JP2508035B2 - Input waveform signal controller - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to an input waveform signal control device in, for example, an electronic guitar.

BACKGROUND OF THE INVENTION Conventionally, a pitch (frequency) is extracted from a waveform signal generated by a performance operation of a natural musical instrument, and a sound source device composed of an electronic circuit is controlled to artificially obtain a sound such as a musical sound. Various types have been developed.

In this type of electronic musical instrument, it is common to extract the pitch of an input waveform signal and then instruct a sound source device to generate a scale tone corresponding to the pitch. By the way, the pitch can be extracted only after the waveform is input for one cycle or more, and there is a problem that the response speed from the sound source device to the start of the generation of the musical tone is deteriorated.

In particular, the lower the tone becomes, the longer the wavelength becomes, so that it takes more time to extract the pitch, and the problem becomes remarkable.

[Object of the Invention] The present invention has been made in view of the above circumstances, and shortens the time from the input of a waveform signal to the actual generation of sound, to improve the response, and to improve the response during playing. It is an object of the present invention to provide an input waveform signal control device that does not give a feeling of naturalness.

That is, according to the present invention, in order to achieve the above-mentioned object, when it is detected that an input waveform signal is given, a sounding instruction is first issued to generate an acoustic signal at a predetermined pitch, and When the pitch of the waveform signal is detected by the pitch extracting means, the point is that a pitch change instruction is given to change the pitch of the acoustic signal to this pitch.

For example, in the case of applying the present invention to an electronic guitar, it is appropriate that the predetermined pitch is the pitch when the fret of the string is not operated, that is, the pitch of the open string, and it is suitable for other musical instruments. However, it is desirable to select the most standard pitch and bass pitch.

That is, when a sound signal is started to be generated at a predetermined pitch before pitch extraction, and the above-mentioned musical sound is changed to that pitch after pitch extraction, it is extremely unclear if the frequency of the first musical sound is perceived by humans. Since it becomes natural, the acoustic signal to be output first should be less than one wavelength (one cycle). Therefore, it is desirable to first output the bass sound signal.

The features of the present invention will be more apparent from the following description of the embodiments.

[Embodiment] An embodiment of the present invention will be described in detail below with reference to the drawings.

Overall Circuit Regeneration FIG. 1 shows the overall circuit configuration of the same embodiment, and this embodiment applies the present invention to an electronic guitar.
The signals at the six input terminals 1 are signals from a pickup provided on each of the six strings stretched on the electronic guitar body and converting the vibration of the strings into an electric signal.

The tone signals from the input terminals 1 ...
Is amplified, the high-frequency component is cut by the low-pass filter (LPF) 3 ... and the basic waveform is extracted, the maximum peak detection circuit (MAX) 4 ..., the minimum peak detection circuit (MIN) 5 ...
... and zero-cross point detection circuit (Zero) 6 ... As shown in FIG. 2, the low pass filter 3 ...
The cutoff frequency is set to 4f, which is four times the vibration sound frequency f of the open string of each string. This is based on the fact that the frequency of the output sound of each string is within two octaves.
The maximum peak detection circuit 4 ... Detects the maximum peak point of the musical tone signal, and the Q output of the flip-flops 14 ... The AND output of the output of ... and the inverted output of the inverter 30 of the zero-cross point detection circuit 6 is given to the CPU 100 as interrupt command signals INTa _{1 to} INTa ₆ via the AND gate 24, and similarly the minimum peak. Also in the detection circuit 5 ..., the minimum peak point of the musical tone signal is detected, and the Q output of the flip-flop 15 ... Connected to the subsequent stage becomes the High level at the rising of the detection pulse signal, and the flip-flop 15 ... aND output between the outputs of the zero-crossing point detecting circuit 6 ... is given to the CPU100 as an interrupt command signal INTb ₁ ~INTb ₆ through the aND gates 25 .....

