JPH03241398A - Musical tone synthesizing device - Google Patents

Abstract

PURPOSE:To synthesize the musical tone of a tone color being similar to a natural musical instrument without enlarging the device scale by dispersing an arrival signal to a prescribed position in the time base direction by a filter, in the prescribed position of a loop means, reflecting its signal to a supply side, or allowing it to transmit to a supply destination. CONSTITUTION:An excitation signal generated by an exciting circuit 10 is inputted to a bidirectional transmission circuit 30 through a junction 20, outputted from an output terminal T1, a sound of a resonance tube terminal part is given by allowing the signal to pass through a low-pass filter ML, and its signal is reinputted to the bidirectional transmission circuit 30, and fed back to the exciting circuit 10 through the junction 20. In such a state, in the bidirectional transmission circuit 30, filters FC3, FC4 for dispersing and outputting an input signal to itself in the time base direction are connected to a prescribed position, and a signal which arrives in its connecting position is allowed to transmit to a supply destination of the signal or reflected to a supply side of the signal through the filters FC3, FC4. In such a way, a musical tone of a wind instrument is synthesized faithfully without enlarging the device scale.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a musical tone synthesis device suitable for use particularly in synthesizing wind instruments and synthesizing voices.

"Prior Art" A method is known in which a model obtained by simulating the sound production mechanism of a natural musical instrument is operated, thereby synthesizing the musical tones of a natural musical instrument. The most basic model of a wind instrument is known to have a structure in which a nonlinear amplification element that simulates the elastic characteristics of a reed is connected to a bidirectional transmission circuit that simulates a resonant tube.

In this model, when a signal is output from the nonlinear amplification element, this signal is input to the bidirectional transmission circuit as a traveling wave signal, reflected at the terminal of the bidirectional transmission circuit, and this reflected wave signal is transmitted bidirectionally. It is fed back to the nonlinear amplification element via the circuit. Then, the nonlinear amplification element and the bidirectional transmission circuit enter a resonant state, whereby a synthesized sound of a wind instrument is generated.

Now, in general, the diameter of the resonance tube of a wind instrument is not constant; for example, in the case of a trumpet, as illustrated in FIG. 7, the diameter of the resonance tube increases toward the terminal end. Here, since the tube diameter affects the admittance to air pressure waves, in a resonant tube as shown in FIG. 7, scattering occurs at various parts within the tube due to changes in admittance. and,
As a result of scattering of air pressure waves in accordance with the shape of the tube within the resonant tube, a musical tone with a tone unique to each wind instrument is generated.

The resonance tube shown in FIG. 7 can be approximated by a structure in which cylinders #1 to #5 are connected, as illustrated in FIG. 8. This kind of structure requires two people as shown in Figure 9.
It can be simulated by cascading the output four-terminal circuits.

In FIG. 9, SF3 and SF are cylinder #
This is a shift register that simulates the propagation delay of air pressure waves in #3 and #4.

Further, A3 and A4 are adders, and M and -M4 are multipliers. l+k, -kSl attached to multipliers M1 to M4,
Each k is a multiplication coefficient. The cross-sectional area of cylinder #3 is Sl,
Assuming that the cross-sectional area of cylinder #4 is 84, the value of k is determined by the following equation (1).

k=Main C'' (1) S, + S3 Corresponds to the air pressure wave from the shift register SF that propagates inside the cylinder #3 and enters the connecting surface T34 with the cylinder #4. A signal is output. Then, the output signal of the shift register SF is multiplied by the coefficient 1 (1+k) by the multiplier M. As a result of this multiplication, the cylinder #4 passes through the connecting surface 734.
A signal corresponding to the air pressure wave propagating to is obtained, and this signal is input to a circuit (not shown) corresponding to the shift register SF3 of the next stage four-terminal circuit via the adder A4. Further, the output signal of the soft register SF is multiplied by a coefficient k by a multiplier M. As a result of this multiplication, the connecting surface T34
A signal corresponding to the air pressure wave reflected at is obtained, and this signal is inputted via adder A to the shift register SF of the four-terminal circuit in the preceding stage and a corresponding circuit (not shown).

Similar processing is performed on the output signal of the shift register SF, and the output signal of the shift register SF is converted to the connection plane T by the multiplier M4.

