JP5834301B2 - Stringed instrument - Google Patents

Description

The present invention relates to a string musical instrument that can be used to faithfully reproduce the original tone stringed instrument emitted.

  In general, stringed instruments such as ukuleles and acoustic guitars transmit vibrations to the surface plate, which is a resonance plate, through the pieces based on the vibrations of the strings, and further resonate with a resonance body having a sound hole to produce a rich tone. . For this reason, each instrument plays different tones due to differences in the materials that make up instruments such as strings and surface plates, as well as the shape and structure of the resonance drum. However, the volume of these instruments that do not have an electrical amplifying device is not sufficient, and when performing live in a large venue such as a concert hall, collecting and amplifying with a microphone, The volume has been increased. However, collecting musical sounds of stringed instruments with a microphone may sometimes pick up the sounds of other instruments or perform howling. Also, if the microphone position is fixed on the stage, it may not be possible to capture the musical tone of the stringed instrument when the performer performs while moving around on the stage.

  On the other hand, there is a method to increase the volume by attaching a piezo pickup (piezoelectric pickup) to the resonance plate constituting the body (resonance body) of the stringed instrument, converting the string vibration into an electric signal by the piezo pickup, and amplifying the electric signal. Are known. However, the method using a piezo pickup has a problem that the resonance sound due to the drum called boxing cannot be sufficiently picked up, and the output sound is thin and inorganic.

  In order to make it possible to reproduce the resonance sound generated by the stringed instrument body, a technique for adding various effects to an electric signal obtained using a piezo pickup has been proposed (for example, Patent Documents 1 to 3). reference).

JP 2003-15644 A JP 2005-24997 A JP 2009-162997 A

  However, with the techniques disclosed in Patent Documents 1 to 3, the vibration of the string detected by the piezo pickup can be processed into a natural sound to some extent, but the resonance sound of the trunk cannot be faithfully reproduced. Further, in order to detect the vibration of the string using the piezo pickup, the piezo pickup must be attached to the most important part of the stringed instrument, which may adversely affect the original tone of the instrument.

The present invention has been made in view of such circumstances, and an object thereof is to provide a string instrument that can be faithfully reproduced the original tone string instrument emitted.

In order to achieve the above object, a stringed musical instrument according to the first aspect of the present invention includes a hollow body, a sound hole formed in the body, a neck having one end attached to the body, and the neck. a head attached to the end, a string instrument and a string which is stretched between the head and the body, the heel portion of the end portion or the neck side opposite to the neck side an internal body It is provided with a bidirectional microphone that collects musical sounds that resonate inside the body, and the bidirectional microphone is parallel to the surface of the sound hole and perpendicular to the direction in which the sound hole is formed. It has a directivity axis along various directions.

A stringed musical instrument according to a second aspect of the present invention includes, in the first aspect, a gradient filter having a frequency characteristic substantially opposite to the frequency characteristic of the bidirectional microphone, and receives a signal from the bidirectional microphone via the gradient filter. by outputting, further comprising a frequency correction means for flattening the frequency characteristic of the signal output from the bi-directional microphone.

A stringed musical instrument according to a third aspect of the present invention, in the first aspect or the second aspect, detects a howling frequency included in the input signal and a notch filter that attenuates a frequency component centered on the notch frequency with respect to the input signal. Further provided is howling suppression means including howling detection means and control means for setting the howling frequency detected by the howling detection means to the notch frequency of the notch filter.

In the stringed musical instrument according to the fourth aspect of the present invention, in any one of the first to third aspects, the notch filter can be switched between an effective state in which the filter function is enabled and an ineffective state in which the filter function is disabled. .

In the stringed musical instrument according to the fifth aspect of the present invention, the control means enables the notch filter to be in an effective state until a certain time elapses after the howling frequency is detected by the howling detection means, and the notch filter is activated after the certain time has elapsed. Disable state .

