JP2508692B2 - 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, and in particular, stops the extraction of pitch (fundamental frequency) when the input waveform signal falls below a predetermined level. About what you did.

BACKGROUND OF THE INVENTION Conventionally, a pitch (fundamental 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. There have been various developments.

In this type of electronic musical instrument, it is general to extract a pitch and instruct to generate a scale tone corresponding to the pitch regardless of the level of the input waveform signal.

By the way, the input waveform signal oscillates at a small waveform level due to the influence of noise even after the sound is muted.In the past, since pitch extraction is continued even in such a case, unnecessary processing is performed after the sound is muted. In addition, the pitch extraction processing after the muffling causes a delay in the sound generation processing and pitch extraction processing of the next new musical tone that requires immediacy.

[Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to eliminate wasteful processing after the start of mute, and to start the next new tone generation processing and pitch extraction processing. To provide an input waveform signal control device with improved responsiveness.

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention has a frequency measuring means for measuring the frequency of an input waveform signal and a sound generating instruction for generating an acoustic signal according to the frequency measured by the frequency measuring means. An instructing means, a muffling instructing means for instructing to mute the acoustic signal when the level of the input waveform signal becomes equal to or lower than a first predetermined value for a predetermined time, and the level of the input waveform signal for muffling the sound. The main point is to have a measurement stopping means for controlling the frequency measuring means so as not to measure the frequency when the value is smaller than the second predetermined value and smaller than the first predetermined value.

[Operation of the Invention] That is, according to the present invention, by providing the second predetermined value, it is possible to solve the problem that the processing for pitch extraction has conventionally been required even for a noise signal. Further, the second predetermined value is smaller than the first predetermined value, so that the second second value is maintained even after the muffling by the detection of the first predetermined value.
During a certain period until the peak value becomes equal to or less than the predetermined value, the pitch is extracted and the pitch change processing can be performed, so that an important performance effect can be realized.

In addition, once the crest value becomes equal to or lower than the first predetermined value, the level of the waveform signal may momentarily exceed the first predetermined value after the start of the measurement for a predetermined time. Although it is necessary to re-measure the time, if the period until such a mute instruction is issued is extended, and if pitch extraction is always required, the load for the pitch extraction process becomes heavy. In the present invention, that point can also be eliminated.

Hereinafter, an embodiment in which the present invention is applied to an electronic guitar will be described in detail with reference to the drawings.

In the following examples, the maximum peak detector 4 as described below, the minimum peak detection circuit 5, the zero-cross point detection circuit 6, a flip-flop 15, counter 7 to the frequency measuring means, the steps S ₂₅ to S ₂₉ The CPU 100 to execute corresponds to the sounding instructing means, the CPU 100 to execute steps S _{31 to} S _{37 corresponds} to the mute instructing means, and the CPU 100 to execute steps P ₆ and S ₁ corresponds to the measurement stopping means.

Overall Circuit Configuration FIG. 1 shows the overall circuit configuration of this embodiment.
The signal of one input terminal 1 is a signal 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 signal from input terminal 1 ... is the pitch extraction circuit P1.
~ P6 (In the figure, the internal structure is shown only for P1 of the first string.) It is amplified by each internal amplifier 2 ……, and the high-frequency component is cut by the low pass filter (LPF) 3 ……, and the basic waveform Is extracted and maximum peak detection circuit (MAX)
4 ..., minimum peak detection circuit (MIN) 5 ... and zero-cross point detection circuit (Zero) 6 ... The low-pass filter 3 ... is 4 of the vibration sound frequency f of the open string of each string.
The cutoff frequency is set to 4f. this is,
This is based on that the frequency of the output sound of each string is within 2 octaves. The maximum peak detecting circuit 4 detects the maximum peak point of the tone signal, and the flip-flops 14 connected at the subsequent stage at the rise of the detected pulse signal.
The Q output of ... becomes High level, and this flip-flop
The AND output of the output of 14... And the inverted output of the inverter 30 of the zero-crossing point detection circuit 6.
… Via CPU 100 as interrupt command signals INT _{a1 to} INT _a6
Similarly, the minimum peak detection circuit 5 also detects the minimum peak point of the tone signal, and the flip-flop 15 connected to the subsequent stage at the rise of the detected pulse signal.
The Q output of ... becomes High level, and this flip-flop
The output of 15 ... And the output of the zero-cross point detection circuit 6 ... And the AND output are given to the CPU 100 as interrupt command signals INT _{b1 to} INT _b6 via the AND gate 25.

