JP3282438B2 - Music signal synthesizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tone signal synthesizer for synthesizing a tone signal by oscillating a vibration signal using a closed waveguide network, and more particularly to a filter provided in a closed loop of the waveguide network. The pitch compensation of the synthesized tone signal taking into account the signal delay time caused by the above, and the effective control of the variable control of the signal delay time in the loop during the tone generation. .

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 63-40199 discloses a basic configuration of a technique for oscillating and synthesizing a musical tone waveform signal using a closed digital waveguide network. This is a signal circulation path (closed digital waveguide network) that circulates digital waveform signals by connecting delay circuits and filters in a closed loop.
And a digital excitation signal is introduced into the circulation path to circulate the circulation path, thereby oscillating a waveform signal and extracting an output tone waveform signal from an appropriate point in the loop. The basic concept of this technique is to model the physical characteristics of a desired natural musical instrument such as a wind instrument or a stringed instrument using a closed digital waveguide network and thereby simulate the sound of the natural musical instrument. That is, the signal circulation path (closed digital waveguide network) models the physical propagation of a vibration signal traveling or reflecting in a medium such as a pipe or a string. As for the case of simulating a wind instrument, the signal circulation path corresponds to the tube portion of the wind instrument, and the signal delay time there simulates the length of the tube, and thereby the resonance of the tube portion. Set the characteristics. In addition, the filter provided in the signal circulation path simulates the attenuation of sound waves and other frequency characteristics at the ends, openings, holes, and the like of the tube,
Thereby, the timbre can be controlled. When simulating a stringed instrument, the signal circulation path corresponds to a string portion. As described above, the signal circulation path corresponds to the vibration generating portion of the physical sound source.

In a signal circulation path, the propagation and reflection of a signal at a physical boundary portion (for example, a vibration excitation portion such as a lead, an opening of a tube, or a mounting end of a string) in a propagation path of a vibration signal is considered. A signal junction part for modeling is appropriately provided. For example, a signal junction unit for modeling a vibration excitation unit includes a non-linear conversion unit. The signal junction for modeling the other physical boundary includes an arithmetic circuit that sorts and combines the traveling wave signal and the reflected wave signal. The non-linear converter for exciting the vibration signal includes, for example, a non-linear table. By introducing an appropriate electric pressure signal corresponding to a breath pressure or a bowed string operation into the loop of the signal circulation path, a signal obtained by nonlinearly converting the pressure signal by the nonlinear table circulates in the signal circulation path, and vibrates. The waveform signal is excited. In other cases, a noise signal or an appropriate initial waveform signal is used as the signal introduced into the signal circulation to excite the vibration waveform signal.

The signal delay time in the signal circulation path can be variably controlled by changing the number of delay stages of a delay circuit provided in the signal circulation path, thereby controlling the resonance characteristic in the signal circulation path. The pitch of the tone waveform signal synthesized in the signal circulation path can be set / controlled. In this case, the delay unit time in the delay circuit (the minimum unit, that is, the delay time for one stage, that is, one delay clock time or one sampling clock time) is constant. In Japanese Patent Application No. 1-102376 or Japanese Patent Application No. 1-125326, in a tone signal synthesizing apparatus using a closed loop signal circulation path as described above, a technique for interpolating outputs of a plurality of delay stages of a delay circuit (that is, a stage). Interpolation technique) is shown. In addition, Japanese Unexamined Patent Publication No.
No. 67,674 discloses a technique for realizing a delay of less than a unit delay time of the delay circuit by using an all-pass filter in a tone signal synthesizing apparatus using a closed loop signal circulation path as described above.

[0005]

Incidentally, the filter provided in the signal circulation path exhibits not only the original amplitude-frequency characteristic but also the phase delay characteristic. Occurs at Such a signal delay due to the filter varies, in particular, depending on the filter coefficient (ie the cut-off frequency) and also on the frequency of the signal. Particularly, in an IIR (infinite response filter) having a feedback loop in the filter circuit, such a phase delay characteristic is remarkable. Therefore,
The total delay time of the signal circulation path is the sum of the delay time set by the delay circuit and the signal delay time by the filter (however, if other delay elements exist in the closed loop, the delay is of course taken into consideration. ), Desired pitch (pitch)
In order to synthesize a tone signal having the following, it is not sufficient to simply set the delay time of the delay circuit in accordance with the desired pitch, and it is necessary to compensate for the signal delay time caused by the filter.

In the case of this type of technology, the basic pitch adjustment method is to switch the number of delay stages of the delay circuit, but this alone can adjust only the unit delay time. In order to compensate for the signal delay time caused by the filter, it is necessary to perform a delay adjustment of less than the unit delay time in the delay circuit. As a pitch adjustment method conventionally considered, there is a technique of interpolating outputs of a plurality of delay stages of a delay circuit (that is, an inter-stage interpolation technique) as described above. Conventionally, this inter-stage interpolation technique has been employed only when a pitch modulation effect such as vibrato is realized, and is used for compensating signal delay time by the above-described filter. That was not considered. In particular, what should be noted in this type of inter-stage interpolation technique is that an interpolation circuit is inserted in the closed loop of the signal circulation path, and this interpolation circuit functions as a low-pass filter, and the high-frequency May be unnecessarily attenuated. Also, when trying to realize a temporal change in timbre characteristics or the like by time-varying the filter coefficients during the production of a musical tone, be careful not to generate noise or the like by the delay control operation for compensation. There is a need to.

A first object of the present invention is to provide a tone signal synthesizing apparatus which synthesizes a tone signal by exciting a vibration signal in a closed loop including a delay element and a filter element. It is another object of the present invention to provide a tone signal synthesizing apparatus capable of appropriately compensating for a change in a signal delay time of a loop caused by a change in a filter coefficient and synthesizing a tone having a desired pitch. In particular, it is an object of the present invention to provide an advantageous pitch adjustment technique when the filter coefficient fluctuates during tone generation.

When an all-pass filter is provided in a closed loop as in the prior art, a signal delay (a fractional delay) less than a unit delay time is obtained by a linear delay characteristic independent of a frequency band of an input signal by the all-pass filter. ) Can be realized. However, if the delay time of the all-pass filter is variably controlled during generation of a musical tone, a problem arises that noise may be caused by a large change in the decimal value of the signal delay time of the loop. For example, when the delay time corresponding to the decimal value “0.9” is set by the all-pass filter, by further changing the signal delay time of the entire loop, if the carry occurs, the decimal value “0.0” Must be switched immediately so that the delay time corresponding to "" is set by the all-pass filter, and a sudden change in the delay time occurs in the part of the all-pass filter, which becomes noise. Thus, the delay control by the all-pass filter is not suitable for variably controlling the delay time over a wide range.

The present invention has been made in view of the above points, and a second object thereof is to provide a tone signal for synthesizing a tone signal having a pitch corresponding to a signal delay time in a closed loop including at least a delay element. A tone signal synthesizing device capable of solving a problem such as generation of noise during tone generation by selectively using a control mode for variably controlling the signal delay time of the loop before and after the tone generation. It is intended to provide a device.

[0010]

In order to solve the above-mentioned first problem, a musical sound signal synthesizing apparatus according to the present invention forms a closed loop for circulating a signal, and includes a delay unit and a filter unit. Signal circulating means provided therein, excitation means for introducing a signal into a loop of the signal circulating means to excite vibration, and setting a signal delay time in the loop according to a desired musical tone pitch, whereby the Pitch setting means for causing a tone to vibrate at a desired pitch in a loop; and a plurality of different delay times in the loop in response to a change in a filter coefficient of the filter means during the generation of a tone. The signal delay time of the loop is adjusted by interpolating and synthesizing the delay output signals at the points, thereby changing the signal delay time due to the change in the filter coefficient. Those comprising an interpolation means for compensating for.

