Synthesizer detecting pitch and plucking point of stringed instrument to generate tones

Claims

What is claimed is:

1. In an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting device comprising:

pickup means for picking up the acoustic vibration to convert the same into a waveform signal;

first detector means operative according to a fast algorithm for processing the waveform signal so as to responsively produce a first output representative of the pitch of the acoustic vibration;

second detector means operative in parallel to the first detector means for processing the same waveform signal according to a slow algorithm so as to stably produce a second output representative of the pitch of the acoustic vibration; and

selector means for selectively feeding one of the first output and the second output to the tone generator so that the first detector means and the second detector means can cooperate complementarily with each other to ensure responsive and stable detection of the pitch of the acoustic vibration.

2. The pitch detecting device according to claim 1, wherein the first detector means comprises means for calculating a time interval between two peaks successively contained in the waveform signal according to the fast algorithm so as to roughly detect the pitch, while the second detector means comprises means for calculating an average of time intervals among three or more peaks successively contained in the waveform signal according to the slow algorithm so as to finely detect the pitch.

3. The pitch detecting device according to claim 1, wherein the selector means comprises means operative during an initial period immediately after the acoustic vibration is commenced for selecting the first output, and being operative after the initial period has passed for selecting the second output.

4. The pitch detecting device according to claim 1, wherein the selector means comprises means for switching from the first output to the second output when the second detector means succeedingly becomes effective to produce the second output, after the first, detector means precedingly becomes effective to produce the first output.

5. The pitch detecting device according to claim 1, wherein the selector means comprises means operative when the first detector means fails to produce the first output for selecting the second output in place of the missing first output.

6. The pitch detecting device according to claim 1, wherein the first detector means includes a neural network for learning the processing of the waveform signal according to teaching information to improve detection of the pitch, and the selector means includes means operative when the first detector means does not operate well for providing the second output as the teaching information to the first detector means.

7. The pitch detecting device according to claim 1, including variation detector means connected to either of the first detector means and the second detector means for detecting variation of the pitch of the acoustic vibration, quantizer means connected between the selector means and the tone generator and being operative when the detected variation falls within a predetermined range for quantizing the selected one of the first output and the second output to a fixed pitch so as to remove unintentional fluctuation of the acoustic vibration, and controller means operative when the detected variation falls out of the predetermined range for disabling the quantizer means to feed the selected one of the first output and the second output as it is to the tone generator to thereby reserve intentional deviation of the acoustic vibration.

8. The pitch detecting device according to claim 1, including quantizer means connected between the selector means and the tone generator for quantizing the selected one of the first output and the second output to fix the pitch of the musical tone so as to remove fluctuation of the acoustic vibration, and controller means operative during an initial period from the commencing of the acoustic vibration for suppressing the quantizer means to feed the selected one of the first output and the second output as it is to the tone generator so that the musical tone reserves an attack part of the acoustic vibration.

9. The pitch detecting device according to claim 1, wherein either of the first detector means and the second detector means includes means for detecting the pitch of the acoustic vibration commenced by plucking a stringed acoustic instrument at a variable plucking point, and means for detecting the plucking point according to the waveform signal so that a timbre of the musical tone can be controlled according to the detected plucking point.

10. In an electronic musical apparatus having a stringed instrument manually operable at a variable plucking point to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a variable timbre depending on the variable plucking point, a plucking point detecting device comprising:

pickup means for picking up the acoustic vibration to convert the same into a waveform signal which contains a pair of peaks distributed at a variable time interval depending on the plucking point;

detector means for processing the waveform signal to measure the time interval between the pair of the peaks so as to detect the plucking point; and

controller means for controlling the tone generator according to the detected plucking point to change the timbre of the tone generator in response to the plucking point.

11. In an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting device comprising:

pickup means for picking up the acoustic vibration to convert the same into a waveform signal;

detector means for processing the waveform signal to successively detect a pitch of the acoustic vibration;

quantizer means for successively quantizing the detected pitch and feeding the quantized pitch to the tone generator so that the tone generator can generate the musical tone having the successively quantized pitch; and

controller means operative depending on a specific condition of the acoustic vibration for temporarily disabling the quantizer means so as to feed the detected pitch as it is to the tone generator so that the generated musical tone temporarily maintains the detected pitch which reflects the specific condition of the acoustic vibration.