  According to the present invention, since the direction in which the sensitivity of the bidirectional microphone becomes the minimum is directed toward the sound hole, it is possible to collect musical sounds that resonate in the internal space of the body without causing howling. The original musical sound emitted by stringed instruments can be faithfully reproduced.

External view showing a configuration example of a stringed musical instrument to which the present invention is applied Top view of the stringed instrument shown in FIG. The perspective view which showed the composition of the microphone unit FIG. 3 is an exploded perspective view of the microphone unit shown in FIG. Diagram showing the directional characteristics of a bi-directional microphone Block diagram showing the configuration of the preamplifier unit The figure which showed the frequency characteristic of the output signal of the bi-directional microphone Diagram showing the frequency characteristics of the gradient filter Diagram showing frequency characteristics of notch filter External view showing another configuration example of stringed instrument Side view of the stringed instrument shown in FIG.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an external view showing a configuration example of a stringed musical instrument to which the present invention is applied. FIG. 2 is a plan view of the stringed instrument shown in FIG.

  As shown in FIGS. 1 and 2, the stringed instrument 10 is made of a stringed instrument (acoustic instrument) such as an ukulele or an acoustic guitar, and has a body (resonant) formed by a front plate 20, a side plate 22, and a back plate 24. A body) 12 and a neck 14 connected to the body 12. A head 16 is provided at the tip of the neck 14 to which a plurality of pegs 26 that can adjust the tension of the string 18 by winding the tip side (starting end) of the string 18 are attached. The front plate 20 constituting the body 12 functions as a resonance plate. A bridge 28 for fixing the rear end of the string 18 is attached to the front plate 20, and the rear end of the string 18 is fixed to a hole or groove (not shown) formed in the bridge 28.

  A fingerboard 32 in which metal fret 30 is embedded at a specific interval is attached to the neck 14. A nut (upper piece) 34 having a plurality of strings 18 arranged at a predetermined interval and provided with a groove for supporting the strings 18 slightly floating above the upper surface of the fret 30 is fixed to the tip of the finger plate 32. Has been. A saddle (lower piece) 35 for fixing the string 18 slightly above the upper surface of the fret 30 and supporting it near the rear end (terminal) of the string 18 is fixed to the bridge 28. Note that some musical instruments may not have the fret 30.

  The string 18 vibrates between the nut 34 and the saddle 35 or between the fret 30 and the saddle 35 on the fingerboard 32. Further, by pressing the string 18 at a predetermined location on the fingerboard 32, the string length between the fret 30 and the saddle 35 is adjusted, and a predetermined pitch (pitch) can be obtained. As a mode for applying vibration to the string 18, there are a mode in which the finger is played at a predetermined position between the finger pressed by the string 18 and the saddle 35, and a mode in which vibration is generated by rubbing with a bow or the like.

  Below each string 18 in front of the bridge 28 of the front plate 20, a sound hole (sound hole) 36 for guiding the sound resonated inside the body 12 to the outside is provided. Reinforcing braces (brikis, sound woods) 38A and 38B are attached to the inner surfaces of the front plate 20 and the back plate 24, respectively. The shape and arrangement of the brace varies depending on the type of musical instrument.

  In the above configuration, when the string 18 is vibrated to perform the stringed instrument 10, the vibration of the string 18 is transmitted to the front plate 20 via the saddle 35 and the bridge 28, thereby causing resonance in the internal space of the body 12. The sound is emitted from the sound hole 36.

  The stringed instrument 10 of the present embodiment includes a microphone unit 40 for collecting sounds that resonate inside the body 12. The microphone unit 40 is detachably attached to the end portion 12a (the end portion on the opposite side of the neck 14 side) of the body 12 at a position away from the sound hole 36 inside the body 12.

  FIG. 3 is a perspective view showing the configuration of the microphone unit 40. FIG. 4 is an exploded perspective view of the microphone unit 40 shown in FIG.