In order to solve the second problem, the tone signal synthesizing apparatus according to the present invention has an input means for inputting an excitation signal and a closed loop for circulating the signal input by the input means. And a delay means for delaying a signal circulating in the closed loop is included in the closed loop, and the signal repeatedly circulates in the loop to thereby generate a vibration of a tone having a pitch corresponding to a signal delay time in the loop. A signal circulating unit that generates, a signal control unit that sets a signal delay time in the loop according to a desired pitch, and sets a delay time by the delay unit in accordance with the delay time; A delay control filter for controlling the characteristic of the filter in order to variably control the signal delay time in the loop at or before the start of musical tone generation. First means, after generating the start of the musical tone,
While the musical tone is being generated, in order to variably control the signal delay time in the loop, a delay output signal at a plurality of points having different delay times in the loop is interpolated and synthesized using a variable coefficient. A second means.

Further, the tone signal synthesizing apparatus according to the present invention has an input means for inputting an excitation signal, a closed loop circulating the signal input by the input means, and a signal circulating in the closed loop. Signal circulating means for generating a vibration of a musical tone having a pitch corresponding to a signal delay time in the loop by repeatedly circulating the signal in the closed loop. Delay control means for setting a signal delay time in the loop according to a pitch, and setting a delay time by the delay means in accordance with the delay time; and a first filter for delay control inserted in the loop And at or before the start of the generation of the musical tone, the first filter is implemented by the first filter to variably control the signal delay time in the loop. First means for setting filter characteristics, and a second filter for delay control inserted in the loop, wherein after the musical tone starts being generated, the loop is generated while the musical tone is being generated. And a second means for variably controlling a coefficient to be given to the second filter in order to variably control the signal delay time.

[0013]

The signal circulating means and the exciting means constitute an electronic closed-loop sound source similar or similar to the physical model type sound source using the closed type waveguide network, and the total delay time in the loop of the signal circulating means. A tone signal having a pitch corresponding to the tone signal is synthesized. When the filter coefficient is changed to control the tone color of the tone being generated, for example, by manually operating an appropriate tone color control operator, the signal delay time at the filter means changes. Although the total delay time in the loop of the signal circulating means may fluctuate as it is, the tone signal synthesizing apparatus for solving the first problem according to the present invention appropriately copes with the provision of the interpolating means. I am trying to do it. That is, in response to the change in the filter coefficient during the generation of the musical tone, the interpolation means performs an operation of interpolating the delay output signals at a plurality of points having different delay times in the loop, thereby causing the change in the filter coefficient. The variation in the signal delay time of the loop is compensated for. By interpolating a plurality of signals having different delay times, the signal delay time of the entire loop can be finely adjusted according to the interpolated delay time. Therefore, by interpolating the delay time so as to compensate for the variation in the delay time in the filter section,
The pitch of the obtained musical tone can be controlled so as not to change.

According to the present invention, since the adjustment is performed by interpolation, even when the adjustment is performed during generation of a musical tone, there is little possibility that noise will be caused. As described above, the insertion of the interpolation circuit into the loop may function as a low-pass filter. However, the interpolation is performed in response to the time-varying change of the filter coefficient, that is, the time-varying change control of the timbre. Therefore, the effect could be underestimated. That is, compared to a case where an interpolation circuit is inserted in order to obtain a desired steady tone, a case where an interpolation circuit is inserted corresponding to the time variation control of the timbre has a lower steady-state characteristic resulting from the low-pass filter characteristic by interpolation. Since there is little effect on the tone color, the advantage of interpolation calculation that can perform smooth signal delay time control with a simple configuration for pitch adjustment during musical tone generation is better than the disadvantage of unwanted low-pass filter characteristics due to interpolation. Is larger. Further, if the high frequency cut by the undesired low-pass filter characteristics by interpolation is not so important for realizing the intended tone, the influence of the undesired low-pass filter characteristics is further reduced. Would. Therefore, performing the interpolation operation of the signal delay time for the pitch compensation according to the filter coefficient change during the generation of the musical tone as in the present invention has considerable advantages.

In one embodiment of the tone signal synthesizing device for solving the first problem, the loop may include an all-pass filter. As described above, a signal delay (fractional delay) of less than a unit delay time can be realized by the linear delay characteristic independent of the frequency band of the input signal by the all-pass filter. The signal delay (integer delay) in units of the unit delay time is realized by variably setting the number of delay stages in the delay means. When starting generation of a musical tone having a desired pitch, the pitch setting means subtracts a filter delay time corresponding to the filter coefficient set by the filter means from a signal delay time of the entire loop corresponding to the desired pitch. Then, the delay time by the delay means is set based on this difference. Then, the number of delay stages of the delay means is set corresponding to the integer part of the quotient obtained by dividing the delay time corresponding to the difference by the unit delay time, and the coefficient of the all-pass filter is set corresponding to the decimal part of the quotient. , The delay time corresponding to the decimal part is realized by the all-pass filter. This enables fine pitch adjustment. However, as described above, it is better to refrain from controlling the delay time of the all-pass filter during generation of a musical tone.
This is because when the signal delay time has to be compensated as described above due to a change in the tone color control filter coefficient during tone generation, noise may be caused by a large change in the decimal value of the signal delay time. Because. For example, when the delay time corresponding to the decimal value “0.9” is set by the all-pass filter and a carry occurs, the delay time corresponding to the decimal value “0.0” is set by the all-pass filter. The switching must be performed immediately, and a sudden change in the delay time occurs in the portion of the all-pass filter, which may cause noise. Therefore, even when the delay time adjustment control by the all-pass filter is performed, the signal delay time adjustment control for the pitch compensation according to the filter coefficient change during the tone generation is preferably performed by the interpolation calculation as in the present invention. . That is, it does not cause noise.

The method of adjusting the signal delay time of the entire loop in accordance with the desired pitch when starting the generation of a musical tone of the desired pitch by the pitch setting means uses an all-pass filter as described above. The invention is not limited to this, and any other means may be used. For example, when the generation of a musical tone having a desired pitch is started, a filter delay time corresponding to the filter coefficient set by the filter means is subtracted from a signal delay time of the entire loop corresponding to the desired pitch. The unit delay time itself in the delay means may be variably set based on the difference. However, calculating an appropriate unit delay time in response to a change in the filter coefficient requires a considerable amount of calculation time.
It would be advantageous if such calculations could be avoided during musical tone generation. Therefore, even when the control of adjusting the signal delay time of the loop by the variable control of the unit delay time is performed, the control of adjusting the signal delay time for pitch compensation according to the change of the filter coefficient during tone generation is performed as in the present invention. There is an advantage in performing the calculation by interpolation. That is, it is possible to omit troublesome calculation processing during generation of a musical tone. As described above, the control of adjusting the signal delay time by the variable control of the all-pass filter and the unit delay time at the start of the tone generation and the control of adjusting the signal delay time by the interpolation during the tone generation are mutually complementary and advantageous. , So that their combination gives good results.

In the tone signal synthesizing apparatus for solving the above-mentioned second problem according to the present invention, first means and second means are provided as means for variably controlling the signal delay time in the loop. (1) The case where the variable control is performed at or before the start of the generation of the musical tone, and the case (2) the case where the variable control is performed during the generation of the musical tone after the start of the generation of the musical sound. A control mode for variably controlling the signal delay time of the loop can be selectively used before and after the start of musical tone generation. By such use, (1) as the first means used for variable control at the start of or before generation of a musical tone, means that may cause noise when the delay time is largely variably controlled (for example, Even if the above-mentioned all-pass filter is used, since the sound has not yet been generated, the effect that such noise can be prevented from actually occurring can be avoided. After the start, the second means used for the variable control during the generation of the musical tone may be a means that does not cause noise when the delay time is largely variably controlled (for example, the above-described interpolation means Or a finite impulse response filter), so that noise is not generated by loop delay time control during sound generation. There is an effect that.