That is, the maximum peak point is detected and the flip-flop 14
When the waveform crosses from positive to negative while the signal is at the high level, the interrupt command signals INTa _{1 to} INTa ₆ are given to the CPU 100, and conversely the minimum peak point is detected and the flip-flop 15 goes to the high level. when is the interrupt command signal INTb ₁ ~INTb ₆ when the waveform is positively changed from negative CPU100
To enter.

Then, CPU 100 is immediately accepted these interrupt signals, corresponding flip-flop 14 ..., 15 ... a clear signal _{CLa 1 ~CLa 6, CLb 1 ~CLb} 6 occurred to reset. Therefore, no matter how many times the zero-cross point is detected until the next maximum peak point or minimum peak point is detected, the corresponding flip-flops 14..., 15. Become.

Then, in the CPU 100, as will be described in detail later, when an interrupt command signal INTa _{1 to} INTa ₆ or INTb _{1 to} INTb ₆ is given by the vibration output of the string for the first time, the pitch tone corresponding to the vibration of the open string of the string is output. Frequency RO to start
Instruct M8 and tone generator circuit 9.

Then, after that, in the CPU 100, when the interrupt command signals INTa _{1 to} INTa ₆ of the zero-cross point immediately after the detection of the maximum peak point among the interrupt command signals are given, the maximum peak detected in the same manner as before. The difference from the counter value at the zero-cross point immediately after the point is obtained, and the interrupt command signal INTb _{1 to} I at the zero-cross point immediately after the minimum peak point is detected.
When NTb ₆ occurs, the difference from the previously detected counter value is similarly obtained. Both signals INT (INTa ₁ ~ INT
Each time a ₆ and INTb _{1 to} INTb ₆ ) are given, the count value of the counter 7 corresponds to the maximum memory 101 and the minimum memory 1 respectively.
It is stored in 02.

The time count data of the obtained difference in the count values of the counter 7 is sent from the CPU 100 to the frequency ROM 8 and
Frequency data indicating a frequency having one cycle of this count data is read out, sent to the tone generator circuit 9 to generate a tone signal, and sound output from the sound system 10.

Therefore, first, when the musical tone of the pitch corresponding to the open string starts to be generated and the pitch is extracted, the CPU 100 instructs the frequency ROM 8 to change the pitch.

The six tone signals from the low-pass filter 3 ... Are respectively transferred to the A / D converter 1 via the transfer gate T.
It is given to 1, converted into digital data according to the waveform level, and given to the CPU 100. In the CPU 100, when the absolute value of the data indicating the waveform level given from the A / D converter 11 becomes equal to or more than a predetermined constant value, the pronunciation of a musical tone of a predetermined pitch as described above is started, and this data is When the value falls below a certain value, a mute instruction is given to end sound emission. The data showing this waveform level is CP
The sound output level (volume) of the musical sound is controlled by being supplied to the sound source circuit 9 from U100.

The transfer gate T is provided with channel timing signals t _{1 to} t ₆ whose timings are sequentially shifted, respectively.
The sound emission level control of the 6 tone signals (corresponding to the 6 strings) is performed in a time-sharing manner, and in response to this, the frequency ROM 8 and the tone generator circuit 9 form a 6-channel tone generation system by time division processing. There is.

Configuration of Maximum Peak Detecting Circuit 4, Minimum Peak Detecting Circuit 5, and Zero-Cross Point Detecting Circuit 6 FIG. 3 shows a specific configuration of the maximum peak detecting circuit 4, in which the tone signal from the low-pass filter 3 is an operational amplifier 4- It is input to the + terminal of 1, and the output terminal of the operational amplifier 4-1 is connected to the anode side of the diode D1.
The cathode side of D1 is grounded via a capacitor C and a resistor R1 which are connected in parallel, and the operational amplifier 4-1 has a −
Connected to the terminals, the output of the operational amplifier 4-1 is output as the interrupt command signals INTa _{1 to} INTa ₆ for detecting the maximum peak point via the resistor R2 and the amplifier 4-2.