That is, the maximum peak point is detected and the flip-flop 14
When the waveform is crossing from positive to negative when is at High level, the interrupt command signals INT _{a1 to} INT _a6 are given to the CPU100, and conversely the minimum peak point is detected and the flip-flop is detected.
Interrupt command signals INT _{b1 to} INT _b6 are input to the CPU 100 when the waveform changes from negative to positive while 15 is at the high level.

Immediately after the CPU 100 receives these interrupt command signals, the corresponding flip-flops 14 ..., 15 ...
On the other hand, clear signals CL _{a1 to} CL _a6 and CL _{b1 to} CL _b6 are generated and 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, the CPU 100, and an interrupt command signal INT _a1 to INT _a6 or INT _b1 to INT _b6 given by the vibration output of the strings, to generate a chromatic note in accordance with at least one of the time intervals of the respective time interval. At the start of the sound generation, an open string scale sound may be started to be generated, and the frequency may be corrected to a correct frequency after the pitch extraction. The operation at the start of sound generation will be described later.

Then, the above-mentioned time interval is set by the counter 7 as described later.
And the work memory 101. That is, the work memory 101 stores various data such as the count value of the counter 7 at the time of the zero crossing point immediately after the maximum peak point or the minimum peak point.

After the start of sound generation, the frequency of the musical tone being generated is variably controlled according to the time interval data that is sequentially obtained. That is, the CPU 100 sends the data designating the scale to the frequency ROM 8, and as a result, the frequency data showing the corresponding frequency is read and sent to the tone generator circuit 9 to generate a musical tone signal, which is emitted from the sound system 10. It

The tone signals from the low pass filters 3 ... Are given to the A / D converters 11 ... And converted into digital data corresponding to the waveform level.

And the output of this A / D converter 11 ... Latch 12
... is latched on. The latch signal for the latch 12 ... is the signal of which the output of the flip-flop 14 ... or the output of the flip-flop 15 ... Is given through the OR gates 16. The clock signal CL given via 17 ... Is used to store data indicating the maximum and minimum peak values of the waveform or the level of the input waveform signal at each time. The AND gate 26 ... Is opened by the latch instruction signals L1 to L6 from the CPU 100, and the latch instruction signal L1
~ L6 is the interrupt command signal IN when the above zero cross point is passed
When T _{a1 to} INT _a6 is given, it becomes a high level, and when passing through the maximum peak point or the minimum peak point, the peak time signals P _{1 to} P ₆ from the flip-flops 14 ... It goes low. Therefore, Andgate 24 ……, Andgate 25…
Interrupt command signals INT _{a1 to} INT _a6 , INT _{b1 to} INT via
_{In the} period when _b6 is given, in the case of a waveform input such as a sine wave, the peak value at each time is latched from the first half of the peaks and valleys of the waveform, that is, the zero cross point to the maximum peak point or the minimum peak point, and the maximum peak value is latched. From the point or the minimum peak point to the next zero cross point, the peak value of the waveform is held.

Then, the output of the latch 12 ... Is given to the CPU 100, and sound generation start, sound generation stop, pitch extraction start, pitch extraction stop, and control of the output sound emission level (volume) are performed according to this data. The peak value, which is the peak value stored in the latch 12 ... Before the output of the latch instruction signals L1 to L6 is stopped, is sequentially written in the work memory 101.