In one embodiment, the tone signal synthesizing apparatus for solving the second problem may include an all-pass filter as a filter in the first means. The filter in the second means may be constituted by a finite impulse response (FIR) filter, and may equivalently correspond to a low-pass filter, that is, a delay interpolator. That is, at or before the start of generation of a musical tone, delay control is performed by an all-pass filter having an advantage that frequency characteristics are not affected, in order to adjust a loop delay time or correct a pitch in advance, and a desired musical tone is generated. Get the pitch. Then, during the generation of the musical tone, the above-mentioned adverse effect due to the variation of the coefficient of the all-pass filter can be avoided in order to positively vary the musical tone pitch or to compensate / correct an unwanted pitch variation. As described above, in the second means, variable control of the delay time of the loop or fluctuation control of the pitch is performed by using the delay interpolation means or the finite impulse response filter or the low-pass filter without using the all-pass filter. In this case, the low-pass filter, that is, the delay interpolation means, has the disadvantage of changing the frequency characteristics of the signal, but has good linearity of the delay change, and is easy to control even when the delay amount is largely changed. Since it has advantages, it is extremely effective to use it for control during musical tone generation. At the start of (or before) the generation of such a musical tone
The delay control modes of the first and second means are used in a mutually complementary manner during and during tone generation (that is, after tone generation) to adjust or vary signal delay time in a loop, that is, to perform pitch compensation or To perform the fluctuation control,
This is extremely advantageous because both disadvantages can be counteracted and the advantages of both can be exploited.

[0019]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. [Example of Hardware Configuration] FIG. 1 shows an example of a hardware configuration of an electronic musical instrument according to an embodiment of a tone signal synthesizing apparatus according to the present invention. This electronic musical instrument includes a CPU (Central Processing Unit) 10, a ROM (Read Only Memory) 11, a RA
A microcomputer unit including an M (random access memory) 12 and the like is provided as a main control device. The performance operator block 13 includes various manual or foot-operated operations such as a keyboard for selecting / designating a musical tone pitch, a wheel, a joystick, and a pedal for controlling a tone color, a volume or a pitch of the musical tone. A group of operators that are operated in real time during the performance by the player, such as a child, a breath controller, a controller using gestures and body actions, etc., are collectively illustrated for convenience. One or more may be provided as appropriate. The panel block 14 collectively shows various switches (tone selection switches, volume adjustment switches, effect selection switches, etc.) and indicators related thereto arranged on the panel surface of the electronic musical instrument for convenience. It is.

The tone synthesizer 15 performs processing for synthesizing a tone signal in accordance with the same principle as that of the closed waveguide network described above, and of course, tone synthesis on a plurality of channels is also possible. The tone synthesis unit 15 is configured to realize a desired tone synthesis algorithm.
Dedicated hardware circuit or DSP (digital
A signal processor) circuit or a microprocessor can be used as appropriate. The digital musical tone signal synthesized by the musical tone synthesizing unit 15 is converted into an analog signal by a digital-analog converter 16, supplied to a sound system 17, and acoustically generated.

The ROM 11 has a program storage for storing an operation program of the CPU 10 and a parameter data storage for storing a tone synthesis parameter set corresponding to various preset timbres / voices. Further, if necessary, a storage unit or the like for storing various programs for setting the tone synthesis algorithm in the tone synthesis unit 15 may be provided. Each of these storage units may be composed of a separate ROM circuit. RAM12
Stores various parameters arbitrarily set by the user using the working RAM unit and the performance operators or panel operators of the blocks 13 and 14 and various parameters automatically created or rewritten by arithmetic processing. And a parameter data RAM unit to be used. CPU10
In accordance with the control by the control unit, the performance control block 13 and the panel block 14 are scanned, and various processes based on the scanning results (for example, tone generation assignment process of a pressed key, a tone synthesis program required in accordance with factors such as a selected timbre, etc.) From the ROM 11 and transfers it to the tone synthesizer 15, or various tone synthesis parameters selected or created in accordance with factors such as the selected tone color, operation of various controls, or results of arithmetic processing. , And transferring the data to the tone synthesizer 15).

[Explanation of the Musical Sound Synthesizing Unit 15]
FIG. 2 is a functional block diagram showing an example of a musical tone synthesis operation processing algorithm realized by the above. In FIG. 2, a signal circulating unit 30 forms a closed loop that delays and circulates a digital waveform signal, and includes a variable delay circuit 31 for delaying a waveform signal and a filter 32 for tone color control. The resonance characteristic in the loop can be controlled by controlling the delay time in the loop, and the pitch of the musical tone to be synthesized can be set. The signal circulating unit 30 includes a multiplier 33 for variably controlling the gain of the circulating signal, and an adder 34 for introducing a signal for excitation into the loop. In the loop of the signal circulating unit 30, an all-pass filter 20 and an interpolation circuit 40 are inserted to adjust a signal delay time. The variable delay circuit 3
As is well known, 1 can be constituted by a switchable multi-stage shift register circuit or the like when it is constituted by a dedicated discrete hardware circuit, and is a read / write random access memory (RAM) when it is a program type. Can be configured using.

The excitation waveform generator 35 corresponds to an excitation unit for exciting vibration in the loop of the signal circulator 30, and generates, for example, an appropriate noise signal. This noise signal is converted by the multiplier 36 into appropriate envelope waveform data E.
The amplitude is controlled by G1 during the sounding time, and then input to the adder 34 to be introduced into the closed loop of the signal circulation unit 30. This appropriately amplitude-controlled noise signal is introduced into the signal circulating unit 30, delayed by the delay circuit 31, the delay amount is finely adjusted by the all-pass filter 20 and the interpolation circuit 40 as necessary, and The frequency characteristic is controlled, and the gain is appropriately controlled by the multiplier 33 in accordance with the gain control parameter G.
, A vibration signal is oscillated in the signal circulation unit 30. This principle of generating a vibration signal is based on the principle of music synthesis by a closed waveguide network described as the prior art. The filter 32 controls the amount of harmonics of the musical tone synthesized in this loop and the speed of its attenuation, and its characteristic is determined by the filter coefficient C supplied as described above as one of the musical tone synthesizing parameters. (Eg, cut-off frequency and other filter characteristics) are set / controlled, and eventually the tone color of the synthesized musical tone is controlled.

The vibration signal oscillated by the signal circulation unit 30 is
It is taken out from an appropriate point in the closed loop, input to the multiplier 37 for amplitude adjustment, and amplitude is appropriately controlled by appropriate envelope waveform data EG2. Further, the excitation waveform signal output from the multiplier 36 is input to the multiplier 38, and the amplitude is appropriately controlled by appropriate envelope waveform data EG3. Then, the outputs of the multipliers 37 and 38 are added and synthesized by the adder 39 and output as a tone signal. This is because by adding an excitation waveform signal with an appropriate amplitude to the vibration signal oscillated by the signal circulating unit 30, the synthesized musical sound waveform can be variously controlled. Of course, the present invention is not limited to this. The multiplier 38 and the adder 39 may be omitted, and the vibration signal oscillated by the signal circulating unit 30 may be output as it is as a tone signal after being appropriately amplitude-controlled.