Assuming that the + terminal of the operational amplifier 4-1 is given a waveform as shown in FIG. 4 (a), the capacitor C is charged when the waveform level rises and discharged when the waveform level falls, and FIG. A waveform such as b) is input to the-terminal of operational amplifier 4-1 and the difference value between the + terminal and the-terminal is output only when the waveform level rises. This is the interrupt command signal INTa shown in Fig. 4 (c). Is output as. Interrupt processing is started at the falling point of the pulse signal shown in (c).

Further, the maximum peak detecting circuit may be as shown in FIG. The same parts as those in FIG. 3 are designated by the same reference numerals. That is, there is a diode D2 connected in the opposite direction to the diode D1 in FIG. 3, the operational amplifier 4-3 is connected to the + terminal of the operational amplifier 4-1, and the input signal in is the operational amplifier 4-3. Is supplied to the minus terminal of the resistor through the resistor R4, and the output is fed back to the minus terminal of the resistor through the resistor R3. The operation of the maximum peak detection circuit 4'in FIG. 5 is almost the same as the operation of the minimum peak detection circuit 5 described below, and only the operational amplifier 4-3 for signal inversion is connected to the input side. Omit it.

FIG. 6 shows a specific configuration of the minimum peak detecting circuit 5, and this minimum peak detecting circuit 5 is a maximum peak detecting circuit 4.
However, the direction of the diode D2 is reversed, and the capacitor C repeatedly charges and discharges in the reverse direction as shown in FIG. 4 (d) to generate an interrupt as shown in FIG. 4 (e). The command signal INTb will be obtained.

Further, FIG. 7 shows a specific configuration of the zero-cross point detection circuit 6, in which the tone signal from the low-pass filter 3 is given to the + terminal of the operational amplifier 6-1, and the ground level is connected to the-terminal. The output of operational amplifier 6-1 is resistor R5,
Output via amplifier 6-2. Therefore, when there is a positive level input signal, the amplifier 6-2 outputs High, and when there is a negative level input signal, the amplifier 6-2 outputs Low. That is, the output level is inverted every time the signal passes through the zero cross point.

Operation Next, the operation of this embodiment will be described. Figure 8 shows CPU1
In the main flow of 00, first, after initial setting in step A1, the value of the A / D converter 11 which is the output of the first string is read in step A12, and whether the waveform exceeds a certain level Or, if it is judged at step A13 and it does not reach a certain level, the tone is turned off (steps A14, A1).
Five).

Similarly, processing from the second string to the sixth string (step A2
2 to A25, A32 to A35, A42 to A45, A52 to A55, A62 to A65
(In the figure, the processes other than the processes corresponding to the first and sixth strings are omitted.). If, for example, the first string is operated and a tone signal exceeding a certain level as shown in FIG. 9 (a) is input to the A / D converter 11, step A13
To A16, set the rising flag of the 1st string to 1
And Note that pronunciation is not started yet, so step A1
4. Go through the A15 and process the next string.

Of course, when other strings are operated, steps A23 → A26 →
A24 → A25, A33 → A36 → A34 → A35, A43 → A46 → A44 → A45,
Execute A53 → A56 → A54 → A55, A63 → A66 → A64 → A65.

Then, as described later, the first interrupt command signal INTa
_If either _{one of 1 to} INTa ₆ or INTb _{1 to} INTb ₆ (that is, the waveform rises as shown in FIG. 9A), the interrupt command signal INTa _{1 to} INT is always given to the CPU 100 _first .
is a _6, the (0 peak value is changed in the negative direction) falls reversed until the interrupt command signal INTb ₁ ~INTb is ₆₎ is applied to the CPU100 always initially if the at and above treated Repeat.