4 outputs a signal corresponding to the air pressure wave transmitted to the cylinder #3 side, and the multiplier M3 outputs a signal corresponding to the air pressure wave transmitted to the cylinder #3 side.
A signal corresponding to the air pressure wave reflected to the cylinder #4 side is output from the cylinder #4. The same operation as described above is performed in the four-terminal circuits at the front and rear stages of the four-terminal circuit shown in FIG. According to the circuits connected in cascade in this way, it is possible to simulate the propagation of air pressure waves in the case of the pipe shape shown in Fig. 8, and approximately simulate the resonant pipe of a natural musical instrument as shown in Fig. 7. can be simulated. Note that this type of technology is disclosed in, for example, Japanese Patent Laid-Open No. 63-40199.

``Problem to be Solved by the Invention'' By the way, in the conventional musical tone synthesis device, in order to faithfully reproduce the timbre of a wind instrument, it was necessary to provide a large number of four-terminal circuits as shown in FIG. For this reason, there is a problem in that the musical tone synthesis device becomes large-scale. In addition, DSP (
When musical tone synthesis is performed by arithmetic processing using a digital signal processor or the like, there is a problem in that the amount of calculation increases, making real-time musical tone synthesis difficult.

This invention was made in view of the above-mentioned circumstances, and it is possible to faithfully simulate the scattering of air pressure waves in a resonance tube without increasing the scale of the device.
It is an object of the present invention to provide a musical tone synthesis device capable of synthesizing musical tones with timbres close to those of natural musical instruments.

"Means for Solving the Problems" The present invention comprises an excitation means that generates an excitation signal based on an input signal, and a loop means that performs at least delay processing on the excitation signal and repeatedly circulates the excitation signal. In a musical tone synthesis device that generates a musical tone signal by bringing the means and the loop means into a resonant state, a filter is connected to a predetermined position of the loop means, and the filter outputs the signal after dispersing it in the time axis direction; It is characterized in that a signal arriving at the connection position is transmitted through the filter to the signal supply destination, or is reflected to the signal supply side.

"Operation" According to the above configuration, at a predetermined position of the loop means, the signal arriving at the position is dispersed in the time axis direction by the filter, and the signal is not reflected to the supply side or transmitted to the supply destination. It will be done. Therefore, signal processing equivalent to the case where signals are reflected and transmitted at a plurality of consecutive nodes including the connection position of the filter is performed.

"Example" Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a musical tone synthesizer according to an embodiment of the present invention. In the figure, IO is an excitation circuit that simulates the mouthpiece of a wind instrument, and 30 is a bidirectional transmission circuit that simulates a resonant pipe. Furthermore, the junction 20 inserted between the excitation circuit IO and the resonance circuit 30 simulates the scattering of air pressure waves at the connection between the mouthpiece section and the resonance tube.

At this junction 20, the output signal from the bidirectional transmission circuit 30 and the output signal from the excitation circuit 10 are added by an adder A and input to the bidirectional transmission circuit 30, and the output signal from the adder A and the output signal from the excitation circuit 10 are added together and input to the bidirectional transmission circuit 30. The output signals of the circuit 30 are added by an adder A and input to the excitation circuit 10.

The excitation circuit IO includes a subtracter B0, a low-pass filter 12,
It is composed of an adder A, a ROM (read only memory) 15, multipliers M4, M, 7, and INV. When a musical tone is generated, this excitation circuit IO is given information corresponding to the blowing pressure P and the amplitude E (an amount inversely proportional to the pressure when the mouthpiece is held in the mouth) from a musical tone control circuit (not shown).

Then, based on this information and the feedback signal PR from the bidirectional transmission circuit 30 side, an excitation signal is generated as described below and input to the bidirectional transmission circuit 30.

The feedback signal PR from the bidirectional transmission circuit 30 and the signal P corresponding to the blowing pressure are input to the subtracter Bl+. A signal PA corresponding to the air pressure applied to the reed of the mouthpiece portion is obtained from the subtracter B.

The signal PA is input to the low-pass filter 12, and
The signal is inverted by the multiplier INV and input to the multiplier M6. The low-pass filter 12 simulates the inertial delay of the lead, and high-frequency components of the signal PA are removed by passing it through the low-pass filter 12. In this way, the response characteristics of the reed to absorb sudden pressure changes are simulated.