The algorithm for calculating the vibration signal oscillating portion including the signal circulating portion 30 and the excitation waveform generating portion 35 shown in FIG. 2 is merely an example (and is considerably simplified for simplicity of explanation). However, the present invention is not limited to this, but any arithmetic algorithm that follows the principle of music synthesis using a closed waveguide network can be used.
It is needless to say that everything from simple to complex, and from known to unknown, can be applied to the present invention. For example, as the excitation means for exciting vibration in the closed loop of the signal circulation means, a configuration for introducing a predetermined initial waveform signal to the closed loop, or a configuration for introducing an impulse signal to the closed loop, or a pressure signal imitating breath pressure Is known to be introduced into a closed loop, and is passed through a non-linear conversion table provided in the closed loop to perform nonlinear conversion. These configurations may be replaced with the excitation waveform generator 35. Further, the configuration of the signal circulating unit 30 is not limited to the simple loop as shown in FIG. Is also good.

In the tone synthesis principle based on such a closed waveguide network, the total delay time required for a signal to go through a closed loop in the signal circulating unit 30 is expressed by:
There is a clear correlation between the frequency of the vibration signal oscillated in the loop, that is, the pitch of the musical sound synthesized in the loop, and by appropriately setting the delay time, the desired vibration frequency, that is, the musical sound pitch Can be realized. This correlation is determined by a model or an operation algorithm adopted as the signal circulation unit and the excitation unit. For example, the vibration frequency may correspond to the reciprocal of the total delay time of the loop, or the vibration frequency may correspond to the reciprocal of twice the total delay time of the loop. In the case of the example of FIG. 2, the frequency of the vibration signal oscillated by the signal circulating unit 30 (the pitch of the synthesized tone signal) corresponds to the reciprocal of the total delay time in the signal circulating unit 30.

In FIG. 2, when the all-pass filter 20 and the interpolation circuit 40 are not considered, the total delay time in the signal circulating unit 30 is calculated from the sum of the delay time set in the delay circuit 31 and the signal delay time in the filter 32. Become. Of course, if there is another delay element to be noted, a delay time corresponding to the delay element is added. The delay circuit 31 is capable of changing the number of delay stages, and includes a control parameter Dx
Variably sets the number of delay stages. Basically,
By variably setting the control parameter Dx according to the desired musical tone pitch and thereby variably setting the number of delay stages of the delay circuit 31, variable control of the delay time in the closed loop is performed. However, this is not enough, and it is necessary to compensate for the delay amount in consideration of the signal delay time by the filter 32. In this embodiment, the all-pass filter 20 and the interpolation circuit 40 are provided for the compensation. These will be described in detail later.

The unit time of the operation (operation of delay and filter, etc.) per musical sound signal sample in the musical sound synthesizing section 15 is set by the generation cycle of the sampling clock CK. That is, the delay processing for each stage in the delay circuit 31 is controlled by the sampling clock CK. Therefore, the frequency of the sampling clock CK is set to fs
(Hz) and the number of delay stages set by the control parameter Dx is Dx, the signal delay time assigned to the delay circuit 31 is expressed by the following equation.

## EQU1 ## Dx / fs (second)

The sampling clock CK is supplied to the filter 32
To set the calculation unit time in the filter 32. The signal delay time of the filter 32 is determined by the specific configuration of the filter. FIG. 3 shows an example of the filter 32. This is an infinite response filter (IIR)
This is an example in which a low-pass filter (LPF) is configured by using this method. A unit delay circuit 26 for delaying the signal by one stage in accordance with the sampling clock CK; an adder 27 for subtracting a signal fed back from the unit delay circuit 26 from a filter input signal; A multiplier 28 for multiplying the output of the multiplier 28 with a signal fed back from the unit delay circuit 26. The output of the adder 29 is input to the unit delay circuit 26, and the filter This is a configuration that is taken out as an output.

In the case of the filter shown in FIG. 3, the signal delay Dlpf is expressed by the following equation. Note that the unit of the delay amount Dlpf is the number of clocks with one operation unit time as one clock, that is, the number of delay stages (the same meaning as the number of delay stages of the delay circuit 31). That is, if the unit delay time is the same, the delay amount uniquely corresponds to the actual signal delay time.

Dlpf = C sin θ / {θ * (1−C cos θ)} Here, θ is θ = 2π * fp / fs. fp (Hz) is the pitch frequency (pitch) of the signal input to the filter, and fs (Hz) is the frequency of the sampling clock CK as described above. Of course,
* Is a multiplication symbol.

As shown in the above equation 2, the signal delay time of the filter 32 changes depending on the filter coefficient C. Therefore, for example, when the user uses the performance operators or panel operators of the blocks 13 and 14 in FIG. 1 to variably control the filter coefficient C in real time during performance, the signal delay by the filter 32 is performed. The time fluctuates as appropriate during the performance of the music (for each musical tone corresponding to an individual note or during the generation of one musical tone), and as it is, it corresponds to the fluctuation of the total delay time of the loop Since the pitch of the synthesized musical tone fluctuates, it is extremely important to appropriately compensate for this fluctuation. Of course,
The configuration of the filter 32 is not limited to the configuration shown in FIG. 3, and any other configuration may be used, and the correlation between the coefficient and the signal delay time in the filter is determined according to the configuration. For the above compensation, in this embodiment, the signal delay time is adjusted using the all-pass filter 20 at the start of generation of each musical tone, and the signal delay time is adjusted using the interpolation circuit 40 during generation of the musical tone. Is adjusted. This will be briefly described below.

First, the adjustment of the signal delay time by the all-pass filter 20 will be described. That is, in the signal circulating unit 30 in the tone synthesizing unit 15, apart from the filter 32 for tone color control, the all-pass filter 2 for signal delay
0 is provided, and the all-pass filter 20 controls a fine delay amount (a delay amount of a decimal part) of the delay circuit 31 that is shorter than the delay unit time. The setting of the delay time by the all-pass filter 20 is performed at the start of generation of each musical tone, and the once set delay amount is not changed during musical tone generation. As described above, the decimal part is changed from “0.9” to “0.0” or “0.0” by the carry or carry of the signal delay amount data as described above.
This is to avoid a sudden change such as from “0.9” to “0.9”, which adversely affects the musical tone being generated, such as noise. As is apparent from consideration of such a purpose, when such an abrupt change does not occur (for example, when the decimal part changes from “0.1” to “0.2”), It can be understood that a modification in which the control of adjusting the signal delay time by the all-pass filter 20 is used together even during the generation of a musical tone can be implemented.

FIG. 4 shows an example of the configuration of the all-pass filter 20, in which a unit delay circuit 21, multipliers 22 and 2 are shown.
3. It includes adders 24 and 25. The input signal is input to the unit delay circuit 21 via the adder 24, and the output of the unit delay circuit 21 is multiplied by the coefficient -α by the multiplier 22 to add the adder 2.
4 and the output of the adder 24 is
, And the output of the unit delay circuit 21 is added by the adder 25 and output. The all-pass filter 20 can perform linear delay control independent of the band of the input signal by varying the coefficient α by a decimal value in the range of 0 to 1. The signal delay time in the all-pass filter, that is, the delay amount Dapf is determined according to the filter coefficient α in a relationship represented by the following equation, for example.

## EQU3 ## Dapf = (1−α) / (1 + α)

Here, the desired tone pitch frequency is defined as Pn
(Hz), the total delay amount Ds in the signal circulating unit 30 required to obtain the pitch frequency Pn is determined by the following equation. fs (Hz) is the frequency of the sampling clock CK for setting the unit delay time as described above.

Ds = fs / Pn

In this embodiment, first, at the start of musical tone generation, the total delay amount Ds in the signal circulating unit 30 corresponding to a desired musical tone pitch is determined by the above equation (4). Then, the filter 3 for timbre control is obtained by the above equation (2).
2. The signal delay amount Dlpf at 2 is obtained. Then, the difference between the two is calculated as shown in the following Expression 5, and the delay amount (the number of delay stages) Dx to be shared by the delay circuit 31 and the delay amount to be shared by the all-pass filter 20 are obtained from the integer part Di and the decimal part Df. Calculate Dapf. That is, the integer part Di is added to the delay circuit 3
1 is set as a delay amount (number of delay stages) Dx to be shared,
The decimal part Df is set as the delay amount Dapf to be shared by the all-pass filter 20. At this time (that is, at the start of musical tone generation), it is assumed that the interpolation in the interpolation circuit 40 is not performed, and the coefficient β is set to “0”, for example.