  As shown in FIGS. 3 and 4, a body mounting bolt 50 is provided at the tip of the microphone unit 40. When the microphone unit 40 is attached to the body 12, a positioning nut 52 is screwed from the front end side of the bolt 50, and then a through hole (bolt insertion hole) 54 formed in the end portion 12 a from the inside of the body 12. Insert the bolt 50 into The microphone unit 40 is detachably attached to the body 12 by screwing the fixing nut 60 from the front end side of the bolt 50 via the plain washer 56 and the spring washer 58 and tightening the fixing nut 60 to the positioning nut 52. .

  In the present embodiment, the configuration in which the microphone unit 40 is detachably attached to the body 12 is shown as an example, but is not particularly limited as long as these can be mechanically coupled. It is good also as a structure fixed using friction, without using a nut, and good also as a structure fixed using an adhesive agent.

  As shown in FIG. 3, the microphone unit 40 includes a condenser microphone (hereinafter referred to as a bidirectional microphone) 42 having a bidirectional property and a connector unit 44 that outputs an output signal of the bidirectional microphone 42. The connector portion 44 is disposed outside the body 12 in a state where the microphone unit 40 is attached to the body 12.

  As shown in FIGS. 1 and 2, the preamplifier unit 46 is electrically connected to the connector portion 44 of the microphone unit 40 via a cable (not shown). As a result, the output signal of the bidirectional microphone 42 is input to the preamplifier unit 46 through the connector unit 44.

  The preamplifier unit 46 amplifies the output signal of the bidirectional microphone 42 and outputs a signal subjected to predetermined signal processing. The output signal of the preamplifier unit 46 is input to the external sound loudspeaker 48. The external sound loudspeaker 48 amplifies the input signal, converts it into a sound wave, and outputs it.

  As shown in FIG. 3, the bidirectional microphone 42 is held by a resin microphone holder 64. The bidirectional microphone 42 includes a diaphragm (diaphragm) 62 (illustrated by a broken line in FIG. 3) that vibrates with sound waves, and converts the sound waves into electrical signals and outputs them.

  FIG. 5 is a diagram showing the directivity characteristics of the bidirectional microphone 42. As shown in FIG. 5, the bidirectional microphone 42 has a substantially eight-shaped directivity characteristic. That is, the direction perpendicular to the diaphragm 62 (see FIG. 3) is the directional axis (diaphragm center axis) L, and the sensitivity in the front-rear direction (front and back directions of the diaphragm 62) along the directional axis L is maximized. It has a directivity characteristic in which the sensitivity in the direction perpendicular to (the direction parallel to the diaphragm 62) is minimized (theoretically zero).

  In the present embodiment, the direction in which the sound hole 36 is formed parallel to the opening surface of the sound hole 36 (that is, the front plate 20 of the body 12) (the direction connecting the bidirectional microphone 42 and the center of the sound hole 36). A direction perpendicular to the longitudinal axis X of the stringed instrument 10 in FIG. 5). In other words, the plane including the diaphragm 62 is arranged so as to intersect the sound hole 36 perpendicularly. According to such a configuration, since the sensitivity to the external sound that enters the body 12 from the sound hole 36 that causes the howling is lowered, the howling can be effectively suppressed.

  When the stringed instrument 10 is viewed from above, the center of the sound hole 36 exists in the longitudinal axis direction of the microphone unit 40, and the directional axis L of the bidirectional microphone 42 is perpendicular to the longitudinal axis direction. As described above, the mounting angle of the microphone unit 40 (the rotation angle around the longitudinal axis of the microphone unit 40) is adjusted. The mounting angle of the bidirectional microphone 42 can be easily adjusted by loosening the fixing nut 60.

  FIG. 6 is a block diagram showing the configuration of the preamplifier unit 46. As shown in FIG. 6, the preamplifier unit 46 includes a preamplifier 70, a frequency characteristic correction circuit 72, and a howling suppression circuit 74. The preamplifier 70 amplifies the output signal of the bidirectional microphone 42 and the frequency characteristic correction circuit 72. The signal subjected to the predetermined signal processing by the howling suppression circuit 74 is output to the external sound loudspeaker 48.

