JPS6142695A - Musical sound synthesization - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a musical tone synthesis method for synthesizing musical tone signals using modulation operations such as frequency modulation operations or amplitude modulation operations, and particularly relates to a musical tone synthesis method that synthesizes musical tone signals by using modulation operations such as frequency modulation operations or amplitude modulation operations, and in particular, it relates to a musical tone synthesis method that synthesizes musical tone signals by using modulation operations such as frequency modulation operations or amplitude modulation operations. This relates to making it possible to control the frequency components of ζ.

[Conventional technology]

Previously, Special Publication No. 54-33525, Special Publication No. 54-757
As disclosed in Japanese Patent Publication No. 58-29519, there is a known technique for synthesizing a musical tone signal having a desired overtone structure by frequency modulation calculation or amplitude modulation calculation in the audible frequency range.

[Problem that the invention seeks to solve]

However, in all of the above-mentioned conventional methods, a simple mononomial p modulation calculation is not sufficient to synthesize a musical tone with a satisfactory tone that has sufficient overtone components, and complex modulation using multiple or polynomials is not sufficient. I had to do some calculations. For this reason, the configuration of the arithmetic circuit becomes complicated and large, and in a system in which each arithmetic term is computed in a time-sharing manner, the speed of the control flow has to be increased, which tends to increase costs. As a method of synthesizing musical tones containing many overtone components using relatively simple calculations, the above-mentioned
As shown in No. 4-7570, a method has been considered in which a waveform having many frequency components is used as a modulating wave or a modulated wave, but the waveform that can be used for calculations is the one stored in the waveform memory. Because of this, there was a limit to the tones that could be synthesized.

[Means for solving problems]

This invention provides a method for synthesizing a musical tone signal based on a predetermined modulation operation using a modulating signal and a modulated signal, in which phase data for a waveform table used for generating a modulating wave taste or a modulated wave function is specified. The phase data is changed in the phase interval, and the function waveform generated from the waveform table based on the changed phase data is used for modulation calculation.

[Action of the invention]

By changing the phase data for the waveform table in a specific phase interval, the function waveform generated from the waveform table changes its waveform shape in the specific phase interval, and this function waveform itself contains many harmonic components. . Therefore, musical tone signals containing many harmonic components can be synthesized without performing complex modulation calculations such as polynomials.

〔Example〕

FIG. 1 is a block diagram showing an embodiment of the present invention in a frequency modulation (hereinafter abbreviated as F'M) calculation type musical tone synthesis method, which is roughly divided into a modulated wave function generator 10 and a modulated wave function. It includes a generator 20 and an adder 60 for performing phase modulation of a modulated wave, that is, a carrier wave. The modulated wave function generator 10 reads out the sine wave data sinωmt from the sine wave table 11 in accordance with the modulated wave phase angle data ωmt, multiplies it by the modulation index data ωmt in the multiplier 12, and outputs the result as modulated wave data. The adder 60 adds the modulated wave data E(s·sinωmt) output from the multiplier 12 to the carrier wave phase angle data ωpt, thereby performing phase modulation of the carrier wave.

The modulated wave function generation unit 20 generates phase angle data θ (=ωc t+
A predetermined modulated wave function is generated according to I(s·sinωmt), and a musical tone signal G is output based on this modulated wave function.

In the embodiment shown in FIG. 1, this modulated wave function generator 20
This invention has been applied to.

That is, the modulated wave function generating section 20 includes a shift circuit 21,
It is composed of a control circuit 22, a sine wave table 23, and a multiplier 24, and the phase angle data θ of the carrier wave inputted from the adder 30 is shifted by a predetermined number of bits toward the upper bit side or the lower bit side in the shift circuit 21. . The shift direction and shift amount in this case are instructed by the phase shift data SFT output from the control circuit 22, and the phase shift data SFT is output only in a specific phase section in one cycle of the phase angle data θ. Furthermore, the specific phase section in which the phase shift data SFT is output is changed in accordance with the timbre selection signal TC.

Therefore, if the amount of shift to the upper bit side is 10j and the amount of shift to the lower bit side is -j, the phase angle data θ will be doubled in the specific phase section ζ of one period (however, k = 21
j) be done.

The phase angle data θ' multiplied by the specific phase interval is inputted to the sine wave table 26 as an address signal. When phase angle data θ' is input to the sine wave table 23, sine waveform data sin θ' of a sine wave phase corresponding to this phase angle data θ'lζ is read out.

