JP2808793B2 - Music synthesizer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a musical sound synthesizer suitable for use in synthesizing wind instrument sounds and voices.

2. Description of the Related Art There is known a method of operating a model obtained by simulating a sounding mechanism of a natural musical instrument, thereby synthesizing a musical tone of the natural musical instrument. As a most basic model of a wind instrument, a model having a structure in which a non-linear amplification element simulating the elastic characteristic of a lead and a bidirectional transmission circuit simulating a resonance tube are connected is known. In this model, when a signal is output from the non-linear amplifier, the signal is input to the bidirectional transmission circuit as a traveling wave signal, and is reflected at the end of the bidirectional transmission circuit. , Is fed back to the nonlinear amplification element. Then, when the nonlinear amplification element and the bidirectional transmission circuit are brought into a resonance state, a synthetic sound of the wind instrument is generated.

In general, the diameter of a resonance tube of a wind instrument is not constant. For example, the diameter of a resonance tube of a trumpet or the like increases toward the end as illustrated in FIG. Here, since the pipe diameter affects the admittance to the air pressure wave, in the resonance pipe as shown in FIG. 7, scattering based on the change of the admittance occurs in each part in the pipe. Then, as a result of the scattering of the air pressure wave corresponding to the tube shape in the resonance tube, a musical tone having a tone color 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. Such a structure can be simulated by cascading a two-input two-output four-terminal circuit as shown in FIG.

In FIG. 9, SF ₃ and SF ₄ are shift registers that simulate the propagation delay of the air pressure wave in cylinders # 3 and # 4, respectively. Also, A ₃ and A ₄ are adders, M ₁ ~M ₄ is a multiplier. 1+ attached to multipliers M _{1 to} M ₄
k, -k, 1-k, and k are multiplication coefficients. Cylinder # 3
When the cross-sectional area of S _3, the cross-sectional area of the cylindrical # 4 is assumed to be S _4,
The value of k is determined by the following equation (1).

From the shift register SF ₃ signal corresponding to the air pressure wave incident on the coupling surface T ₃₄ the cylindrical # 4 propagates through the cylindrical # 3 is output. The coefficient (1 + k) is multiplied by the output signal of the shift register SF ₃ by the multiplier M _1. The result of this multiplication, the signal corresponding to the air pressure wave that propagates in cylindrical # 4 is transmitted through the coupling surface T ₃₄ is obtained, this signal via an adder A _4, the shift register SF of the next 4-terminal circuit It is input to a circuit (not shown) corresponding to ₃ . The coefficient k by the multiplier M ₂ to the output signal of the shift register SF ₃ is multiplied. The result of this multiplication, the signal corresponding to the air pressure wave is reflected at the connecting surface T ₃₄ is obtained, the signal adder
Through A _3, it is input to the shift register SF ₄ equivalent circuit of 4-terminal circuit of the preceding stage (not shown).

Same processing for the output signal of the shift register SF ₄ it is carried out, together with a signal corresponding to the air pressure wave which passes through the cylinder # 3 side from the connecting surface T ₃₄ by the multiplier M ₄ is output, the multiplier M ₃ As a result, a signal corresponding to the air pressure wave reflected from the connection surface _T34 toward the cylinder # 4 is output. The same operation as described above is performed also in the four-terminal circuits in the preceding and subsequent stages of the four-terminal circuit in FIG. According to such a cascade-connected circuit, it is possible to simulate the propagation of the air pressure wave in the case of the tube shape shown in FIG. 8, and to approximate the resonance tube of a natural instrument as shown in FIG. Can be simulated. This type of technology is disclosed in, for example,
No. -40199.

"Problems to be Solved by the Invention" By the way, in the conventional tone synthesizer, in order to faithfully reproduce the timbre of the wind instrument, it was necessary to provide a large number of four-terminal circuits shown in FIG. For this reason, there has been a problem that the musical tone synthesizer becomes large-scale. Further, in the case of performing musical tone synthesis by arithmetic processing such as a DSP (Digital Signal Processor), there is a problem that the amount of computation increases and real-time musical tone synthesis becomes difficult.