  The frequency characteristic correction circuit 72 corrects the frequency characteristic of the output signal of the bidirectional microphone 42 input via the preamplifier 70.

  FIG. 7 is a graph showing the frequency characteristics of the output signal of the bidirectional microphone 42. As shown in FIG. 7, the output signal of the bidirectional microphone 42 has a frequency characteristic in which the amplitude gain increases as the frequency increases. For this reason, if the output signal of the bidirectional microphone 42 is amplified as it is in the preamplifier unit 46 and output to the external sound loudspeaker 48, the timbre of the high frequency band is emphasized and the original timbre of the instrument is impaired.

Therefore, in the present embodiment, a frequency characteristic correction circuit 72 that corrects the frequency characteristic of the output signal of the bidirectional microphone 42 is provided in the subsequent stage of the preamplifier 70. The frequency characteristic correction circuit 72 includes, for example, a gradient filter having the frequency characteristic shown in FIG. This gradient filter has a frequency characteristic in which the amplitude gain gradually decreases as the frequency increases. That is, the frequency characteristic correcting circuit 72, the frequency characteristics of the bi-directional microphones 42 Bei Eteori inclined filter having a frequency characteristic of the generally inverted by outputting a signal through the inclined filter, bidirectional microphone The frequency characteristics of the output signal 42 are flattened. The signal output from the frequency characteristic correction circuit 72 is input to the howling suppression circuit 74.

  As described above, in this embodiment, the frequency characteristic of the microphone is flattened by using a gradient filter having a characteristic opposite to that of the microphone in accordance with the frequency characteristic of the microphone to be used.

  The howling suppression circuit 74 detects a howling frequency included in the input signal, and outputs a signal in which a frequency component including the detected howling frequency is suppressed.

  In the present embodiment, the directivity axis L of the bidirectional microphone 42 is disposed in a direction perpendicular to the direction in which the sound hole 36 is disposed (the direction along the longitudinal axis X of the stringed instrument 10 in FIG. 5). The sensitivity to the sound that reaches the bidirectional microphone 42 from the sound hole 36 can be reduced. However, sound that reaches the bidirectional microphone 42 by repeatedly reflecting inside the body 12 without passing through the surface plate 20 of the stringed instrument 10 or directly reaching the bidirectional microphone 42 from the sound hole 36. Exists. If the sound level is high, howling may not be prevented. In addition, howling may occur when the external environment changes due to the type of musical instrument or the venue.

  Therefore, in the present embodiment, a howling suppression circuit 74 is provided after the frequency characteristic correction circuit 72 in order to more reliably prevent howling due to these factors.

  The howling suppression circuit 74 includes a notch filter 76, a notch control unit 78, and a howling detection unit 80.

  The notch filter 76 is a filter having a frequency characteristic shown in FIG. 9, for example, and attenuates a frequency component having a specific frequency (notch frequency) as a center frequency. The notch filter 76 is configured so that the notch frequency can be varied. The notch frequency is set according to control of a notch control unit 78 described later.

  The howling detection unit 80 takes in an input signal (output signal of the frequency characteristic correction circuit 72) and detects a frequency (howling frequency) at which howling occurs. Specifically, FFT analysis is performed on the input signal at regular time intervals, and when the peak level is above a certain level, the peak frequency is detected and output as a howling frequency. The howling frequency output from the howling detection unit 80 is input to the notch control unit 78.

  The notch control unit 78 controls the notch frequency of the notch filter 76 based on the howling frequency detected by the howling detection unit 80. Specifically, control is performed so that the notch frequency of the notch filter 76 becomes the howling frequency detected by the howling detection unit 80.

  The attenuation amount and notch width of the notch filter 76 (frequency width in the vicinity of attenuation with the notch frequency as the center) can be varied, and these are also set according to the control of the notch control unit 78. For example, the attenuation amount and the notch width of the notch filter 76 may be changed by the notch control unit 78 in accordance with a user operation.