To simplify the explanation, the phase angle data θ is shown in Fig. 2 (a
), if the data simply increases (θ=
ωct), the control circuit 22 changes j=o, j=+1 as shown in FIG. Output phase shift data SFT. As a result, the shift circuit 21 outputs phase angle data θ' which is the original phase angle data θ multiplied by 21 in the phase interval from π to 2π, as shown in FIG. 2<c>.

As a result, from the sine wave table 26, as shown in FIG. 2(d), in the phase interval from π to 2π, 1
Instead of 72 cycles of sine waveform data, 1 cycle of sine waveform data sinθ' is read out.

That is, in a specific phase interval during one cycle of the original phase angle data θ, sine waveform data sin θ' having a waveform shape different from that of the remaining phase intervals is read out. The sine waveform data sinθ′ read from the sine waveform table 23 in this manner is supplied to the multiplier 24, where it is multiplied by amplitude coefficient data A (t) to control the amplitude setting. It is output as musical tone signal G.

This musical tone signal G has the waveform shape of the sine waveform data sinθ' read from the sine wave table 23 as shown in FIG. 2(d).
As shown in FIG. 3, since the phase is changed in a specific phase interval, it contains many harmonic components, resulting in a complex frequency spectrum as shown in FIG.

Therefore, a tone signal containing many harmonic components can be obtained with a simple configuration without performing complex modulation calculations using polynomials.

By the way, each parameter ωmt, I(t), ωct, TC, A(riha) used in this example is
It is given by a circuit as shown in FIG. In FIG. 4, a keyboard circuit 40 detects keys pressed on the keyboard of an electronic musical instrument and outputs key press data. Phase data generation circuit 41
generates modulated wave phase angle data ωmt and carrier wave phase angle data ωct that change in a period corresponding to the pitch of the pressed key in accordance with the key pressed data given from the keyboard circuit 40.

On the other hand, the envelope generator 42 generates modulation index data E(ri) and amplitude coefficient data A(ri) which sequentially change over time in response to the key-on signal KON generated from the keyboard circuit 40 when a key is suppressed. The data generation circuit 41 and the envelope generator 42 are supplied with a timbre selection signal TC from the timbre selection circuit 43, and ωct and ωm
The frequency ratio of t and the waveform shape of the time function of A(ri) are controlled according to the selected tone.

In the embodiment shown in FIG. 1, the phase angle data θ is changed by shifting the phase angle data θ to the upper bit side or the lower bit side by a predetermined number of bits, but as shown in FIG. A bit prohibition circuit 25 is provided in place of the shift circuit, and the bit data of, for example, the lower three bits of the phase angle data θ input to the bit prohibition circuit 25 is transmitted in a specific phase interval corresponding to the timbre selection signal TC. A control circuit 26 is provided that generates a control signal INH for inhibiting, for example, one cycle of phase angle data θ.
The control signal INH is generated only in a specific phase interval from π to 2π out of 0 to 2π, and in the phase interval from π to 2π, the lower 3 bits of the phase angle data θ are set to 0.
You can change it so that In this case, the sine waveform data si read from the sine wave table 23
As shown in FIG. 6, nθ' has a waveform shape that changes stepwise in the phase interval from π to 2π, and a musical tone signal G having a complicated waveform shape can be obtained.

In the above description, the present invention is applied to the modulated wave function generation section 20, but the present invention may be applied to the modulated wave function generation section 10 instead.

That is, the modulation wave function generating section 10 is configured as shown in FIG. The modulated wave phase angle data ωm is changed by shifting a predetermined number of bits to the upper bit side or the lower bit side.
t/ is input as the address signal of the sine wave table 11. As a result, a modulation wave function containing many harmonic components can be generated.

In this case, the shift circuit 16 and the control circuit 14 may be replaced with the configuration shown in FIG.

Also, a modulated wave function generation section 10 and a modulated wave function generation section 20
The present invention may be applied to both.

Furthermore, the output waveform data of the sine wave table 11 is fed back to the input side as shown by the broken line in FIG.
By modulating the phase angle data ωmt with this output waveform data, a musical tone signal G having more complex harmonic components can be obtained.

Furthermore, the control signals SFT and INH generated from the control circuits 22, 26.14 are not only the timbre selection signal TC,
The generation conditions may also be changed in response to an envelope waveform signal that changes over time.

FIG. 8 is a block diagram showing an embodiment of the present invention in an amplitude modulation (hereinafter abbreviated as AM) calculation type musical tone synthesis method, and the present invention is applied to the modulated wave function generating section 50. That is, the modulated wave function generating section 50 is connected to the shift circuit 5
1. The carrier wave phase angle data ωct is composed of a control circuit 52 and a sine wave table 53, and the carrier wave phase angle data ωct is converted into phase shift data SFT output from the control circuit 52 in the shift circuit 51 according to the timbre selection signal TC and the phase angle data ωct.
It is changed by shifting a predetermined number of bits to the upper bit side or lower bit side according to the change. Then, this changed phase angle data ωct' is stored in the sine wave table 5.
It is input as the address signal of 3.