That is, in the CPU 100, when the absolute value of the data indicating the waveform level given by the A / D converter 11 ... becomes equal to or higher than a predetermined constant value, the tone generation is started and the pitch (fundamental frequency) is extracted. When the data becomes less than the mute level value OFFLEV shown in FIG. 7, the volume level is rapidly attenuated to instruct the end of the sound emission. When the stop level value falls below PITLEV, the pitch (fundamental frequency) extraction is also terminated. The details of the operation are as described later.

In FIG. 1, the A / D converter 11 is provided independently of each of the pitch extraction circuits P1 to P6, but one A / D converter is provided.
Of course, it is also possible to use the D converter in a time division manner.

The frequency ROM 8 and the tone generator circuit 9 form a tone generation system of at least 6 channels by time division processing.

Note that FIG. 2 shows a time chart of the signal waveform of each part in the pitch extraction circuit P1, in which the output of the low-pal filter 3 is, the output of the maximum peak detection circuit 4 is, and the output of the minimum peak detection circuit is shown. 5 is the output of the zero-cross point detection circuit 6, is the interrupt command signal INT _{a1 to} INT
_a6, the interrupt command signal INT _b1 ~INT _b6, is latch instruction signal L ₁ ~L _6.

Operation Next, the operation of this embodiment will be described. Figure 3 shows CPU1
FIG. 4 is a flow of an interrupt routine of 00, and FIG. 4 is a main flow. Although FIG. 3 and FIG. 4 only show the processing for one string, the processing for all strings is exactly the same, so if the CPU 100 executes the processing for each string in a time-division manner. good.

Registers in Work Memory 101 Now, before describing specific operations of the CPU 100, main registers in the work memory 101 will be described.

The STEP register takes four stages of 0, 1, 2, and 3, and as string vibration is made (see FIG. 5 (a) or FIG. 6 (a)), FIG. 5 (b) or FIG. The contents change as shown in (b). When this STEP register is 0, it indicates a note-off (silence) state.

The SIGN register indicates whether the zero-cross point for period measurement is the next zero-cross point after the maximum peak (MAX) point or the next zero-cross point after the minimum peak (MIN) point. When is the latter.

The REVERSE register is a register that stores data that checks whether or not interrupt processing has been performed due to the arrival of the zero-cross point after the peak point on the side opposite to the zero-cross point represented by the SIGN register has elapsed. Used to check pitch (fundamental frequency) extraction control.

The T register stores the value of the counter 7 at a specific point for measuring the cycle of the input waveform. The counter 7 is performing a free running operation of counting with a predetermined clock.

The AMP (i) register is latched from the A / D converter 11 to the latch 12
A register for storing the maximum or minimum peak value (actually, an absolute value) latched by the AMP (1) is for the maximum peak, and AMP (2) is for the minimum peak.

Data representing the measured period is input to the PERIOD register, and the CPU 100 controls the frequency of the frequency ROM 8 and the tone generator circuit 9 based on the contents of this register.

The OF register is a register which becomes "1" when the level data of the input waveform latched by the latch 12 becomes equal to or lower than the mute level value OFFLEV shown in FIG. 7, and becomes "0" when it is equal to or higher than the OFFLEV being sounded. .

The OFT register is a register in which the count value of the counter 7 is set when "1" is set in the OF register. Based on this count value, the time when the value of the OF register is "1" is set. The mute (note-off) processing is executed when a predetermined time, for example, the time of the open string cycle of the contact string, more specifically, the sixth string for 12 milliseconds or more.

Further, as will be described later, in this embodiment, for various judgments,
Three constants (threshold levels) are set in the CPU100.

The first one is ONLEFI, which is shown in FIG.
As shown in Figure (a), note-off is now in progress,
When a peak value larger than this ONLEVI value is detected, the CPU 100 starts the operation for period measurement, assuming that the string has been picked.

ONLEVII is in the note-on state (while sounding), and if the difference between the previous detection level and the current detection level is more than this value, it is determined that there was an operation by the tremolo playing method, etc.
This is for performing the pronunciation start (relative on) process again.

As shown in FIG. 7 (a), OFFLEV is in a note-on state (while sounding), and a waveform level value below this value is detected for a predetermined time (for example, one cycle time of open string pitch). And note-off (silence) processing.