Ds-Dlpf = Di + Df Dx = Di Dapf = Df

The filter coefficient α of the all-pass filter 20
Is obtained, for example, according to the above equation 3 according to the delay amount Dapf determined in this way. For example, the filter coefficient α thus determined is fixed during generation of the musical tone.

Next, control during generation of a musical tone will be described. If the filter coefficient C for tone color control is changed during tone generation, a new filter delay amount Dlpf 'is first obtained according to the equation (2). Next, a new filter delay amount Dlpf 'and a delay amount Dapf of the all-pass filter 20, which is fixed during sound generation as described above, that is, Df, are subtracted from the desired total delay amount Ds as in the following equation (6). The delay amount Di ′ + Df ′ to be shared by the delay circuit 31
Ask for. Here, Di 'is an integer part, and Df' is a decimal part. Since the delay circuit 31 can only perform a unit delay,
The integer part Di 'is set as a new delay stage number Dx, and the delay (delay less than the unit delay time) according to the decimal part Df' is set by the interpolation circuit 40. That is, the interpolation coefficient β of the interpolation circuit 40 is determined according to the value of the decimal part Df ′.

Β is determined according to Ds−Dlpf′−Df = Di ′ + Df ′ Di ′ = Dx Df ′.

The interpolation circuit 40 interpolates and synthesizes a plurality of delayed output signals corresponding to different delay times in the signal circulating section 30 according to a predetermined interpolation formula. An example of the interpolation is shown in FIG. It seems. In the example shown in FIG. 2, the interpolation circuit 40 includes a unit delay circuit 41, a multiplier 4
2 and 43, and an adder 44. The output of the delay circuit 31 is further delayed by one stage by a unit delay circuit 41, and the delayed output is multiplied by a coefficient β by a multiplier 42. On the other hand, the output of the delay circuit 31 is input to the multiplier 43, and is multiplied by the coefficient “1-β”.
Then, the outputs of the multipliers 42 and 43 are added by an adder 44 so that the output of the adder 44 circulates in a loop.
Therefore, the primary interpolation is performed between the delay output signal of the number of delay stages Dx corresponding to the integer part Di ′ and the delay output signal of one more stage according to the coefficient β corresponding to the value of the decimal part Df ′. Make up the circuit. In the case of such a primary interpolation circuit, Df ′ = β may be set.

As described above, the adjustment of the signal delay time of the signal circulating unit 30 (the signal delay corresponding to the decimal part Df '), which is required according to the change of the filter coefficient C for controlling the timbre during the tone generation, is described. , By the interpolation circuit 40. In connection with the tone synthesis unit 15, parameters for envelope formation (for example, key-on and key-off information and parameter information for forming a desired envelope waveform)
Various envelope waveform data (eg, EG
1 to EG3) are provided, but not shown. The parameter G for controlling the loop gain of the signal circulating unit 30 may be envelope waveform data that is generated in conjunction with key-on / off and fluctuates with time.

[Specific Example of Processing by CPU] In this embodiment, the CPU 10 performs the above-described calculation processing of setting the delay amount according to the musical tone pitch and the filter coefficient. Therefore, a specific example of the processing by the CPU 10 will be described below. -Description of Main Routine- Referring to FIG. 5, a schematic example of the main routine of the CPU 10 will be described. First, when a power switch is turned on, a predetermined initialization process is performed, and then an operation event detection process is performed in step 50. Here, the operation state of the key switches and other switches and the operation elements in the performance operation block 13 and the panel block 14 is detected, and it is checked whether or not the operation state has changed (whether or not there is an event). For example, when there is an ON event or OFF event of a switch, an ON event flag or an OFF event flag corresponding to the switch is set. When the operation amount of an operator having a multi-step operation position such as a joystick, a wheel, or a volume changes, the operation amount or the movement amount is stored in a register corresponding to each operator.

Next, in the voice switch processing in step 51, the tone / voice newly selected or changed by the operation of the performance operator block 13 or the panel block 14 (or the first one) according to the content of the event flag. Reads out from the ROM 11 or RAM 12 data or parameters necessary for synthesizing a tone (tone / voice specified in the initialization process), and transfers the data or parameter to the tone synthesizer 15 for storage. The tone synthesizer 15 synthesizes a tone signal having a timbre / voice determined by these data or parameters based on the data thus transferred and stored. The data or parameters are also stored in an appropriate buffer memory of the CPU 10 so that the data of the currently selected timbre / voice can be referred to as needed.

Next, in the key-on process of step 52,
According to the content of the event flag, when a key-on event occurs, necessary processing for preparing to synthesize a musical tone of the new pressed key is performed. The key-on process includes a signal delay time adjustment (that is, pitch adjustment) control to be performed at the start of musical tone generation, taking into account the delay time of the tone color control filter. Next step 53
In the key-off process, when there is a key-off event, a process for attenuating or erasing a tone related to the new key release is performed according to the content of the event flag. In order to generate musical tones on a plurality of channels, as is well known, a process of allocating a pressed key corresponding to a key-on event to an appropriate musical tone synthesizing channel is appropriately performed.

Next, in the operator processing in step 54, when the operation state of various real-time control operators in the performance operator block 13 and the panel block 14 changes according to the contents of the event flag, The necessary processing corresponding to the operation state of is performed. This operator processing includes a signal delay time adjustment (that is, pitch adjustment) control to be performed when the filter coefficient for tone color control changes during generation of a musical tone, taking into account the delay time of the filter for tone color control. In step 55, other necessary processing is performed. Then, the process returns to step 50. Thus, the main routine from steps 50 to 55 is repeated.

FIG. 6 shows an example of a key-on process performed in step 52 of the main routine. First, in step 60, the presence or absence of a key-on event is checked,
If S, this process is continued, but if NO, the process returns. In step 61, a process of allocating a key or a note related to the key-on event to any tone generation channel is performed. In step 62, a key code K indicating a key or a note related to the key-on event
Frequency Pn indicating the pitch of the musical tone to be generated based on C
(Hz) is determined. In the next step 63,
In accordance with the following equation, an operation “Ds = fs” for calculating the total delay amount Ds in the signal circulating unit 30 required to obtain a desired musical tone pitch frequency Pn (Hz) under a predetermined sampling frequency fs (Hz) / Pn ". It should be noted that these steps 62 and 63 can be replaced by a table reading process instead of an arithmetic process. For example, it is also possible to adopt a configuration in which data of the total delay amount Ds is read at a time according to a key code KC related to a key-on event.

In the next step 64, the parameter indicating the coefficient C of the filter 32 is extracted as the initial parameter Co from the tone synthesis data for the currently selected / set tone / voice stored in the buffer memory. By substituting the initial parameter Co of the filter coefficient into the filter coefficient C of the predetermined filter delay time calculation formula as shown in the above equation 2, for example, the initial value of the filter 32 corresponding to the coefficient Co (that is, Signal delay D)
lpfo is calculated, for example, as follows. Dlpfo = Co sin θ / ｛θ * (1−Co cos θ)} In determining the initial parameter Co, not only the filter coefficient data stored in the buffer memory but also the operation of other tone control operators The state (the operation state at the start of sound generation) may be considered. The calculation here can be replaced with table reading.