12. The pitch detecting device according to claim 11, wherein the controller means comprises means for detecting variation of the successively detected pitch, and means operative when the detected variation falls within a predetermined range under a normal condition for enabling the quantizer means and being operative when the detected variation falls out of the predetermined range under a specific condition for disabling the quantizer means.

13. The pitch detecting device according to claim 11, wherein the controller means comprises means operative during an initial period from the commencement of the acoustic vibration for disabling the quantizer means, and being operative after the initial period has passed for enabling the quantizer means.

14. In an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting method comprising the steps of:

picking up the acoustic vibration to convert the same into a waveform signal;

operating a first detector according to a fast algorithm for processing the waveform signal so as to responsively produce a first output representative of the pitch of the acoustic vibration;

operating a second detector in parallel to the first detector for processing the same waveform signal according to a slow algorithm so as to stably produce a second output representative of the pitch of the acoustic vibration; and

operating a selector for selectively feeding one of the first output and the second output to the tone generator so that the first detector and the second detector can cooperate complementarily with each other to ensure responsive and stable detection of the pitch of the acoustic vibration.

15. The pitch detecting method according to claim 14, wherein the operating step of the first detector comprises calculating a time interval between two peaks successively contained in the waveform signal according to the fast algorithm so as to roughly detect the pitch, while the operating step of the second detector comprises calculating an average of time intervals among three or more peaks successively contained in the waveform signal according to the slow algorithm so as to finely detect the pitch.

16. The pitch detecting method according to claim 14, wherein the operating step of the selector comprises operating the selector during an initial period immediately after the acoustic vibration is commenced for selecting the first output, and operating the selector after the initial period has passed for selecting the second output.

17. The pitch detecting method according to claim 14, wherein the operating step of the selector comprises switching from the first output to the second output when the second detector succeedingly becomes effective to produce the second output after the first detector precedingly becomes effective to produce the first output.

18. The pitch detecting method according to claim 14, wherein the operating step of the selector comprises operating the selector when the first detector fails to produce the first output for selecting the second output in place of the missing first output.

19. The pitch detecting method according to claim 14, wherein the operating step of the first detector includes operating a neural network within the first detector for learning the processing of the waveform signal according to teaching information to improve detection of the pitch, and the operating step of the selector comprises operating the selector when the first detector does not operate well for providing the second output as the teaching information to the first detector.

20. The pitch detecting method according to claim 14, including steps of operating a variation detector connected to either of the first detector and the second detector for detecting variation of the pitch of the acoustic vibration, operating a quantizer connected between the selector and the tone generator when the detected variation falls within a predetermined range for quantizing the selected one of the first output and the second output to a fixed pitch so as to remove unintentional fluctuation of the acoustic vibration, and operating a controller when the detected variation falls out of the predetermined range for disabling the quantizer to feed the selected one of the first output and the second output as it is to the tone generator to thereby reserve intentional deviation of the acoustic vibration.

21. The pitch detecting method according to claim 14, including steps of operating a quantizer connected between the selector and the tone generator for quantizing the selected one of the first output and the second output to fix the pitch of the musical tone so as to remove fluctuation of the acoustic vibration, and operating a controller during an initial period from the commencing of the acoustic vibration for suppressing the quantizer to feed the selected one of the first output and the second output as it is to the tone generator so that the musical tone reserves an attack part of the acoustic vibration.

22. The pitch detecting method according to claim 14, wherein either of the operating steps of the first detector and the second detector includes detecting the pitch of the acoustic vibration commenced by plucking a stringed acoustic instrument at a variable plucking point, and detecting the plucking point according to the waveform signal so that a timbre of the musical tone can be controlled according to the detected plucking point.

23. In an electronic musical apparatus having a stringed instrument manually operable at a variable plucking point to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a variable timbre depending on the variable plucking point, a plucking point detecting method comprising the steps of:

picking up the acoustic vibration to convert the same into a waveform signal which contains a pair of peaks distributed at a variable time interval depending on the plucking point;

processing the waveform signal to measure the time interval between the pair of the peaks so as to detect the plucking point; and

controlling the tone generator according to the detected plucking point to change the timbre of the tone generator in response to the plucking point.