PITLEV is OFFLEV as shown in Fig. 7 (a).
If the peak value of the input waveform is set to a value one step smaller than this value and the peak value is less than this value, the pitch (fundamental frequency) extraction processing is not performed.

From the above description, it will be easy to understand the operation of the interrupt routine and the main routine described below.

Interrupt processing Well at the zero-crossing point, the interrupt command signal INT _a, which is the output of the AND gate 24 or AND gate 25, the advent of the CPU100 of INT _b, performs interrupt processing of FIG. 3.

That is, the interrupt command signal INT _a On input, first the process in step P _1, the a register in the CPU100 to 1,
At the time of inputting the interrupt command signal INT _b , first, the step P ₂
2 is set in the a register by the processing of.

Then, at step P ₃ , the value of the counter 7 is preset in the t register in the CPU 100. In the subsequent step P ₄ , the level data of the input waveform is read from the latch 1 and set in the b register in the CPU 100.

In this case, interrupt command signals INT _{a1 to} INT _a6 , INT _{b1 to} I
NT _b6 is given at the arrival of the zero-cross point immediately after passing through the maximum peak point and the minimum peak point, and until this zero-cross point is passed, the latch 12 has the maximum peak point or the minimum peak point immediately before it. Since the peak level data is held, the peak level data of the input waveform is set in the b register.

Then, in step P ₅ , the flip-flop 14
Or clear flip-flop 15.

In the following step P ₆ , it is determined whether or not the peak level data of the b register has become equal to or less than the pitch extraction stop level value PITLEV.
_{At 7} , the contents of the above a, b and t registers are stored in the work memory 1
Transfer to 01 and store, and interrupt processing ends.

Thus, every time the zero cross point is passed, data (a register) indicating whether the zero cross point is after the maximum peak point has passed or after the minimum peak point has passed, the maximum peak point or the minimum peak point, Peak level data (b
Register), and the count data (t register) of the counter 7 at this zero-cross point for measuring the cycle (pitch) of the input waveform is set.

If, in the above Step P _6, if the peak level data has become less pitch extraction stop level value PITELEV, for the new data in step P ₇ become process of setting the work memory 101 is performed, which will be described later main routine in step S ₁ is judged as NO in step S ₃₀ to S ₃₈
Only mute processing is executed, the pitch extraction process of step S ₂₆ to S ₂₉ is not performed.

In this way, it is possible to prevent unnecessary pitch extraction processing from being performed after the tone is muted.

Main Processing In the main routine (FIG. 4), in step S ₁ ,
By the interrupt processing as described above, the work memory 101
The contents of a ', b', and t '(the same as a, b, and t are shown as a', b ', and t'because they were recorded previously).
Is judged whether or not it has been written, and if no interrupt processing has been carried out, a NO judgment is made, and this step S ₁ is executed through the mute processing flow of steps S _{30 to} S ₃₈ described later. Execute repeatedly.

Then, if YES is determined in the step S ₁ , the process proceeds to the next step S ₂ and the contents a ', b', t'are read out. Next, in step S ₃ , the peak value of the peak point of the same type (that is, maximum or minimum) stored in the AMP (a ′) register is read into the c register in the CPU 100, and the peak value b ′ extracted this time is read. Set in the AMP (a ') register.

Now, next step S ₄ to S _6, the contents of the STEP register is judge whether each 3,2,1. Now, if it is the first state, since the STEP register is 0, it is judged NO in steps S ₄ , S ₅ , and S ₆ . Then, in step S ₇ , the peak value b ′ detected this time is next.
Judge whether is larger than ONLEVI.

If the peak value b'is smaller than ONLEVI, the tone generation start process is not performed yet, and the process returns to step S ₁ .
If, FIG. 5 (a), when a large input from ONLEVI as FIG. 6 (a) is obtained, the determination in step S ₇ is Y
It becomes ES, and proceeds to step S ₈ .