  Further, the notch filter 76 is configured to be able to switch the filter function having the frequency characteristics as shown in FIG. 9 between a valid state (ON state) to be valid and an invalid state (OFF state) to be invalid. Also good. When the notch filter 76 is in an effective state, a frequency component is removed from the input signal with the notch frequency as the center and output. On the other hand, when the notch filter 76 is disabled, the input signal is output as it is. The switching of the notch filter 76 may be changed by the notch control unit 78 in accordance with, for example, a user operation. In addition, the notch filter 76 may be in a valid state until a certain time has elapsed after the howling frequency is detected by the howling detection unit 80, and may be in an invalid state after the certain time has elapsed. In this case, it is possible to suppress deterioration in sound quality while suppressing howling that has occurred abruptly.

  The signal output from the notch filter 76 is output to the external sound loudspeaker 48 as an output of the preamplifier unit 46. The external sound loudspeaker 48 converts the signal output from the preamplifier unit 46 (notch filter 76) into a sound wave and outputs the sound wave. As a result, the musical sound of the stringed instrument 10 collected by the bidirectional microphone 42 is amplified by the external acoustic speaker 48.

  As described above, according to the present embodiment, the directivity axis L of the bidirectional microphone 42 is arranged in a direction parallel to the opening surface of the sound hole 36 and perpendicular to the direction in which the sound hole 36 is formed. Is done. That is, since the direction in which the sensitivity of the bidirectional microphone 42 is minimized is directed toward the sound hole 36, the sensitivity to sound entering the body 12 from the sound hole 36 is reduced, and howling can be effectively suppressed. It becomes possible. Further, since the sensitivity is high in directions other than the direction in which the sound hole 36 is formed, it is possible to capture a wide range of sounds inside the body 12 with a good balance. As a result, the external sound that enters the body 12 from the sound hole 36 that causes howling is canceled, so that it is possible to collect musical sounds that resonate inside the body 12 without causing howling. The original musical sound emitted by can be faithfully reproduced.

  In the present embodiment, the directivity axis L of the bidirectional microphone 42 is arranged in a direction parallel to the opening surface of the sound hole 36 and perpendicular to the direction in which the sound hole 36 is formed. However, the present invention is not limited to this configuration, and if the same effect can be obtained, the directional axis L may be arranged along the above direction and may be slightly shifted.

  In addition, according to the present embodiment, since the preamplifier unit 46 includes the frequency characteristic correction circuit 72, the frequency characteristic of the output signal of the bidirectional microphone 42 can be flattened. Thereby, the effect that it can reproduce faithfully without impairing the original timbre of the musical instrument can be made more remarkable.

  In addition, according to the present embodiment, since the howling suppression circuit 74 is provided in the preamplifier unit 46, howling is suppressed by the howling suppression circuit 74 even when howling occurs due to an external sound reflected inside the body 12. , Howling can be reliably and stably prevented. In particular, in this embodiment, even if the frequency at which howling changes, howling can be suppressed while following the change, so it is effective even when the external environment changes due to the influence of the instrument type or venue. Howling can be suppressed.

  In the present embodiment, the notch filter 76 is preferably configured to be able to switch its filter function between a valid state and an invalid state. If the notch filter 76 is used unnecessarily, the timbre is weakened in the frequency band centered on the notch frequency (that is, the howling frequency) and may be far from the timbre of the original instrument. On the other hand, according to the said structure, the filter function of the notch filter 76 can be made into an effective state or an invalid state according to a user's liking and use condition.

  Moreover, in this embodiment, although the microphone unit 40 showed the structure attached to the end part 12a (end part on the opposite side to the neck 14 side) of the body 12, it is not restricted to this, For example, the inside of the body 12 is shown. You may attach to the heel part 12b (end part by the side of the neck 14). The end portion 12a and the heel portion 12b are places having the highest strength in the structure of the body 12 of the stringed instrument 10, and can stably fix the microphone unit 40. In addition, since the distance between the sound hole 36 and the microphone unit 40 can be secured, the sound collection efficiency of the resonance sound inside the body 12 by the microphone unit 40 can be improved.