24. In an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting method comprising the steps of:

picking up the acoustic vibration to convert the same into a waveform signal;

processing the waveform signal to successively detect a pitch of the acoustic vibration;

operating a quantizer for successively quantizing the detected pitch and feeding the quantized pitch to the tone generator so that the tone generator can generate the musical tone having the successively quantized pitch; and

operating a controller dependently on a specific condition of the acoustic vibration for temporarily disabling the quantizer so as to feed the detected pitch as it is to the tone generator so that the generated musical tone temporarily maintains the detected pitch which reflects the specific condition of the acoustic vibration.

25. The pitch detecting method according to claim 24, wherein the operating step of the controller comprises detecting variation of the successively detected pitch, operating the controller when the detected variation falls within a predetermined range under a normal condition for enabling the quantizer, and operating the controller when the detected variation falls out of the predetermined range under a specific condition for disabling the quantizer.

26. The pitch detecting method according to claim 24, wherein the operating step of the controller comprises operating the controller during an initial period from the commencement of the acoustic vibration for disabling the quantizer, and operating the controller after the initial period has passed for enabling the quantizer.

27. A machine-readable media for use in an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, the machine-readable media containing instructions executable by the electronic musical apparatus for causing the electronic musical apparatus to perform a pitch detecting operation including the steps of:

picking up the acoustic vibration to convert the same into a waveform signal;

operating a first detector according to a fast algorithm for processing the waveform signal so as to responsively produce a first output representative of the pitch of the acoustic vibration;

operating a second detector in parallel to the first detector for processing the same waveform signal according to a slow algorithm so as to stably produce a second output representative of the pitch of the acoustic vibration; and

operating a selector for selectively feeding one of the first output and the second output to the tone generator so that the first detector and the second detector can cooperate complementarily with each other to ensure responsive and stable detection of the pitch of the acoustic vibration.

28. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation such that the operating of the first detector comprises calculating a time interval between two peaks successively contained in the waveform signal according to the fast algorithm so as to roughly detect the pitch, while the operating of the second detector comprises calculating an average of time intervals among three or more peaks successively contained in the waveform signal according to the slow algorithm so as to finely detect the pitch.

29. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation such that the operation of the selector comprises operating the selector during an initial period immediately after the acoustic vibration is commenced for selecting the first output, and operating the selector after the initial period has passed for selecting the second output.

30. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation such that the operation of the selector comprises switching from the first output to the second output when the second detector becomes effective to produce the second output after the first detector becomes effective to produce the first output.

31. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation such that the operating of the selector comprises operating the selector when the first detector fails to produce the first output for selecting the second output in place of the missing first output.

32. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation such that the operation of the first detector includes operating a neural network within the first detector for learning the processing of the waveform signal according to teaching information to improve detection of the pitch, and the operating of the selector comprises operating the selector when the first detector does not operate well for providing the second output as the teaching information of the first detector.

33. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation to include operating a variation detector connected to either of the first detector and the second detector for detecting variation of the pitch of the acoustic vibration, operating a quantizer connected between the selector and the tone generator when the detected variation falls within a predetermined range for quantizing the selected one of the first output and the second output to a fixed pitch so as to remove unintentional fluctuation of the acoustic vibration, and operating a controller when the detected variation falls out of the predetermined range for disabling the quantizer to feed the selected one of the first output and the second output as it is to the tone generator to thereby reserve intentional deviation of the acoustic vibration.

34. The machine-readable media according to claim 27, wherein the media contains instructions to control the pitch detecting operation to include operating a quantizer connected between the selector and the tone generator for quantizing the selected one of the first output and the second output to fix the pitch of the musical tone so as to remove fluctuation of the acoustic vibration, and operating a controller during an initial period from the commencing of the acoustic vibration for suppressing the quantizer to feed the selected one of the first output and the second output as it is to the tone generator so that the musical tone reserves an attack part of the acoustic vibration.

35. The machine-readable media according to claim 27 wherein either of the operating steps of the first detector and the second detector includes detecting the pitch of the acoustic vibration commenced by plucking a stringed acoustic instrument at a variable plucking point, and detecting the plucking point according to the waveform signal so that a timbre of the musical tone can be controlled according to the detected plucking point.