Then, in step S ₈ , 1 is set in the STEP register,
Next, in step S ₉ , 0 is set in the REVERSE register, and in step S ₁₀ , the value of a ′ (that is, 1 at the zero-cross point immediately after the maximum peak point and 2 at the zero-cross point immediately after the minimum peak point) is set. Input to SIGN register.

Then, in step S ₁₁ , the value of t ′ is set in the T register. As a result, the contents of a'are stored in the SIGN register (FIG. 5 (a), SIGN is 1 in the case of FIG. 6 (a)), b'is stored in the AMP register, and t'is stored. It has been set in the T register. Then, the process returns to step S ₁ .

By the above description, the processing of the main routine immediately after the zero cross point Zero1 in FIGS. 5 (a) and 6 (a) is completed.

Now, the process in the main routine immediately after the zero-cross point Zero2 will be described. In that case, the above step S ₁
→ S ₂ → S ₃ → S ₄ → S ₅ → S ₆ The data set process and the sounding stage discrimination process are executed, and YES is determined in this step S ₆ , and then the process proceeds to step S ₁₂ .

When the waveform changes in the positive direction at the time of input as shown in FIGS. 5 (a) and 6 (a), the SIGN register is 1, and since the peak in the negative direction has passed this time, a ' Since the register is 2, judge NO. If the zero-cross point is reached immediately after the peak value of the same polarity, this step S
_If YES is determined in step ₁₂ and no operation is continuously performed, step S ₁
Go back.

Well, now snow to step S ₁₃ is the judge of step S ₁₂ in NO, the STEP register and 2. (See FIG. 5 (b) and FIG. 6 (b)).

Then, step S ₁₄ is executed after step S ₁₃ ,
Compare the previous peak value (AMP (SIGN)) with the current peak value (b '). Now, as shown in FIG. 5A, if the previous value x ₀ is smaller than the current value (x ₁ > x ₀ ), the determination result is YES, and the current time t ′ should be set as the measurement start point of the cycle ( Fifth
(See FIG. 6C) Steps S ₁₄ to S ₁₀ and S ₁₁ are executed to set the SIGN register to 2 and transfer the contents of the t ′ register to the T register.

REVERS Conversely, larger the previous peak value than current peak value, i.e. if x ₁ <x ₀ as FIG. 6 (a), in step S ₁₅ the judgment NO at Step S ₁₄
Set the E register to 1. The SIGN register retains the previous value of 1. Therefore, in this case, the preceding zero cross point (Zero1) is the start point of the cycle measurement (see FIG. 6 (c)).

Then, after passing through the next zero cross point (Zero3), first when performing the main flow, YES in step S ₅
Is judged and the process proceeds to step S ₁₆ . This time a'is 1
And SIGN is 2 in the case of FIG. 5 and SI in the case of FIG.
Since GN is 1, in the case of FIG. 5, step S ₁₆
And NO judgment was done. Return to step S ₁₅ and return to step S ₁ . That is, the CPU 100 recognizes that the first peak (amplitude x ₂ ) has passed since the start of the period measurement.

Further, in the case of FIG. 6, YES in step S _16.
Is is determined, snow REVERSE register is judge whether 1 to step S _17. If it is not 1, the determination is NO and the process returns to step S ₁ , but as described above, step S
This register is set to 1 by the execution of _{15. Then,} the process proceeds from step S ₁₇ to step S ₁₈ and the STEP register is set to 3 (see FIG. 6 (b)). Then, at step S ₁₉ , t '
Counter 7 received in the register for this interrupt
The value in the T register from the value of, that is, the zero-cross point Zero1
Subtract the time and store it in the PERIOD register.

That is, the size shown in FIG. 6 (c) becomes the length of one cycle, and in the subsequent step S ₂₀ , the content of t ′ is transferred to the T register and a new cycle measurement is started.

In step S _21, with the contents of the above PERIOD register CPU100 frequency ROM 8, issues a sound command to the tone generator 9. Therefore, a musical sound is generated from this point.