Then, the first interrupt command signal INT (INTa _{1 to} IN
When Ta ₆ or INTb _{1 to} INTb ₆ ) is given, an instruction to generate a musical tone corresponding to the frequency of the open string is given from that point, and after that step A13 (A23, A33, A43, A53, A6
3), from step A14 (A24, A34, A44, A54, A64) to step A17 (A27, A37, A47, A57, A67), the pitch is extracted, and then the pitch is extracted in step A17. , Frequency control is performed.

In order to generate the tone of the open string pitch or the extracted true pitch, the CPU 100 sends the control signal to the frequency ROM8.
Give to. And as long as the input waveform signal is above a certain level, steps A12 → A13 → A14 → A17 (same for other strings, A22 → A23 → A24 → A27, A32 → A33 → A34 → A37, A4
2 → A43 → A44 → A47, A52 → A53 → A54 → A57, A62 → A63 → A6
Repeat 4 → A67), and if it falls below a certain level, step A15 (same for other strings, A25, A35, A
45, A55, A65) to start muting.

Now, the operation when the string operation of a certain string is further detailed will be as follows. That is, the musical tone waveform rises by the string operation, the waveform level reaches the first maximum peak point (MAX1 in the figure) shown in FIG. 9 (a), and the maximum peak detection circuit 4 causes the waveform as shown in FIG. 9 (b). A signal is generated, and the flip-flop 14 is set to the high level (see (d) in the figure). Then, when the zero-cross point detection output from the zero-cross point detection circuit 6 is inverted at the zero point of FIG. 9 (a) (see FIG. 9 (c)), the AND gate 24 sends an interrupt command signal INTa (INTa (INTa) to the CPU 100. ₁ ~ INTa ₆ ) is given,
The CPU 100 starts the interrupt processing shown in FIG. First, CPU1
00 resets the flip-flop 14 in step B1, reads the count value of the counter 7, and determines whether or not the waveform is the first wave, that is, whether or not the rising flag is 1 (step B2). The musical tone waveform has just started,
Since this is the first wave, (step A16 (or A26, A3 above)
6, A46, A56, A66)) Proceeding to step B3, tone generation processing for the open string scale (see FIGS. 9 (f) and (g)) is performed, and then the rising flag is set in step B4. Clear,
Further, the process proceeds to step B5, the control flag "1" is set, and the count value of the counter 7 read in step B1 is set in the maximum memory 101. This control flag "1"
Is a flag indicating that the zero-cross point next to the maximum peak point has already been detected. If this flag is cleared, it means that the minimum peak point has been detected. The function of this control flag is as described later.

When a waveform as shown in Fig. 9 (a) is input, each time the zero-cross points Zero2 and Zero3 are continuously detected, the zero-cross point detection circuit 6 outputs an inverted output as shown in Fig. 9 (c). Is obtained.

However, the output of the flip-flop 14 has been reset (in step B1), and no interrupt command signal has been issued.
INTa does not occur. Of course, since the flip-flop 15 is still reset, the interrupt command signal INTb is not generated.

Then, when the minimum peak point indicated by MIN1 in FIG. 9 (a) is reached, a peak detection signal is output from the minimum peak detection circuit 5 and the flip-flop 15 is set.
Then, at the next zero cross point (Zero4), the output of the zero cross point detection circuit 6 is inverted, and as a result, the interrupt command signal INTb is given to the CPU100 from the AND gate 25, and the CPU1
00 starts the interrupt processing shown in FIG. First, the CPU 100 resets the flip-flop 15 in step C1, reads the count value of the counter 7, and determines whether or not the waveform rises (or falls) for the first time, that is, whether or not the rising flag is 1 ( Step C2).

By the way, in this case, since the signal input is started by the rising of the waveform, the above-mentioned step B4
The rising flag is cleared in (see FIG. 10), and the result of judgment in step C2 is NO.

Then proceed to step C6. In this step C6, it is judged whether or not the control flag in the CPU 100 is 1, and this flag is set to the 10th value.
In step B5 of the figure, it is assumed to be 1 in this case, so YE
The determination of S is made and the process proceeds to step C7.