36. A machine-readable media for use in an electronic musical apparatus having a stringed instrument manually operable at a variable plucking point to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a variable timbre depending on the variable plucking point, the machine-readable media containing instructions executable by the electronic musical apparatus for causing the electronic musical apparatus to perform a plucking point detecting operation including the steps of:

picking up the acoustic vibration to convert the same into a waveform signal which contains a pair of peaks distributed at a variable time interval depending on the plucking point;

processing the waveform signal to measure the time interval between the pair of the peaks so as to detect the plucking point; and

controlling the tone generator according to the detected plucking point to change the timbre of the tone generator in response to the plucking point.

37. A machine-readable media for use in an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, the machine-readable media containing instructions executable by the electronic musical apparatus for causing the electronic musical apparatus to perform a pitch detecting operation including the steps of:

picking up the acoustic vibration to convert the same into a waveform signal;

processing the waveform signal to successively detect a pitch of the acoustic vibration;

operating a quantizer for successively quantizing the detected pitch and feeding the quantized pitch to the tone generator so that the tone generator can generate the musical tone having the successively quantized pitch; and

operating a controller dependently on a specific condition of the acoustic vibration for temporarily disabling the quantizer so as to feed the detected pitch as it is to the tone generator so that the generated musical tone temporarily maintains the detected pitch which reflects the specific condition of the acoustic vibration.

38. The machine-readable media according to claim 37, wherein the step of operating of the controller comprises detecting variation of the successively detected pitch, operating the controller when the detected variation falls within a predetermined range under a normal condition for enabling the quantizer, and operating the controller when the detected variation falls out of the predetermined range under a specific condition for disabling the quantizer.

39. The machine-readable media according to claim 37, wherein the operating step of the controller comprises operating the controller during an initial period from the commencement of the acoustic vibration for disabling the quantizer, and operating the controller after the initial period has passed for enabling the quantizer.

BACKGROUND OF THE INVENTION

The present invention relates to a pitch detection technology in an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration. The present invention relates also to a plucking point detection technology in an electronic musical apparatus having a stringed instrument manually operable at a variable plucking point to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a variable timbre depending on the variable plucking point.

In the prior art, there is known an electronic musical apparatus called guitar synthesizer or electric guitar, in which a pitch of the guitar is detected in order to drive a tone generator based on the detected pitch so that a tone is synthesized in response to manual performance of the guitar. In the guitar synthesizer, a vibration of a played string is detected by a pickup, and the detected vibration signal is fed to a pitch detector. The pitch detector detects the pitch of the input vibration signal by extracting therefrom a fundamental frequency component.

Generally in a stringed instrument such as the guitar, a timbre of the tone varies in response to a plucking point on the string. However, the conventional guitar synthesizer could not recognize the plucking point, namely a position at which the string is picked. Therefore, the synthesizer could not generate the tone having a timbre corresponding to the plucking point.

Further, the vibration signal from the string contains a lot of harmonics especially in an initial phase just after picking, so that the conventional pitch detector requires plural vibration periods just after the picking in order to extract the fundamental wave component to detect the pitch. Thus, it may cause delay in the actual tone generation.

Further, in the stringed instrument such as the guitar, the player often articulates multiple fingers simultaneously to hold multiple strings. In changing a chord on the instrument, the fingering position is sometimes changed so quickly that the actual fingered position of the string may move off the regular position at the fret. In this situation, the actual length of the string is deviated from the regular length. Thus, the vibration period is unintentionally changed so that the pitch detected by the pitch detector may be shifted as well. In order to compensate for such an erroneous shift, pitch quantization is executed in the prior art, wherein the shifted pitch is corrected to a regular pitch. However, in the stringed instrument such as the guitar, the player sometimes performs a choking method. The choking or bending is one of the playing techniques, in which the string is pushed up or pulled down to change the pitch. In the conventional implementation of the guitar synthesizer, a pitch-bend is imparted to the tone by the choking. However, if the quantization is executed after the pitch detection, the quantization affects the pitch-bend caused by the choking or bending. Thus, the pitch data outputted from the pitch detector changes unnaturally in a stepwise manner.