Now, in the case of FIG. 5 described above, again in the processing of the main flow after the next zero cross point (ZERO4), it jumps from step S ₅ to step S _16. SIGN now
Register is 2, a determination of YES in step S _16, continues in the same manner as described above Step S ₁₇ and _{→ S 18 → S 19 → S} 20
→ Perform sounding start processing of S _21, this time CP until Zero4 from zero-cross point Zero2 shown in FIG. 5 (c) as one cycle
The U100 recognizes and starts to produce a musical tone having a frequency based on this length (see FIG. 5 (d)).

In this way, the process of periodic measurement is started from the zero cross point next to the peak point with a large value, and the measurement is finished at the zero cross point next to the peak point on the same side as that peak point. One cycle of a 3-output waveform is extracted.

After the sound generation start process, in the main routine, the process proceeds from step S ₄ to step S ₂₃ , and it is judged whether or not the relative on process is performed. That is, specifically, it is judged whether or not the current peak value (b ') is larger than the previous peak value (c) by ONLEVII, that is, whether or not the extracted peak value suddenly increases during sound generation.

If vibration normal strings, since the natural attenuation, this step S ₂₃ is the determination NO, the the like if tremolo, while the previous string vibrations Finished attenuated, are operated string again, determination of step S ₂₃ is sometimes is YES.

In that case, step S ₂₃ jumps to step S ₈ the judge YES, it executes the preparation process of the start of sounding of steps S ₉ ~ step S _11. As a result, the STEP register becomes 1, and the operation exactly the same as the operation at the start of sounding is executed thereafter. In other words, Step S ₁₆ to S ₂₁ again
After that, the sound generation start process is executed to start the sound reproduction again.

Now, in the normal state by performing the steps S ₂₄ following the step S ₂₃ as described above, the coincidence comparison of the contents of content and SIGN register a ', the matched unless the process proceeds to S ₁₅ following the zero-crossing point interrupt provided to the process, if they match, so has already peak (positive / negative peaks) each pass having opposite characteristics, the process proceeds to step S _25, rEVERSE register whether to judge 1, if if NO The process returns to step S ₁ without any processing, but if this step S ₂₅
If in a determination of YES is made, a new cycle proceeds from step S ₂₅ to step S ₂₆ (pitch) to determine the t '
Subtract the T register contents from the register contents and
Set in register.

Then, in step S ₂₇ , the contents of the t ′ register are transferred to the T register, and in the subsequent step S ₂₈ , PE
Frequency (pitch) control based on the value of the RIOD register CPU100
Is performed on the frequency ROM 8 and the tone generator circuit 9.

That is, in the present embodiment, the change in the vibration frequency of the string is captured every moment, and the frequency control according to the change is performed in real time.

Then, from step S ₂₈ to step S ₂₉ , proceed to REVE
The next cycle is measured with the contents of the RSE register set to 0.

Then, the string vibration attenuates and the peak value becomes OFFLEV.
And come so falls below, in step S ₃₀ of the current
After determining that the value of the STEP register is “3”, the A / D converter 11 outputs the latch 1 as shown in FIG. 7 (c).
The waveform level value latched in 2 is the mute level value OFFLEV
When the following is detected (step S ₃₁ ), “1” is set in the OF register which was “0” until then, the count value of the counter 7 is set in the OFT register, and the process returns to step S ₁ . (step S ₃₂ ~S _34).

Since the peak value also falls below OFFLEV, even when the input waveform reaches its peak, the A / D converter 11 will
Waveform level value to be latched in that order does not exceed OFFLEV, without proceeds from step S _30, S ₃₁ to step S _38, the state where OF register becomes "1" is maintained. If the OFF string does not exceed OFFLEV, the length of one wavelength of the open string pitch of the relevant string, for example, in the case of the sixth string as described above, if it continues for 12 milliseconds or longer, the CPU 100 will display as shown in FIG. 7 (d). In step S ₃₅ , this is discriminated from the difference between the count value set in the OFT register and the current count value of the counter 7, and in step S ₃₆ the STEP register and OF register are cleared, and in step S ₃₇ CP to perform note-off processing (silence processing) to mute the musical tones that have been produced so far
U100 will give instructions to the tone generator circuit 9.