Then, by the adder Ah+, the low-pass filter 12
The signal E corresponding to the unbundling is added to the output signal P of , and the signal P3 is obtained.

This signal P is then given to the ROM 15 as an address. As a result, a table of nonlinear functions stored in advance in the ROM 15 is referred to, and a signal Y corresponding to the cross-sectional area of the gap between the reed and the mouthpiece, that is, the admittance to the airflow is output. Then, the signal Y and the output signal -PA of the multiplier INV are multiplied by a multiplier M to obtain a signal FL corresponding to the flow velocity of air passing through the gap between the reed and the mouthpiece portion.

Then, the signal PL is multiplied by a multiplication coefficient G by a multiplier M (7). Here, the multiplication coefficient G is a constant determined according to the pipe diameter near the mouthpiece section in the resonance tube. , the difficulty of passing airflow, i.e.
It corresponds to the impedance to air flow.

Therefore, from the multiplier M17, a signal corresponding to the change in air pressure occurring at the mouthpiece side entrance of the resonance tube, that is, an excitation signal is obtained. This excitation signal is then manually input to the bidirectional transmission circuit 30 via the junction 20.

The bidirectional transmission circuit 30 is constructed by cascading multiple stages of four-terminal circuits Qj that simulate the propagation and scattering of air pressure waves in a resonant tube, and one stage is shown in FIG. . shift register S
Fs and SF simulate the propagation delay of the air pressure wave, as in the case of the four-terminal circuit shown in FIG. 9 described above. Further, A and A are adders, and B and B are subtracters. Further, FCl and FC are filters.

In the case of simulating a wind instrument having a tone hole, a 3-port wind instrument disclosed in Japanese Patent Application Laid-Open No. 63-40199 is inserted at a location corresponding to the tone hole position in the bidirectional transmission circuit 30.

The four-terminal circuit shown in FIG. 9 described above is equivalent to the configuration shown in FIG. In FIG. 2, M and M are multipliers that each multiply the input signal by a coefficient k.

The four-terminal circuit Qj shown in FIG. 1 includes the multipliers M and M in the configuration shown in FIG. 2, and the filter FC! and F.C.
, and the output from the last stage in shift register SF , N (N is an integer) before the end is input to filter PC3, and the output from the last stage in shift register SF 4 before N stages. The configuration has been changed so that the filter FC is inputted to the filter FC.

FIG. 3 shows an example of the configuration of filters FC5 and FC4. The input signal to the filter is input to one input terminal of adder A7. The output of adder A7 is sent to delay circuit D.
adder A, delayed by one sampling period by L,
The adder A7 and the delay circuit DL constitute an integrator. The output of the adder A7 and a signal obtained by delaying the output of the adder A7 by (2N+1) sampling periods by the delay circuit DL are input to the subtracter B, and subtraction between the two is performed.

Then, a multiplier M is applied to the output signal of the subtracter Bs.

The coefficient is multiplied by /(2N+1) and output as an output signal. The impulse response of this filter is
As shown in the figure. As shown in the figure, when an impulse is input to this filter in the 0th sampling period, from that point onwards for (2N+1) sampling periods, that is,
During the period from the Oth sampling period to the 2Nth sampling period, an output having a value of k/(2N+1) is obtained.

A low-pass filter ML is interposed between the output terminal T and the input terminal T of the bidirectional transmission circuit 30.

This low-pass filter ML simulates the frequency characteristics of acoustic loss imparted to musical tones at the terminal end of the resonance tube. In mixer MX, bidirectional transmission circuit 3
The signal at a predetermined node within 0 and the signal at the output terminal T1 are mixed and output as a musical tone signal.

The operation of this musical tone synthesis device will be explained below. Excitation circuit 1
The excitation signal generated by 0 is input to the bidirectional transmission circuit 30 via the junction 20. Within the bidirectional transmission circuit 30, the signal propagates through the cascade-connected four-terminal circuits Qj, Qj, . . . in the direction of arrow F, and is output from the output terminal T1.

Then, the sound at the end of the resonance tube is applied through the low-pass filter ML, and is re-inputted into the bidirectional transmission circuit 30 from the input terminal T. The signal is then propagated through the cascade-connected four-terminal circuits Qj, Qj, .