In the next step 65, the initial filter delay amount Dlpfo obtained in step 64 is subtracted from the total delay amount Ds obtained in step 63 as in the equation (5).
The delay amount “Ds−Dlpfo” to be shared by the delay circuit 31 and the all-pass filter 20 is calculated. It includes an integer part Di and a decimal part Df as follows. Ds−Dlpfo = Di + Df In the delay amount Di + Df thus obtained, the integer part Di
Is the delay stage number setting data Dx of the delay circuit 31, and the fractional part Df is the delay amount Dap to be shared by the all-pass filter 20.
Let f be the data to be set.

In the next step 66, the value of the filter coefficient α necessary to obtain the delay amount Dapf = Df calculated in the step 65 is calculated in accordance with a predetermined all-pass filter delay time calculation formula such as the above equation (3). I do. For example, in the case of using the equation (3), it is possible to calculate the filter coefficient α by the following equation: α = (1−Df) / (1 + Df) This operation can be replaced by reading the table.

In the next step 67, the parameters Dx and α for setting the desired pitch calculated as described above are set.
And various other parameters (for example, parameters for forming an envelope) for starting generation of a musical sound.
To send to. At this time, "0" is sent out as the parameter β of the interpolation circuit 40, so that the interpolation operation of the signal delay time is not performed at the start of generation of the musical sound. Music synthesis section 1
At 5, the tone synthesis process is started based on the transmitted various parameters, and the generation of tone signals is started.

-Description of Pitch Adjustment Processing During Musical Tone Generation- FIG. 7 shows an example of operation processing performed in step 54 of the main routine, and shows processing relating to operation controls for timbre control. is there. First, at step 70, it is checked whether there is an operator event for tone color control. If YES, this process is continued, but if NO, the process returns. For example, it is checked whether or not the data m indicating the operation amount of the tone control operator has changed. If the operator for tone color control is operated during generation of a musical tone, the result of step 70 is YES, and the routine goes to step 71. In step 71, an appropriate sensitivity parameter s is calculated (e.g., multiplied) with respect to the operation amount data m of the timbre control operator, the sensitivity is adjusted, and the initial parameter Co of the timbre control filter coefficient is calculated ( For example, add)
The calculation result is temporarily determined as the filter coefficient C of the filter 32. The sensitivity parameter s is appropriately determined according to the selected tone color / voice type and the like.

In the following steps 72 to 75, a limit process is performed on the filter coefficient C provisionally determined as described above. In step 72, it is determined whether the temporarily determined filter coefficient C is smaller than a predetermined minimum value Cmin. If YES, the predetermined minimum value Cmin is set as the filter coefficient C in step 73. If NO, the process proceeds to step 74, and it is checked whether the temporarily determined filter coefficient C is larger than a predetermined maximum value Cmax. If YES, a predetermined maximum value C is determined in step 75.
Set max as the filter coefficient C. Thus, the range of change of the filter coefficient C is limited to a predetermined range. This range is appropriately changed depending on the type of the filter in the filter 32.
Cmin = 0.01 and Cmax = 1.00. Minimum value Cmi
It is better not to set n to 0 but to give a small value to some extent, such as 0.01.

Next, in step 76, the filter coefficient C determined as described above according to the real-time tone color control operation is substituted into the filter coefficient C of a predetermined filter delay time calculation formula such as the above equation (2). The signal delay amount Dlp of the filter 32 corresponding to the changed filter coefficient C
f ′ is calculated, for example, as follows. Dlpf ′ = C sin θ / {θ * (1−C cos θ)} This operation can also be replaced with table reading.

In the next step 77, the total delay amount D corresponding to the desired pitch is calculated as described below, as in the equation (6).
From s, the new filter delay amount Dlpf ′ and the delay amount Dapf of the all-pass filter 20 that is fixed during sound generation as described above are subtracted, and the delay amount Di ′ + Df ′ to be shared by the delay circuit 31 is obtained. Here, Di ′ is an integer part,
Df 'is a decimal part. Ds−Dlpf′−Dapf = Di ′ + Df ′ The integer part Di ′ thus obtained is set as a new delay stage number setting parameter Dx of the delay circuit 31. The decimal part Df ′ corresponds to a delay amount less than the unit delay time that cannot be realized by the delay circuit 31. In the next step 78, a process of determining the interpolation coefficient β of the interpolation circuit 40 according to the value of the decimal part Df 'is performed. The interpolation coefficient β can be determined based on the value of the decimal part Df ′ by performing a predetermined calculation or table reading according to the interpolation formula. As described above, in the case of primary linear interpolation, the decimal part D
The value of f ′ may be used as it is as the interpolation coefficient β.

In the next step 79, the filter coefficient C changed as described above and the parameters Dx and β for setting the desired pitch calculated so as to adjust the pitch in accordance with the change are set in the musical tone. It is sent to the synthesizing unit 15.
Note that the coefficient α of the all-pass filter 20 is maintained as initially set at the start of sound generation. The tone synthesizer 15 performs tone synthesis processing based on the transmitted various parameters, and generates a tone signal having a changed tone at a compensated desired pitch. The process of FIG. 7 is performed in real time each time the filter coefficient C is changed in accordance with the operation of the operator for tone color control.

FIG. 8 shows an example of the key-off process performed in step 53 of the main routine. First, in step 80, it is checked whether or not there is a key-off event.
If S, this process is continued, but if NO, the process returns. In step 81, various key-off parameters (for example, parameters for setting the envelope waveform to the release state) are transmitted in accordance with the channel to which the key related to the key-off event is assigned.
When attenuated sounding is performed with the key-off, the tone color control for the key-off may be automatically performed. In this case, the filter coefficient C changed for key-off is transmitted, and the same processing as in steps 76 to 79 in FIG. 7 is performed, so that the desired pitch is adjusted so as to adjust the pitch in accordance with the change in the filter coefficient C. The setting parameters Dx and β are calculated, and these parameters are also stored in the tone synthesis unit 1.
5

[Explanation of Other Embodiments or Modifications] As a means for adjusting the delay time according to the filter coefficient for tone color setting / control at the start of musical tone generation, an all-pass filter as shown in the above embodiment is used. However, other appropriate means may be used. For example, the sampling clock C
The control may be performed by variably controlling the frequency fs (Hz) of K, that is, by variably controlling the unit delay time in the delay circuit 31. For example, when the generation of a musical tone having a desired pitch is started, the filter delay amount corresponding to the filter coefficient C is calculated from the signal delay amount Ds of the entire loop corresponding to the desired pitch calculated based on a certain reference sampling frequency fso. Dlpf is subtracted, and a delay time “(Ds−Dlpf) corresponding to the difference“ Ds−Dlpf ”is subtracted.
The sampling frequency fs may be variably set so that “× (1 / fso)” can be realized by the integer delay of the delay circuit 31. That is, when Dx is a certain integer, (Ds−Dlpf) × (1 / fso) = Dx ×
What is necessary is just to find the sampling frequency fs that satisfies (1 / fs). In this case, of course, both Dx and fs may be variably controlled.

As described above, in the above embodiment, the processing of the various calculation steps is such that instead of actually performing the calculation, the address of the variable data is input to a table prepared in advance, and the solution is immediately read. Of course, the configuration can be changed to Further, in the above embodiment, the filter 32 for tone color control is not limited to a low-pass filter, and any type of filter may be used. In such a case, when using a complicated filter whose signal delay characteristic cannot be obtained by a calculation formula, the delay characteristic is measured in advance and the coefficient versus delay amount data is stored based on the measured value. A table may be created and the filter delay amount data may be obtained by reading the table. Also, when the filter delay amount can be obtained by a calculation formula, the calculation speed can be increased by using a table. In this case, as described above, for a value that is not stored in the table, an approximate solution can be obtained by interpolating the output read from the table, thereby saving the storage capacity of the table. Can be.