In this case, since the pitch extraction stop level value PITLEV is set to a value smaller than the muffling level value OFFLEV, as shown in FIG. 7 (a), the peak value is within the above 12 milliseconds.
Even if it is OFFLEV or less, it may be more than PITLEV, and Fig. 7 (e)
As shown in, subsequently the pitch extraction process of step S ₂₆ to S ₂₉ in between the 12 msec is performed, the tone is sounded at precise frequencies in until mute. Of course, if there is a sharp decay, the pitch extraction process will not be performed even during the above 12 ms.

If attenuation is only temporary, it again peak value exceeds the OFFLEV, CPU 100 is to determine this in step S _31, the OF register is cleared in step S _38, the silencing processing is not performed.

According to this embodiment, by temporarily mute playing, fast interrupt peak value is attenuated signal INT _a, even INT _b is not generated, the latch 12 is given a clock signal CL at all times, i.e. Figure 2 Latch command signal L shown in is High
Since the level is maintained, the output of the A / D converter 11 is passed through to the CPU 100 via the latch 12 and processed according to the given peak value, so that the mute response is improved.

In the above embodiment, the waveform level of the sixth string is
Although the sound is muted if it is less than OFFLEV for 12 milliseconds, it may be muted at the pitch period generated by the electronic guitar or at a longer time. Further, in the above embodiment, the CPU 100 performs interrupt processing at the zero-cross point immediately after each peak point to perform processing such as sound generation start, period calculation, relative on, and mute start. You may perform these processing directly at the time of leaving. In that case, the exact same result can be obtained. In addition, the same processing as described above may be performed, for example, by detecting the zero cross point of the straight line of the peak point. In addition, the way of taking a reference point can be variously changed.

Further, in the above embodiment, each process is executed in the main flow, but the same process may be executed in the interrupt process.

Furthermore, in the above embodiment, the present invention was applied to an electronic guitar, but the present 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.

[Effects of the Invention] As described in detail above, the present invention can be applied to a waveform input having a level larger than the second predetermined value even within a predetermined time during which the silencing process is started and the output sound is rapidly attenuated. Pitch extraction is performed and the acoustic signal is emitted at the correct frequency.
If the attenuation of the input waveform level is abrupt, pitch extraction will be discontinued promptly, eliminating wasteful processing after the mute instruction and improving the responsiveness of the next new musical sound generation processing and the start of pitch extraction processing. As a result, a smoother performance can be achieved.

[Brief description of drawings]

FIG. 1 is a diagram showing an overall circuit configuration of an input control device for an electronic musical instrument of an embodiment to which the invention is applied, and FIG. 2 is a time chart diagram showing waveforms appearing in respective parts in FIG. Figure 3 is a diagram showing a flowchart of the CPU interrupt routine,
FIG. 4 is a view showing a flow chart of the main routine of the CPU, FIGS. 5 and 6 are time charts showing the operation of each part at the start of sound generation, and FIG. 7 is a time chart showing the operation at the start of muffling. Is. 1 ... Input terminal, 4 ... Maximum peak detection circuit, 5 ... Minimum peak detection circuit, 6 ... Zero-cross point detection circuit, 7 ...
… Counter, 9 …… Sound source circuit, 12 …… Latch, 14,15…
… Flip-flop, 100… CPU, 101… Work memory, P1 to P6… Pitch extraction circuit.

Claims (1)

(57) [Claims] 1. A frequency measuring means for measuring the frequency of an input waveform signal, a sounding instructing means for instructing generation of an acoustic signal according to the frequency measured by the frequency measuring means, and a level of the input waveform signal is predetermined. When the time becomes equal to or less than a first predetermined value, a muffling instruction means for instructing muffling of an acoustic signal, and the level of the input waveform signal is the first for muffling.
And a second predetermined value smaller than the predetermined value, the measurement means for controlling the frequency measurement means to stop the measurement of the frequency.