As a result, the sine waveform data sinωct' corresponding to the phase angle data ωct' is read from the sine wave table 53. In this case, the phase angle data ωc, t is changed in a specific phase section of one cycle, and the sine wave table 56
Therefore, the sine wave table 56 generates a modulated wave function with a complex waveform similar to that shown in FIG. 2(d).

On the other hand, a modulated wave function generator 6 that modulates this modulated wave function
0 has a sine wave table 619, a multiplier 62, and a cosine wave table 63, and when modulated wave phase angle data ωmt is input to the sine wave table 61 as an address signal, the phase angle data is extracted from this sine wave table 61. Sine waveform data sinωmt corresponding to ωmt is read out. This sine waveform data sinωmt is multiplied by modulation index data (I) in a multiplier 62 and then supplied to the cosine wave table 63 as an address signal.Thereby, the cosine waveform data cos(I( S・s1nω
mt) is read out. This cosine waveform data cos(I
(s·sinωmt) is supplied to the multiplier 70 as a modulated wave function, and is multiplied by the modulated wave function to perform an amplitude modulation calculation. The output of this multiplier 70 is
0, and is multiplied by the amplitude coefficient data A (ri) to be output as a posttone signal G whose amplitude is controlled.

Therefore, in this embodiment as well, since the modulated wave function itself already contains many harmonic components, the musical tone signal G that is finally obtained also contains many harmonic components.

In addition, in this example as well, the modulated wave function is changed by the fifth
If you do it with the same configuration as shown in the figure,
Musical tone signals containing even more harmonic components can be generated. Further, the present invention may be applied only to the modulated wave function generating section 60, or may be applied to both of the modulated wave function generating sections 50.

By the way, by combining the waveform changing function of the modulated wave function or modulating wave function according to the present invention with other waveform changing functions,
By configuring the operator unit 1-0PU for generating a modulated wave function or a modulated wave function as shown in the figure, it is possible to generate a musical tone signal with a waveform shape that changes even more complicatedly.゛That is, the phase angle data
and the phase angle data
By shifting to the upper bit side or the lower bit side, it is doubled by one period (where k = 2''j, j is the shift amount, +J indicates the shift to the upper bit side, -j is the shift to the lower bit side) Indicates a shift to the bit side.This ±j is the data AS
The phase angle data kx indicated by FT is extracted. Next, convert the sine waveform data into a logarithm value of 1oysinx
This phase angle data kx is input as an address signal to the waveform table 92 stored in the waveform table 92.
The sine waveform data of AOIFsinkx is read from 2.

Next, this sine waveform data 1ofsinkx is transferred to the shifter 9.
6 and shifts the sine waveform data AoysiΩkx to the waveform data m-lay s by shifting it to the upper bit side or the lower bit side by the shift amount indicated by the waveform shift data DSFT given from the waveform control unit 91.
Change to in kx. Here, m is m=2thi, l indicates a shift to the upper bit side, and -i indicates a shift to the lower bit side.

This ±i is indicated by the data DSFT.

Next, this waveform data m-flay sin kx is input to the log-linear converter 94, and the waveform data of natural numbers (s
inkx)m. That is, when the shift amount ±i in the shifter 96 is set to i = 1 (when the output of the waveform table 92 is shifted by 1 bit to the upper bit side or the lower bit side), (sin k x )
2 or f;T waveform data is obtained.

Next, this waveform data (sin kx) rn is input to the gate 96 via the selector 95, and is output only in a specific phase section in which the control signal INH given from the waveform control section 91 is '1''. Positive and negative polarity sign data SD given from the waveform control unit ?1 are added to the waveform data (sin k x ) of the phase section and output to the outside.

Here, phase shift data ASFT, waveform shift data DSFT, select control signal SEL of selector 95, control signal INH, and code data SD are tone color selection signal TC.
are controlled differently depending on the Then, for a specific selected tone, the phase angle data kx outputted from the shifter 90 is selected by the selector 95 and outputted via the gate 96.

Therefore, the waveform shift amount ±i specified by DSFT is +1
．． The phase shift amount ±j specified by ASFT is set to the phase interval in which the O2 control signal INH becomes '0'' from π to 2π, and the selector 95 is set to the eight-power selection state (the output of the log-linear converter 95 is selectively output). When the sign data SD is positive in the phase interval from O to π, 5Ll as shown in FIG. 10(a)
The waveform data of lX is obtained only during the phase interval from O to π.