In step C7, it is judged whether or not the scale being currently sounded is that of the open string at the start of sounding as described above, and as is clear from FIGS. 9 (f) and 9 (g), the zero-cross point Ze
When ro4 is detected, the open string scale tone is output, so Y
After determining ES, the process proceeds to step C5. This step C5
Then set the control flag to 0 and this time, the minimum memory
In 102, the count value of the counter 7 read in step C1 is set.

Note that the determination in step C7 is made when the next interrupt command signal INT arrives from the start of generation of the open string scale in the CUP 100 (strictly speaking, when the waveform rises, the interrupt command signal INTa ₁ ~ INTa ₆ , when the waveform falls, the flag that turns on at the next arrival of interrupt command signals INTb _{1 to} INTb ₆ , until the timing of zero cross point Zero5 in the example of Fig. 9) and turns off at other times It can be achieved if provided.

In the case of the input waveform as shown in FIG. 9 (a), when the zero cross point (Zero5) following the maximum peak point shown as MAX2 is reached, the interrupt command signal INTa for detecting the zero cross point immediately after the maximum peak point is given ( FIG. 9 (e)),
The CPU 100 resets the flip-flop 14 in step B1, reads the count value of the counter 7, and
In B2, determine that the waveform is not the first wave, and then step
At B6, it is determined whether the control flag is "0". This control flag becomes "0" at the zero cross point (Zero4) next to the immediately preceding minimum peak point MIN1 (step C5 in FIG. 11).
Then, the CPU 100 proceeds to step B7 to judge NO, and at the next step B8, the maximum peak point MAX1 one cycle before
At the zero cross point (Zero1) immediately after, the time count data set in the maximum time memory 101 is read and subtracted from the current time count data read in step B1 to obtain this result data. As a result, step A17 (or A in FIG. 8 that follows the interrupt processing in FIG. 10 is performed.
27, A37, A47, A57, A67), the above result data is given to the frequency ROM8 and the time length from the zero cross point (Zero1) to the zero cross point (Zreo5) (that is, in FIG. 9 (e))
Control is performed so as to emit a musical sound having a frequency with t ₁ ) as one cycle. In step B5 during the interrupt process,
The CPU 100 sets the control flag "1" and sets the current time count data value in the maximum memory 101.

In this way, the zero crossing point immediately following the maximum peak point is determined in steps C5 and B6, the time (t ₁ ) only for this zero crossing change is measured, and the period calculation is performed in step B8.

Similarly, the zero-cross point (Zero6, Z
ero7) is ignored and the CPU 100 receives the interrupt command signal INTb from the AND gate 25 generated by the detection of the zero-cross point (Zero8) immediately after the minimum value is detected.
After the processing of the flow shown in FIG. 11 is performed, the time interval (t ₂ ) from the previous zero-cross point (Zero4) to the current zero-cross point (Zero8) becomes the pitch extraction data. At this time, the processing is performed in the order of steps C1 → C2 → C6 → C7 → C8 → C5.

Therefore, in this embodiment, first, the musical tone of the open string scale of the relevant string is generated from the first interrupt command signal INT (INTa at the time of rising, INTb at the time of falling), and the maximum is generated after the next same interrupt signal is generated. The time interval between the zero-cross points that occurs immediately after the value detection (t ₁ : Zero ₁ → Zero 5) and the time interval between the zero-cross points that occur immediately after the minimum value detection (t ₂ : that is Zero 4 → ze
ro8) and the frequency change process is performed twice in one cycle. Therefore, a musical tone can be output immediately in response to the generation of an input signal, and if pitch extraction is then performed, the tone scale can be determined according to the pitch to respond to the frequency change of the input signal.

By the way, in the present embodiment, FIG.
Even if the waveform as shown in Fig. 12 is input by the function of the control flag in the flow in Fig. 11, the zero-cross point Zero12,
Zero14 will be ignored.