SUMMARY OF THE INVENTION

Therefore, the first purpose of the present invention is to provide a plucking point detection device and method by which the plucking point of the string is detected in order to control a timbre in response to the plucking point.

The second purpose of the present invention is to provide a pitch detection device and method by which accurate pitch data can be derived at a high speed.

Further, the third purpose of the present invention is to provide a pitch detection device and method by which the accurate pitch can be derived when the player performs unintentional or unconscious pitch-bend, while a natural pitch shift can be ensured when the player intentionally performs the pitch-bend.

According to a first aspect of the invention, in an electronic musical apparatus having a stringed instrument manually operable at a variable plucking point to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a variable timbre depending on the variable plucking point, a plucking point detecting device comprises pickup means for picking up the acoustic vibration to convert the same into a waveform signal which contains a pair of peaks distributed at a variable time interval depending on the plucking point, detector means for processing the waveform signal to measure the time interval between the pair of the peaks so as to detect the plucking point, and controller means for controlling the tone generator according to the detected plucking point to change the timbre of the tone generator in response to the plucking point.

According to a second aspect of the invention, in an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting device comprises pickup means for picking up the acoustic vibration to convert the same into a waveform signal, first detector means operative according to a fast algorithm for processing the waveform signal so as to responsively produce a first output representative of the pitch of the acoustic vibration, second detector means operative in parallel to the first detector means for processing the same waveform signal according to a slow algorithm so as to stably produce a second output representative of the pitch of the acoustic vibration, and selector means for selectively feeding one of the first output and the second output to the tone generator so that the first detector means and the second detector means can cooperate complementarily with each other to ensure responsive and stable detection of the pitch of the acoustic vibration. Preferably, the first detector means comprises means for calculating a time interval between two peaks successively contained in the waveform signal according to the first algorithm so as to roughly detect the pitch, while the second detector means comprises means for calculating an average of time intervals among three or more peaks successively contained in the waveform signal according to the slow algorithm so as to finely detect the pitch.

Preferably, the selector means comprises means operative during an initial period immediately after the acoustic vibration is commenced for selecting the first, output, and being operative after the initial period has passed for selecting the second output. Preferably, the selector means comprises means for switching from the first output to the second output when the second detector means succeedingly becomes effective to produce the second output after the first detector means precedingly becomes effective to produce the first output. Preferably, the selector means comprises means operative when the first detector means fails to produce the first output for selecting the second output in place of the missing first output. Preferably, the first detector means includes a neural network for learning the processing of the waveform signal according to teaching information to improve detection of the pitch, and the selector means includes means operative when the first detector means does not operate well for providing the second output as the teaching information to the first detector means. Preferably, the pitch detecting device includes variation detector means connected to either of the first detector means and the secured detector means for detecting variation of the pitch of the acoustic vibration, quantizer means connected between the selector means and the tone generator and being operative when the detected variation falls within a predetermined range for quantizing the selected one of the first output and the second output to a fixed pitch so as to remove unintentional fluctuation of the acoustic vibration, and controller means operative when the detected variation falls out of the predetermined range for disabling the quantizer means to feed the selected one of the first output and the second output as it is to the tone generator to thereby reserve intentional deviation of the acoustic vibration. Preferably, the pitch detecting device includes quantizer means connected between the selector means and the tone generator for quantizing the selected one of the first output and the second output to fix the pitch of the musical tone so as to remove fluctuation of the acoustic vibration, and controller means operative during an initial period from the commencing of the acoustic vibration for suppressing the quantizer means to feed the selected one of the first output and the second output as it is to the tone generator so that the musical tone reserves an attack part of the acoustic vibration. Preferably, either of the first detector means and the second detector means includes means for detecting the pitch of the acoustic vibration commenced by plucking a stringed acoustic instrument at a variable plucking point, and means for detecting the plucking point according to the waveform signal so that a timbre of the musical tone can be controlled according to the detected plucking point.