The configuration of the interpolation circuit 40 is not limited to the primary interpolation as shown in FIG. 2, but may be a multi-order interpolation such as a secondary interpolation or a tertiary interpolation. In that case, the delay output signals are respectively extracted from a plurality of appropriate delay stages in the delay circuit 31, and
These may be interpolated by a predetermined interpolation coefficient. Further, the interpolation circuit 40 may be inserted in any part as long as it is in the loop of the signal circulation unit 30. It is needless to say that the present invention can be implemented not only by the software processing shown in the above embodiment but also by a dedicated hardware circuit.

[Explanation of Embodiment for Solving the Second Problem] The above embodiment is mainly described as an embodiment for solving the first problem of the present invention. However, the same embodiment can be taken as an embodiment for solving the second problem of the present invention. Further, as a modification, the filter 32 for tone color control may not be required. That is, even if the filter 32 for controlling the timbre is not provided,
An embodiment that solves the above problem is feasible. In this case, for example, in the key-on process of FIG. 6 executed at the start of musical tone generation, even if the initial delay amount Dlpfo obtained in step 64 is Dlpfo = 0, the total delay amount Ds corresponding to the desired pitch is not satisfied. Since it is possible to include a fraction less than the unit delay time, in step 65, Ds = Di +
From Df, it is necessary to determine the delay amount Dapf = Df to be shared by the all-pass filter 20. Therefore, in that case, the delay circuit 3 of the desired total delay time Ds of the loop
The portion exceeding the delay time Dx assigned by 1 (that is, the delay less than the unit delay time) is set to the delay amount Dapf = Df to be shared by the all-pass filter 20.

In the embodiment for solving the second problem, it is desirable that the interpolation circuit 40 variably control the amount of delay of the loop during the generation of a musical tone by the variation of the tone color filter coefficient as in the above embodiment. The present invention is not limited to the purpose of compensating / correcting a non-existent pitch change, but may be executed for other purposes, for example, for the purpose of actively controlling the pitch of a generated musical tone with time. FIG. 9 shows an example of such a case, and shows a pitch change process for performing a tone pitch change control during tone generation. This pitch change processing is executed at an appropriate place in the main routine of FIG. 5 (for example, the operation processing of step 54 and other processing of step 55).

In FIG. 9, first, at step 90, it is checked whether or not any key is being turned on. If YES, the process proceeds to the next step 91, but if NO, the process returns. This is because this pitch change processing is performed only during sound generation. Therefore, in this step 90, instead of checking whether or not the key is on, it may be checked whether or not any sound is being generated. In the next step 91, it is checked whether or not any pitch change event has occurred (for example, it is checked whether or not there is an event such as operation of a pitch change operator or a change in the value of pitch control data). If YES, the process proceeds to step 92, where necessary processing for changing the pitch Pn of the musical tone to the changed pitch Pn 'is performed. NO
If so, return. In step 93 following step 92, as in step 63 in FIG.
A total delay amount Ds 'corresponding to n' is obtained. Next, in steps 94, 95, and 96, steps 77, 78,
A process substantially the same as 79 is performed.

That is, in step 94, as shown in the following equation, the variable delay is set at the start of sound generation from the total delay amount Ds 'corresponding to the changed pitch Pn' as described above, and is fixed at the set value during sound generation. The delay amount Dapf of the all-pass filter 20 and the like are subtracted to obtain the delay amount Di '+ Df' to be shared by the delay circuit 31. Ds'-Dapf-Dlpf = Di '+ Df' Dlpf indicates the delay amount due to the filter 32 for tone color control, and is 0 if the filter 32 is not provided. If the filter 32 for tone color control is provided and its coefficient is not changed during tone generation, the value of Dlpf will correspond to the value Dlpfo.
Also, if a filter 32 for tone color control is provided,
If you change the coefficient even during musical tone generation, Dlp
The value of f will correspond to said value Dlpf '.

The integer part Di ′ thus obtained is set as a new delay stage number setting parameter Dx of the delay circuit 31. The decimal part Df ′ corresponds to a delay amount less than the unit delay time that cannot be realized by the delay circuit 31. In the next step 95, a process of determining the interpolation coefficient β of the interpolation circuit 40 according to the value of the decimal part Df ′ is performed. The interpolation coefficient β can be determined based on the value of the decimal part Df ′ by performing a predetermined calculation or table reading according to the interpolation formula. As described above, in the case of linear interpolation of the first order, the value of the decimal part Df ′ may be used as it is as the interpolation coefficient β. In the next step 96, the changed desired pitch P
Each parameter D obtained as described above corresponding to n ′
x, β, etc. are sent to the musical sound synthesizer 15. In this case as well, the coefficient α of the all-pass filter 20 is kept as initially set at the start of sound generation. The tone synthesizer 15 performs tone synthesis processing based on the transmitted various parameters, and generates a tone having a changed desired pitch.

A further modification will be described. As a means for variably controlling the signal delay time of the loop of the signal circulating unit 30 to less than the unit delay time at the start (or before) of the tone generation, the above-described embodiment employs an all-pass mode. Filter 20
However, the present invention is not limited to this, and a part of the delay time to be variably controlled may be shared by the interpolation circuit 40. That is, the interpolation circuit 40 has a drawback that an undesired frequency characteristic is given to a musical tone due to its low-pass filter characteristic. In such a range, the interpolation circuit 40 may be used as a means for variably controlling the delay time at (or before) the start of musical tone generation. . Also, as a filter for performing delay control at the start (or before) of musical tone generation,
The filter is not limited to the all-pass filter 20 and other filters for delay control may be used. Means for performing delay control during generation of a musical tone include an interpolation circuit 4
The filter is not limited to 0, and any other appropriate filter, for example, a finite impulse response (FIR) filter equivalent to an interpolation circuit may be used.

Some of the inventions and embodiments extracted from the above embodiments are summarized and listed as follows. 1. Forming a closed loop that circulates the signal, and a signal circulating means having a delay means and a filter means in the loop, an excitation means for introducing a signal into the loop of the signal circulating means to excite vibration, Pitch setting means for setting a signal delay time in the loop in accordance with a desired tone pitch, thereby causing the tone to vibrate in the loop with the desired pitch, and the filter during tone generation The signal delay time of the loop is adjusted by interpolating and synthesizing the outputs of a plurality of points having different delay times in the loop in response to the change of the filter coefficient of the means. A tone signal synthesizing device comprising: an interpolating means for compensating for a variation in a signal delay time. 2. When starting the generation of the musical tone having the desired pitch, the pitch setting means calculates a filter delay time corresponding to the filter coefficient set by the filter means from a signal delay time of the entire loop corresponding to the desired pitch. 2. The tone signal synthesizing device according to claim 1, wherein the delay time is set by the delay means based on the difference. 3. The pitch setting means includes an all-pass filter inserted in the loop, and a delay of the delay means corresponding to an integer part of a quotient obtained by dividing the delay time corresponding to the difference by a unit delay time of the delay means. Set the number of stages, set the coefficient of the all-pass filter corresponding to the decimal part of the quotient,
3. The tone signal synthesizing apparatus according to claim 2, wherein the delay time corresponding to the decimal part is realized by the all-pass filter. 4. 4. The tone signal synthesizing device according to claim 3, wherein the coefficient of the all-pass filter set at the start of the tone generation is not changed during the tone generation. 5. When starting the generation of the musical tone having the desired pitch, the pitch setting means calculates a filter delay time corresponding to the filter coefficient set by the filter means from a signal delay time of the entire loop corresponding to the desired pitch. 2. The tone signal synthesizing apparatus according to claim 1, wherein the unit delay time is variably set based on the difference. 6. The pitch setting means is responsive to a change in the filter coefficient of the filter means during generation of the musical tone, and calculates a filter delay time corresponding to the changed filter coefficient from a signal delay time of the entire loop corresponding to the desired pitch. 6. The tone signal synthesizing apparatus according to any one of claims 1 to 5, wherein the number of delay stages by the delay means and the interpolation coefficient of the interpolation means are set based on the difference. 7. The pitch setting means sets the number of delay stages of the delay means corresponding to an integer part of a quotient obtained by dividing the delay time corresponding to the difference by a unit delay time of the delay means, and corresponds to a decimal part of the quotient. 7. The tone signal synthesizing device according to claim 6, wherein an interpolation coefficient of said interpolation means is set, and a delay time corresponding to said decimal part is realized by said interpolation means.

