed with the predetermined time in step S 15 . 
     As described above, the tuning device according to the present embodiment outputs different determination sounds on the basis of a result of comparing a frequency of a musical sound signal acquired from a musical instrument with the reference frequency. According to such an aspect, it is possible to intuitively understand a direction in which adjustment is to be performed (whether a pitch is to be adjusted to be raised or lowered). 
     Since a musical sound signal that has passed through the effector and a determination sound are mixed and output, it is possible to perform tuning while hearing actually obtained performance sounds. 
     The tuning device according to the present embodiment can be suitably applied to tuning of a musical instrument of which a pitch can be continuously adjusted according to, for example, an amount of operation. For example, when tuning a stringed instrument such as a guitar, a double bass, or a piano, particularly an instrument having pegs for adjusting tension of strings, it is preferable to observe states of the pegs or the strings one by one during work, but in a case where information is given visually as in the related art, an operator cannot concentrate on a state of the instrument. On the other hand, the tuning device according to the present embodiment can report a status only by sound, and thus an operator can concentrate on work. 
     Second Embodiment 
     A second embodiment is an embodiment in which the predetermined time in step S 15  is variable. A hardware configuration of the sound output device  20  according to the second embodiment is the same as that in the first embodiment except processes executed by the determination sound generation unit  2023 . 
     In the second embodiment, the determination sound generation unit  2023  determines the predetermined time in step S 15 , that is, a sound emission interval of a determination sound on the basis of a “deviation width between a frequency of a musical sound signal and the reference frequency”. 
       FIG. 9  is a diagram for describing a sound emission interval of a determination sound. In the present embodiment, in a case where a difference (deviation width) between the frequency of the musical sound signal and the reference frequency is large, control is performed such that a sound emission interval becomes longer. A relationship between the deviation width and the sound emission interval can be defined as illustrated in  FIG. 10 , for example. Such data may be stored in the ROM  203  in advance. 
     According to the second embodiment, an operator can be notified by sound of the magnitude of a difference between a frequency of a musical sound signal and the reference frequency. Consequently, the operator can easily understand a width to be adjusted. 
     In the present embodiment, control is performed such that a sound emission interval becomes longer as a deviation width becomes larger, but the control may be performed such that the sound emission interval becomes shorter as the deviation width becomes larger. That is, the sound emission interval may be correlated with a difference between the frequency of the musical sound signal and the reference frequency. 
     Third Embodiment 
     A third embodiment is an embodiment in which a sound signal indicating a reference frequency is output in addition to a determination sound.  FIG. 11  is a functional block diagram of the sound output device  20  (DSP  202 ) according to the third embodiment. 
     In the third embodiment, the DSP  202  is configured to further include a reference sound generation unit  2027 . The reference sound generation unit  2027  generates a sound signal (hereinafter, a reference sound; for example, a sine wave) corresponding to a reference frequency determined by the determination sound generation unit  2023 . The reference sound is mixed with a determination sound and an original sound to be output via the sound emitting unit  2026 . 
     In the third embodiment, the function selecting unit  2024  is configured such that an active state of the determination sound generation unit  2023  and an active state of the reference sound generation unit  2027  are switched simultaneously or separately. For example, selection may be made such as “only the determination sound generation unit  2023  is in an active state” and “the determination sound generation unit  2023  and the reference sound generation unit  2027  are in an active state”. 
     According to the third embodiment, since an operator can hear an original sound and a reference sound at the same time, it becomes easier to understand a direction in which adjustment is to be performed. 
     Modification Examples 
     The embodiments are only examples, and the present invention may be modified and implemented as appropriate without departing from the spirit thereof. For example, the respective embodiments may be combined and implemented. 
     In the description of the embodiments, the sound output device  20  connected in a wireless manner has been described, but the tuning device according to the present invention may be a device connected in a wired manner. 
     A tuning target does not necessarily have to be an electronic musical instrument, and may be any musical instrument as long as the musical instrument outputs an audio signal. 
     In the description of the embodiments, standby is performed for the predetermined time in step S 15 , but in a case where new rising (attack) of a musical sound signal is detected during the standby, the standby may be interrupted and the determination in step S 13  may be started immediately. A rising timing of the musical sound signal may be, for example, a timing at which a level of the musical sound signal exceeds a predetermined value. 
     According to such a configuration, in a case where an operator hits a key or performs picking, a determination sound is immediately output, and thus a deviation width can be reported more quickly and intuitively. 
     REFERENCE SIGNS LIST 
     
         
         
           
               10  Transmitter 
               20  Sound output device 
               30  Electronic guitar 
               101  CPU 
               102 ,  203  ROM 
               103 ,  204  RAM 
               104  Connection unit 
               105  Wireless transmission unit 
               201  Wireless reception unit 
               202  DSP 
               205  Amplifier 
               206  Speaker