Here, the four-terminal circuit Qj1Qj in the bidirectional transmission circuit 30
The signal scattering performed in 1... will be explained. For example, assume that an impulse is output from the final stage of the shift register SF in the 0th sampling period.

In this case, since the impulse is input to the filter FC,l at a time N sampling periods before sor,
From that point on, for a period of (2N+1) sampling periods, an output of /(2N+1) is obtained from the filter PC. That is, as shown in FIG. 5, impulses are output from the shift register SF in the 0th sampling period, while impulses are output from the filter FC during the period from the (-N)th sampling period to the Nth sampling period. k/(
2N+1) is output. This also applies to the soft register SF and filter PC.

In this way, the signal propagating through the shift register 5Fff is dispersed in the time axis direction, and the coefficient is multiplied by /(2N+1) and input to adders A and A6, and the signal propagating through the shift register SF is distributed over time. The coefficients are distributed in the axial direction, multiplied by /(2N+1), and input to subtracters B and B6. As a result, the number of stages of foot registers SF3 and SF of the four-terminal circuit in FIG.
The circuit obtained by changing the coefficients of , and M to /(2N+1) and cascading (2N+1) stages of this four-terminal circuit can perform almost the same operation as the four-terminal circuit Qj in Figure 1. be exposed.

According to such a four-terminal circuit Qj, the propagation of air pressure waves within a cylinder whose tube diameter changes in an exponential curve can be faithfully simulated. By cascading a plurality of four-terminal circuits Qj, as shown in FIG. 6, it is possible to simulate the operation of a resonant tube having a shape similar to that seen in an actual natural musical instrument.

In this embodiment, the excitation signal is formed based on the input signal and the feedback signal, but the bidirectional transmission circuit is brought into a resonant state by injecting the input signal into the bidirectional transmission circuit. Good too. Further, the present invention can be used not only for synthesizing wind instrument sounds but also for synthesizing voices and the like.

Furthermore, in the above embodiments, the case where the musical tone synthesis device is realized by a digital circuit has been explained as an example, but it goes without saying that the present invention can be realized by an analog circuit.

The configurations of filters FCy and FC4 are not limited to the configuration shown in FIG. 3, but can also be easily realized using, for example, an FIR filter. Moreover, it may be realized not only by a circuit but also by a software program.

"Effects of the Invention" As explained above, according to the present invention, a filter that disperses an input signal to itself in the time axis direction and outputs the filter is connected to a predetermined position of the loop means, and the filter that outputs the signal dispersed in the time axis direction is connected to a predetermined position of the loop means. Since the signal is transmitted through the filter to the signal supply destination or reflected to the signal supply side, a resonant tube whose tube diameter is not constant can be faithfully simulated, and the scale of the device can be increased. The effect is that the musical tones of wind instruments can be synthesized faithfully.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a musical tone synthesizer according to an embodiment of the present invention, FIG. 3 is a diagram showing an example of the configuration of filters FC3 and FC4 in the same embodiment, and FIGS. 4 and 5 are diagrams showing the same implementation. Figure 6 is a diagram illustrating the impulse response of the example, Figure 6 is a diagram illustrating a resonance tube simulated by the same example, Figure 7 is a diagram illustrating a resonance tube of a wind instrument, and Figure 8 is an approximation of a resonance tube. FIG. 9 is a diagram showing a cylindrical connection structure, FIG. 9 is a diagram showing a four-terminal circuit used in a conventional musical tone synthesizer, and FIG. 2 is a diagram showing an equivalent circuit of the circuit in FIG. 9. IO...excitation circuit, 30...bidirectional transmission circuit, SF3 and SF,...-shift register,
PC, FC,...filter.

Claims (1)

[Scope of Claims] Comprised of an excitation means that generates an excitation signal based on an input signal, and a loop means that performs at least delay processing on the excitation signal and repeatedly circulates the excitation signal, and the excitation means and the loop means are arranged to resonate. In a musical tone synthesis device that generates a musical tone signal by changing the state, a filter that disperses the input signal to itself in the time axis direction and outputs the resultant signal is connected to a predetermined position of the loop means, and the signal arriving at the connected position is A musical tone synthesis device characterized in that the signal is transmitted through the filter to the signal supply destination, or is reflected to the signal supply side.