That is, the zero-cross Zero is used as the interrupt command signal INTa.
Even if the signal corresponding to 12 and Zero14 comes in, the control flag is set to 1 when the zero cross points Zero11 and Zero13 arrive (step B5). Therefore, the judge at step B6 becomes NO, and no cycle calculation is performed. There will be no. In this way, in this embodiment, even if the zero-cross point is continuously detected a plurality of times after the maximum value or the minimum value is detected by this flag, it is ignored, thereby making it possible to further remove the influence of the overtone. There is.

In addition, step A17 (A27, A37, A47, A57, A in FIG. 8)
As the processing in 67), the average value of the previously stored time count data and the time count data obtained this time is taken and output, or if the data difference from the previous time is large, for example, if there is a difference of 20% or more, If the previous one is output, frequency stability can be achieved. Also, the period calculation based on the zero-cross point detection immediately after the maximum peak point, and the period calculation based on the zero-cross point detection immediately after the minimum peak point,
If the starting point of the tone waveform is a rising waveform, after that, the period calculation based on the zero-cross point immediately after the maximum peak point (that is,
Select only t ₁ ), and if the starting point of the tone waveform is a falling waveform, after that, perform periodic calculation based on the zero-cross point immediately after the minimum peak point (that is, calculate only t ₂ ). May be executed.

As described above, in this embodiment, the CPU 1000 can execute an appropriate process as step A17 (A27, A37, A47, A57, A67) shown in FIG. Without changing the external circuit of CPU100
Since it can be done by changing the program, it is more versatile and suitable for intelligentization.

In the above embodiment, both the time interval between the zero cross points immediately after the maximum peak point detection (t ₁ ) and the time interval between the zero cross points immediately after the minimum peak point detection (t ₂ ) are obtained. However, as described above, it is not always necessary to calculate both, and if the circuit configuration is configured with only one, the first
Maximum peak detection circuit 4 and flip-flop 1 shown in the figure
4, one of the set of the ant gate 24 and the inverter 30 or the set of the minimum peak detection circuit 5, the flip-flop 15 and the AND gate 25 is unnecessary and the circuit can be simplified.

In the above embodiment, the CPU 100 processes so as to actually start the generation of the scale tone of the sounded string in step B3 of FIG. 10 or step C3 of FIG. 11, but the completion of these interrupt processes. The tone generation start process may be performed in the series of processes of FIG. 8 which is the main flow afterward.

Further, the period calculation is performed in step B8 of FIG. 10 and step C8 of FIG. 11, and the tone frequency change control based on this period calculation is performed in steps A17, A27, A3 in the main flow of FIG.
7, A47, A57, and A67 are performed, but conversely, this change processing can be performed during each interrupt processing.

In either case, the response to the input signal is better when the tone generation start process and the frequency change process are performed in the interrupt process (FIGS. 10 and 11).

In the above embodiment, as shown in FIG. 9 (g),
By changing the frequency until the first waveform of the open string scale is completed, before the performer feels the periodicity of the output sound at the beginning of the pronunciation (hence the frequency or pitch),
Instead of the actual scale frequency, the pronunciation can be started at an early timing, and the frequency of the sound at the beginning of the pronunciation can be felt to match the human sense.

Therefore, in order to further increase the response speed, when the presence of the string vibration before the maximum value (MAX1) in FIG. 9 (a) is detected, that is, the A / D converter 11 outputs at or above a predetermined level, Processing for detecting a rising flag 1 by the CPU 100 (steps A13A16, A23A26, A33A36, A43A4 in FIG. 8)
6, A53A56, A63A66), the CPU 100 may give a frequency start instruction for the open string scale to the frequency ROM 8 and the tone generator circuit 9.

Furthermore, in the above embodiment, the present invention was applied to an electronic guitar, but the invention is not necessarily limited thereto, and pitch extraction is performed from a voice signal or an electric vibration signal input from a microphone or the like, Any form may be used as long as it is a system that generates an acoustic signal different from the original voice signal at a corresponding pitch or scale frequency. Specifically, the present invention can be similarly applied to those having a keyboard, for example, an electronic piano, an electronic wind instrument, and a stringed instrument, for example, an electronic version of a violin or a koto.