  In the present embodiment, the output signal of the bidirectional microphone 42 is led out of the stringed instrument 10 through the connector unit 44 that is configured integrally with the bidirectional microphone 42. (Signal line) is not required, and noise due to unnecessary vibration inside the body 12 can be effectively suppressed.

  The embodiments of the present invention have been described above. However, the present invention is not limited to the above examples, and various improvements and modifications may be made without departing from the scope of the present invention. . Hereinafter, some modified examples will be described.

[Modification 1]
In the embodiment described above, the preamplifier unit 46 is configured separately from the microphone unit 40 and disposed outside the body 12. However, the microphone unit 40 may be configured to include the preamplifier unit 46. In this case, the microphone unit 40 including the preamplifier unit 46 is disposed inside the body 12.

  Needless to say, when the preamplifier unit 46 is configured separately from the microphone unit 40, the preamplifier unit 46 may be disposed inside the body 12.

[Modification 2]
In the above-described embodiment, the application example to the stringed instrument 10 in which the sound hole 36 is provided on the front plate 20 of the body 12 has been described. However, depending on the type of the stringed instrument, for example, as shown in FIG. Some are provided on the side plate 22 instead of the twelve front plates 20. In the stringed musical instrument 10 having such a configuration, as shown in FIG. 11, the directivity axis L of the bidirectional microphone 42 is parallel to the opening surface of the sound hole 36 (that is, the side plate 22 of the body 12) and sound. It is arranged in a direction perpendicular to the direction in which the hole 36 is formed (the direction connecting the bidirectional microphone 42 and the center of the sound hole 36). In other words, the diaphragm (not shown in FIG. 11) of the bidirectional microphone 42 is arranged in parallel with the front plate 20 of the body 12, and the plane including the diaphragm is arranged so as to intersect the sound hole 36 perpendicularly. The As a result, the sensitivity to sound entering the body 12 from the sound hole 36 is reduced, and howling can be effectively suppressed. Therefore, the same effect as the above-described embodiment can be obtained.

[Modification 3]
In the above-described embodiment, the case where the present invention is applied to a stringed instrument in which one sound hole is provided in the resonance body such as an ukulele or an acoustic guitar has been described. For example, it can also be applied to violins and cellos.
(Appendix)
As can be understood from the description of the embodiment described in detail above, the present specification includes disclosure of various technical ideas including the invention described below.
(Appendix 1) A body formed in a hollow shape, a sound hole formed in the body, a neck having one end attached to the body, a head attached to the other end of the neck, the head, and the head A pickup microphone system used for a stringed instrument including a string stretched between bodies, and includes a bidirectional microphone that is disposed inside the body and collects musical sounds that resonate inside the body. The bi-directional microphone is a pickup microphone system having a directivity axis along a direction parallel to a surface where the sound hole is opened and perpendicular to a direction in which the sound hole is formed.
(Supplementary note 2) The pickup microphone system according to supplementary note 1, further comprising frequency correction means for flattening a frequency characteristic of a signal output from the bidirectional microphone.
(Supplementary Note 3) Notch filter for attenuating frequency component centered on notch frequency with respect to input signal, howling detection means for detecting howling frequency included in the input signal, and howling frequency detected by the howling detection means The pickup microphone system according to appendix 1 or 2, further comprising howling suppression means including control means for setting the notch frequency to the notch frequency of the notch filter.
(Appendix 4) A hollow body, a sound hole formed in the body, a neck with one end attached to the body, a head attached to the other end of the neck, the head and the head A pickup microphone system used for a stringed instrument including a string stretched between bodies, and includes a bidirectional microphone that is disposed inside the body and collects musical sounds that resonate inside the body. The bi-directional microphone is a preamplifier unit for a pickup microphone system having a directivity axis along a direction parallel to a surface where the sound hole is opened and perpendicular to the direction in which the sound hole is formed. And a preamplifier unit comprising frequency correction means for flattening frequency characteristics of a signal output from the bidirectional microphone.
(Supplementary Note 5) A body formed in a hollow shape, a sound hole formed in the body, a neck having one end attached to the body, a head attached to the other end of the neck, the head, and the head A pickup microphone system used for a stringed instrument including a string stretched between bodies, and includes a bidirectional microphone that is disposed inside the body and collects musical sounds that resonate inside the body. The bi-directional microphone is a preamplifier unit for a pickup microphone system having a directivity axis along a direction parallel to a surface where the sound hole is opened and perpendicular to the direction in which the sound hole is formed. A notch filter for attenuating a frequency component centered on the notch frequency with respect to the input signal, and a feedback filter included in the input signal. Preamplifier unit comprising: a howling detection unit that detects a grayed frequency, the howling suppressing means and a control means for setting the detected howling frequency by the howling detection unit to notch frequency of the notch filter.
(Appendix 6) A hollow body, a sound hole formed in the body, a neck with one end attached to the body, a head attached to the other end of the neck, the head and the head A pickup microphone system used for a stringed instrument including a string stretched between bodies, and includes a bidirectional microphone that is disposed inside the body and collects musical sounds that resonate inside the body. The bi-directional microphone is a preamplifier unit for a pickup microphone system having a directivity axis along a direction parallel to a surface where the sound hole is opened and perpendicular to the direction in which the sound hole is formed. Frequency correction means for flattening frequency characteristics of the signal output from the bidirectional microphone, and a notch frequency for the input signal. A notch filter for attenuating a frequency component as a heart; a howling detection means for detecting a howling frequency included in the input signal; and a control means for setting the howling frequency detected by the howling detection means to the notch frequency of the notch filter. A preamplifier unit comprising:
(Appendix 7) A hollow body, a sound hole formed in the body, a neck having one end attached to the body, a head attached to the other end of the neck, the head and the head A stringed instrument comprising: a stringed instrument including a string stretched between bodies; and the pickup microphone system according to any one of appendices 1 to 3.