Further, by setting the data AsFT etc. output from the waveform control section 91 as shown in Table 1 below, waveform data having a waveform shape as shown in FIG. 10(b) can be obtained.

Table 1 Furthermore, by setting the data ASFT etc. output from the waveform control unit 91 as shown in the following Tables 2 to 5, the data as shown in FIGS. 10(C) to 10(f) Waveform data with a waveform shape can be obtained.

Table 2 Table 32 Table 4 Table 5 Therefore, by generating a modulated wave function or a modulated wave function using such an operator unit OPU,
It is also possible to generate modulating wave functions and modulated wave functions with more complex waveforms, as well as musical tone signals. In this case, the modulated wave function or the modulated wave function can be selectively generated by simply changing the phase angle data X input to the operator unit OPU, so the modulated wave function and the modulated wave function can be easily generated using a common circuit. This has the advantage of reducing costs.

It goes without saying that the present invention is applicable not only to FM and AM modulation calculations consisting of one term, but also to musical tone synthesis methods using multinomial, multiplex, or cyclic FM and AM modulation calculation formulas. .

Further, although dedicated waveform tables may be used to generate the modulating wave function and the modulated wave function, each function may be generated by using one waveform table in a time-division manner. In addition, the waveform table is not limited to sine waves.
Waveform data of cosine waves, triangular waves, rectangular waves, and other complex waveforms may be stored. Furthermore, the modulation calculation is not limited to digital calculation, but may be performed by analog calculation.

Furthermore, the conditions for generating the control signals SFT and INH generated from the control circuits 22, 26, 14.52 may be sequentially changed as time elapses from the time when the musical tone is generated.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, by changing the phase data for the waveform table in a specific phase interval, the waveform of the modulated wave or modulated wave prepared in advance in the waveform table can be changed with an extremely simple configuration. Since the waveform is changed to include more harmonic components and the modulation calculation is performed using this waveform, musical tone signals including more harmonic components can be synthesized using a simple modulation calculation formula. This has the effect of reducing the size and cost of the circuit, as well as allowing musical tone signals of various tones to be synthesized by simple control.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention in an FM calculation type musical tone synthesis method. The figure shows an example of the output waveform of each part of FIG. 1, FIG. 3 shows an example of the reciprocal spectrum of the musical tone signal obtained in the embodiment of FIG. 1, and FIG. FIG. 5 is a block diagram showing an example of a circuit that generates various calculation parameters to be used. FIG. 5 is a block diagram showing another example of a part that changes phase data in the embodiment of FIG. 1. FIG. 7 is a block diagram showing an embodiment in which the present invention is applied to a modulation wave function generator, and FIG. 8 is an embodiment of the present invention in an AM operation type musical tone synthesis method. A block diagram illustrating an example, FIG. 9, is used to generate a modulated wave function or modulating wave function by combining the waveform changing function of the modulated wave function or modulating wave function according to the present invention with other waveform changing functions. FIG. 10 is a block diagram showing one embodiment of the operator unit, and is a diagram showing an example of the shape of a function waveform obtained from the operator unit of FIG. 9. 10.60...Modulation wave function generation section, 20.50...
Modulated wave function generation unit, 11.23, 53.61... Sine wave table, 22, 26, 52... Control circuit, 13
．． 21.51...Shift circuit, 25...Bit inhibition circuit.

Claims (1)

[Claims] 1. In a musical tone synthesis method for synthesizing a musical tone signal based on a predetermined modulation calculation using a modulating signal and a modulated signal, the phase with respect to a waveform table used for generating a modulating wave or a modulated wave function is provided. A musical tone synthesis method comprising: changing data in the specific phase interval; and using a function waveform generated from the waveform table based on the changed phase data for the modulation calculation. 2. The musical tone synthesis method according to claim 1, wherein the modulation calculation follows a predetermined frequency modulation calculation formula. 3. The musical tone synthesis method according to claim 1, wherein the modulation calculation follows a predetermined amplitude modulation calculation formula. 4. The phase data is changed by prohibiting predetermined bit data among a plurality of bit data constituting the phase data in the specific phase interval. Any of the musical tone synthesis methods described in paragraph 3. 5. The phase data is changed by shifting the phase data to the upper bit side or the lower bit side by a predetermined number of bits in the specific phase section. Any of the musical tone synthesis methods described in Section 1. 6. Claim 1, wherein the specific phase section is set corresponding to the timbre of the musical tone signal to be synthesized.
A musical tone synthesis method according to any one of items 1 to 5.