That is, in such various musical instruments, when a musical tone is started to be generated at a predetermined pitch before the pitch is extracted and the musical tone is changed to that pitch after the pitch is extracted, the first musical tone is generated by a human. Is very unnatural, so the musical tone to be output first should be less than one wavelength (one cycle). Therefore, it is desirable to first output the low tone.

In addition, in the above embodiment, the time interval between the zero cross points immediately after the continuous maximum peak points (t ₁ ) or the time between the zero cross points immediately after the continuous minimum peak points is used to detect the pitch of the input waveform signal. Although the interval (t ₂ ) is detected and the obtained time interval is appropriately processed to perform pitch extraction, other than that, for example, a method of extracting the pitch from the time length between simple zero-cross points, the waveform It may be a method of extracting the pitch based on the time length of the point taking the maximum value or the time length of the point taking the minimum value.
A method may be used in which the periodicity is determined by calculating the waveform autocorrelation function and other functions and the pitch is extracted as a result.

Various other pitch extraction methods can be adopted in the present invention.

[Effects of the Invention] As described in detail above, according to the present invention, when it is detected that an input waveform signal is applied, an acoustic signal is first generated at a predetermined pitch, and then pitch extraction is performed. When this is done, the frequency of the acoustic signal is changed to the pitch so that it can be generated, so that the response speed from the input of the waveform signal to the actual generation of the sound can be increased, which is suitable for playing. There are advantages.

[Brief description of drawings]

FIG. 1 is a diagram showing the overall circuit configuration of an embodiment of the present invention,
FIG. 2 is a diagram showing the cutoff frequency of the low-pass filter in FIG. 1, and FIG. 3 is a configuration diagram of the maximum peak detection circuit,
FIG. 4 is a diagram showing operation waveforms of respective parts of the maximum peak detection circuit and the minimum peak detection circuit, FIG. 5 is a circuit configuration diagram showing another example of the maximum peak detection circuit, and FIG. 6 is a diagram showing the minimum peak detection circuit. Configuration diagram, FIG. 7 is a configuration diagram of a zero-cross point detection circuit,
FIG. 8 is a diagram showing a main flow chart of the CPU, FIG. 9 is a time chart diagram showing an input waveform and the operation of each part accompanying it, and FIG. 10 is a diagram showing an interrupt processing flow chart at the time of detecting a zero-cross point immediately after the maximum peak point. FIG. 11 is a diagram showing a flow chart of interrupt processing at the time of detecting a zero-cross point immediately after the minimum peak point, and FIG. 12 is a time chart diagram showing another input waveform and the operation of each part accompanying it. 1 ... Input terminal, 4 ... Maximum peak detection circuit, 5 ... Minimum peak detection circuit, 6 ... Zero-cross point detection circuit, 7 ...
… Counter, 8… Frequency ROM, 9… Sound source circuit, 10…
… Sound system, 14, 15 …… Flip-flop, 10
0 …… CPU, 101 …… Maximum memory, 102 …… Minimum memory.

Claims (2)

(57) [Claims] 1. A pitch extracting means for extracting a pitch of an input waveform signal, an input presence / absence determining means for detecting whether or not the input waveform signal is given, and an input waveform signal existing in the input presence / absence determining means. When the pitch extraction means extracts the pitch of the input waveform signal, the acoustic signal is first generated to generate an acoustic signal having a predetermined pitch, and the acoustic signal is set to the extracted pitch. And an instructing unit for instructing a pitch change so as to change the pitch of the input waveform signal control device. 2. The input waveform signal control device according to claim 1, wherein the predetermined pitch of the acoustic signal for which the instructing means first issues a sounding instruction is a pitch of an open string in a stringed instrument. .