  DESCRIPTION OF SYMBOLS 10 ... String instrument, 12 ... Body, 14 ... Neck, 16 ... Head, 18 ... String, 20 ... Front plate, 36 ... Sound hole, 40 ... Microphone unit, 42 ... Bidirectional microphone, 46 ... Preamplifier unit, 48 ... External Sound loudspeaker 62 ... diaphragm 70 ... preamplifier 72 ... frequency characteristic correction circuit 74 ... howling suppression circuit 76 ... notch filter 78 ... notch control unit 80 ... howling detection unit

Claims (5)

A body formed in a hollow shape, a sound hole formed in the body, a neck having one end attached to the body, a head attached to the other end of the neck, and between the head and the body a string instrument and a stretched a string,
A bi-directional microphone that collects sounds that resonate inside the body, disposed inside the body and disposed at an end portion opposite to the neck side or a heel portion on the neck side ;
The bi-directional microphone is a stringed instrument having a directivity axis along a direction parallel to a surface where the sound hole is opened and perpendicular to a direction in which the sound hole is formed. It has a gradient filter having a frequency characteristic substantially opposite to the frequency characteristic of the bidirectional microphone, and is output from the bidirectional microphone by outputting a signal from the bidirectional microphone via the gradient filter. The stringed instrument according to claim 1, further comprising frequency correction means for flattening frequency characteristics of the signal. A notch filter for attenuating a frequency component centered on a notch frequency with respect to the input signal; howling detection means for detecting a howling frequency included in the input signal; and howling frequency detected by the howling detection means as the notch filter. The stringed instrument according to claim 1, further comprising a howling suppression unit including a control unit that sets the notch frequency.   The notch filter can be switched between an effective state for enabling the filter function and an invalid state for disabling the filter function.
  The stringed instrument according to any one of claims 1 to 3.   The control means sets the notch filter in the valid state until a predetermined time elapses after the howling frequency is detected by the howling detection means, and sets the notch filter in an invalid state after the predetermined time elapses. ,
  The stringed instrument according to claim 4.

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