8. An input means for inputting an excitation signal, and a closed loop circulating the signal input by the input means, and a delay means for delaying a signal circulating in the closed loop are included in the closed loop; A signal circulating means for generating a tone vibration having a pitch corresponding to the signal delay time in the loop by repeatedly circulating the signal through the loop; and setting the signal delay time in the loop according to a desired pitch. Including delay control means for setting a delay time by the delay means corresponding to the delay time, and a filter for delay control inserted in the loop,
First means for controlling the characteristics of the filter to variably control the signal delay time in the loop at or before the start of generation of a musical tone; and In order to variably control the signal delay time in the loop, using a variable coefficient,
A second means for interpolating and synthesizing the delay output signals at a plurality of points having different delay times in the loop. 9. An input means for inputting an excitation signal, and a closed loop circulating the signal input by the input means, and a delay means for delaying a signal circulating in the closed loop are included in the closed loop; A signal circulating means for generating a tone vibration having a pitch corresponding to the signal delay time in the loop by repeatedly circulating the signal through the loop; and setting the signal delay time in the loop according to a desired pitch. A delay control means for setting a delay time by the delay means in accordance with a delay time; and a first filter for delay control inserted in the loop, wherein the loop is set at or before the start of generation of the musical tone. A first means for setting characteristics of the first filter so as to be realized by the first filter so as to variably control a signal delay time in the loop; A second filter for controlling the input delay, the second filter being adapted to variably control the signal delay time in the loop during the generation of the tone after the generation of the tone. And a second means for variably controlling the applied coefficient. 10. The filter according to item 8 or the first filter according to item 9 includes an all-pass filter,
10. The tone signal synthesizing apparatus according to the above item 8 or 9, wherein the filter is a finite impulse response filter.

[0066]

As described above, according to the present invention, when a tone signal having a pitch determined according to the total delay time in the signal circulating means is synthesized by the signal circulating means and the exciting means, the tone being generated is generated. When the filter characteristics are variably controlled in order to control the tone color of the sound signal, the interpolation means compensates for the fluctuation of the signal delay time caused by the control.
By interpolating multiple signals with different delay times,
Since the signal delay time of the entire loop can be finely adjusted in accordance with the interpolated delay time, pitch adjustment control can be performed smoothly so that the pitch of the obtained musical tone does not change. That is, since the delay time control is performed by interpolation, there is little possibility that noise will be caused even when the tone is generated, and the arithmetic processing is relatively simple, so that it is suitable for real-time control.

Further, according to the present invention, the first means and the second means are provided as means for variably controlling the signal delay time in the closed loop of the signal circulating means.
(1) The case where the variable control is performed at or before the start of the generation of the musical tone, and (2) the case where the variable control is performed during the generation of the musical tone after the start of the generation of the musical sound. A control mode for variably controlling the signal delay time of the loop before and after the start of generation can be selectively used. (1) Used for variable control at the start or before the start of generation of a musical tone Even if a means (for example, the above-mentioned all-pass filter) that may cause noise when the delay time is largely variably controlled is used as the first means, no sound is generated yet. While it is possible to avoid the actual occurrence of noise, (2) the variable control during the generation of a musical tone after the start of the generation of the musical tone As a second means used for the above, a means (for example, the above-described interpolation means or a finite impulse response filter) which does not cause noise when the delay time is largely variably controlled is used, so that a loop during sound generation is used. There is an effect that noise can be prevented from being generated by the delay time control. As described above, the delay control modes of the first and second means are used in a mutually complementary manner between when the musical sound is generated (or before the musical sound is generated) and during the musical sound is generated (that is, after the musical sound is generated).
It is extremely advantageous to perform the adjustment or the fluctuation control of the signal delay time in the loop, that is, the pitch compensation or the fluctuation control, since both disadvantages can be canceled and both advantages can be utilized.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a hardware configuration of an electronic musical instrument according to an embodiment of a tone signal synthesizing apparatus according to the present invention.

FIG. 2 is a functional block diagram showing an example of a tone synthesis operation algorithm implemented by a tone synthesizer in FIG. 1;

FIG. 3 is a functional block diagram showing one configuration example of a tone color control filter provided in a signal circulating unit in FIG. 2;

FIG. 4 is a functional block diagram showing a configuration example of an all-pass filter provided in a signal circulating unit in FIG. 2;

FIG. 5 is a flowchart schematically showing an example of a main routine executed by a CPU (central processing unit) in FIG. 1;

FIG. 6 is a flowchart showing one embodiment of a key-on process executed in the main routine of FIG. 5;

FIG. 7 is a flowchart showing an example of an operator process executed in the main routine of FIG. 5;

FIG. 8 is a flowchart showing one embodiment of a key-off process executed in the main routine of FIG. 5;

FIG. 9 is a flowchart showing an example of a pitch changing process executed in the main routine of FIG. 5;

[Explanation of symbols]

Reference Signs List 10 CPU (central processing unit) 11 ROM (read only memory) 12 RAM (random access memory) 13 performance operator 14 panel 15 musical sound synthesizer 30 signal circulator 31 delay circuit 32 tone color control filter 22, 23, 28, 33, 36, 37, 38, 42, 4
3 Multiplier 24, 25, 29, 34, 39, 44 Adder 35 Excitation waveform generator 20 All-pass filter 40 Interpolator 21, 26, 41 Unit delay circuit

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G10H 7/08

Claims (3)

(57) [Claims] An input means for inputting an excitation signal; and a delay means for forming a closed loop for circulating the signal input by the input means and delaying a signal circulating in the closed loop. Signal circulating means for generating a tone vibration having a pitch corresponding to the signal delay time in the loop by repeatedly circulating the signal through the loop; and a signal delay time in the loop according to a desired pitch. And a delay control means for setting a delay time by the delay means in accordance with the delay time, and a filter for delay control inserted in the loop, at or before the start of musical tone generation, First means for controlling the characteristics of the filter for variably controlling the signal delay time in the loop; and And second means for interpolating and synthesizing delayed output signals at a plurality of points having different delay times in the loop using a variable coefficient in order to variably control the signal delay time in the loop. Signal synthesizer. 2. A closed loop, comprising: input means for inputting an excitation signal; and a delay means for forming a closed loop for circulating a signal input by the input means and for delaying a signal circulating in the closed loop. Signal circulating means for generating a tone vibration having a pitch corresponding to the signal delay time in the loop by repeatedly circulating the signal through the loop; and a signal delay time in the loop according to a desired pitch. And a delay control means for setting a delay time by the delay means in accordance with the delay time; and a first filter for delay control inserted in the loop, at the start of generation of the musical tone or In the previous, the first control signal is used to variably control the signal delay time in the loop.
And a second means for setting the characteristics of the first filter so as to be realized by the filter described above, and a second filter for delay control inserted in the loop. A second means for variably controlling a coefficient applied to the second filter in order to variably control a signal delay time in the loop during generation. The first filter wherein the billing said filter or claim 2 of claim 1 comprises all-pass filter, tone according to claim 1 or 2, wherein the second filter is a finite impulse response filter Signal synthesizer.