According to a third aspect of the invention, in an electronic musical apparatus having an acoustic instrument manually operable to commence an acoustic vibration and a tone generator responsive to the acoustic vibration to generate a musical tone having a pitch corresponding to that of the acoustic vibration, a pitch detecting device comprises pickup means for picking up the acoustic vibration to convert the same into a waveform signal, detector means for processing the waveform signal to successively detect a pitch of the acoustic vibration, quantizer means for successively quantizing the detected pitch and feeding the quantized pitch to the tone generator so that the tone generator can generate the musical tone having the successively quantized pitch, and controller means operative depending on a specific condition of the acoustic vibration for temporarily disabling the quantizer means so as to feed detected pitch as it is to the tone generator so that the generated musical tone temporarily maintains the detected pitch which reflects the specific condition of the acoustic vibration. Preferably, the controller means comprises means for detecting variation of the successively detected pitch, and means operative when the detected variation falls within a predetermined range under a normal condition for enabling the quantizer means and being operative when the detected variation falls out, of the predetermined range under a specific condition for disabling the quantizer means. Preferably, the controller means comprises means operative during an initial period from the commencement of the acoustic vibration for disabling the quantizer means, and being operative after the initial period has passed for enabling the quantizer means.

In operation of the first aspect of the present invention, it is possible to detect the plucking point or playing position where the string is picked by measuring the interval between the peaks or intermittent vibration pulses propagated along the string. In operation of the second aspect of the present, invention, the first pitch detector means detects the pitch of the input waveform signal or vibration signal at high speed, and the second pitch detector means detects the pitch of the input vibration signal according to a pitch detection algorithm different from that of the first pitch detector means. These first and second pitch detector means can cooperate complementarily with each other. Thus the accurate pitch can be detected under variable situations. Further, in operation of the third aspect of the present invention, the quantizer means is controlled to stop the pitch quantization in case that the pitch bending is detected. Thus, if the player performs the string choking or bending, the pitch effected by the bending can be ensured as it is. Moreover, the accurate pitch can be derived even when the fingered position of the string is moved off the regular position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an electric guitar provided with a six-string pickup.

FIG. 2 shows a characteristic curve of a control value in response to a plucking point of the guitar.

FIG. 3 is a schematic block diagram illustrating an arrangement in which a plucking position detection device and a pitch detection device are installed according to the present invention.

FIGS. 4A, 4B and 4C illustrate the principle of the plucking position detection and the pitch detection according to the present invention.

FIG. 5 illustrates vibration pulses propagated along a guitar string on time axis.

FIGS. 6A and 6B show structure of a neural network used in the pitch detection of the first pitch detector, and an actually detected waveform of the pulses transmitted along the string.

FIGS. 7A-7F illustrate a pitch detection algorithm executed by the second pitch detector.

FIGS. 8A and 8B illustrate a zero-cross detection method executed by the second pitch detector.

FIG. 9 is a flowchart illustrating signal processing according to the present invention.

FIG. 10 is a flowchart illustrating the first pitch detection process according to the present invention.

FIG. 11 is a flowchart illustrating the second pitch detection process according to the present invention.

FIG. 12 illustrates a pitch shift derived from the vibration signal detected from the guitar.

FIG. 13 illustrates the pitch shift subjected to quantization process according to the present invention.

FIG. 14 is a flowchart illustrating the conventional quantization process.

FIG. 15 shows a pitch shift in case that the pitch bending is performed.

FIG. 16 shows the pitch shift in case that the pitch bending is performed and the quantization process of the present invention is executed.

FIG. 17 is a flowchart illustrating the quantization process according to the present invention.

FIG. 18 is a flowchart illustrating the pitch bending detection process according to the present invention.

FIG. 19 is a block diagram showing another embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a pitch detection device for detecting a pitch from a vibration waveform, and a plucking point detection device for detecting a plucking point, in a stringed instrument such as guitar. In the description below, the guitar is referred to as an example, and the pitch detection device and the plucking point detection device for the guitar will be explained. In FIG. 1, a guitar 1 is an electric guitar, in which six steel strings are extended between a bridge 4 and a machine head 8. The guitar 1 is provided at three predetermined positions on the guitar body with three pickups 2, by which the vibration of the strings are picked up. The output of the pickups 2 is a composite signal containing vibrations from the six strings. The composite signal is fed out from an output jack 6. Separately from the pickup 2, for transmitting performance information from the gu