The present invention has been made in view of the above-described circumstances, and can simulate the scattering of air pressure waves in a resonance tube faithfully without increasing the scale of the device, and can produce musical sounds having a tone close to that of a natural musical instrument. It is an object of the present invention to provide a musical sound synthesizer capable of synthesizing.

"Means for Solving the Problems" The present invention comprises means for generating an excitation signal based on an input signal, and loop means in which delay means are connected in a closed loop, and the excitation signal is input to the loop means. A sound signal synthesizing device configured to output a circulating signal circulating through the loop means as a musical sound signal, wherein a circulating signal of the loop means is input, and a filter for filtering and outputting the circulating signal; Synthesizing means interposed in a closed loop for synthesizing a signal output from the filter with a circulating signal of the loop means, wherein the synthesizing means synthesizes a signal output from the filter. The circulating signal after a predetermined time period is input to the filter.

Further, in the present invention, the loop means has a forward path and a return path, and the synthesizing means is inserted into each of the forward path and the return path and receives a signal output from the filter. It is characterized by being.

[Operation] According to the above configuration, at a predetermined position of the loop means,
The circulating signal at a predetermined time later than the circulating signal at which the signal output from the filter is combined is input to the filter. Therefore, signal processing equivalent to the case where signal reflection and transmission are performed at a plurality of continuous nodes including the connection position of the filter is performed.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of a musical sound synthesizer according to an embodiment of the present invention. In the figure, reference numeral 10 denotes an excitation circuit simulating a mouthpiece of a wind instrument, and reference numeral 30 denotes a bidirectional transmission circuit simulating a resonance tube. Also,
The junction 20 inserted between the excitation circuit 10 and the resonance circuit 30 simulates the scattering of air pressure waves at the connection between the mouthpiece and the resonance tube. This junction 20 and summed by the output signal adder A ₁₈ of the output signal and the excitation circuit 10 from the bidirectional transmission circuit 30 is inputted to the bidirectional transmission circuit 30, the output signal of the adder A ₁₈ and bidirectional transmission are input to the excitation circuit 10 the output signal of the circuit 30 is added by the adder a _19.

The excitation circuit 10 includes a subtractor B ₁₁ , a low-pass filter 12, an adder A ₁₄ , a ROM (read only memory) 15, a multiplier M ₁₆ , M
₁₇ and INV. When a musical tone is generated, the excitation circuit 10 supplies a blowing pressure P,
Information corresponding to embouchure E (an amount inversely proportional to the pressure at which the mouthpiece is held in the mouth) is provided. Then, this information and the feedback signal from the bidirectional transmission circuit 30 side
An excitation signal is generated based on the PR as described below, and is input to the bidirectional transmission circuit 30.

A subtractor B ₁₁ is the feedback signal PR from the bi-directional transmission circuit 30
Then, a signal P corresponding to the blowing pressure is input. Then, the signal PA is obtained which corresponds to the air pressure applied from the subtractor B ₁₁ in the mouthpiece portion of the lead.

Signal PA is is inputted to the low-pass filter 12 are input is inverted to the multiplier M ₁₆ by a multiplier INV. The low-pass filter 12 simulates an inertial delay of a lead and the like, and the high-frequency component of the signal PA is removed by passing through the low-pass filter 12. In this way,
The response characteristics of a lead that absorbs sudden pressure changes are simulated.

Then, the adder A ₁₄ adds the signal E corresponding to the embouchure to the output signal P ₂ of the low-pass filter 12 to obtain the signal P ₃ . Then, the signal P ₃ is ROM1
Given to 5 as an address. As a result, the table of the non-linear function stored in the ROM 15 is referred to, and the signal Y corresponding to the cross-sectional area of the gap between the lead and the mouthpiece, that is, the admittance to the air flow is output. Then, an output signal -PA multiplier INV signal Y is multiplied by the multiplier M _16, the signal FL is obtained, which corresponds to the flow rate of air passing through the gap between the mouthpiece and reed unit.

Then, with respect to signals FL, multiplication coefficient G is multiplied by the multiplier M _17. Here, the multiplication coefficient G is a constant determined according to the diameter of the tube near the mouthpiece mounting portion of the resonance tube, and corresponds to the difficulty in passing the airflow, that is, the impedance to the airflow. Therefore, the multiplier M _17, the signal corresponding to the pressure change of air generated at the mouthpiece side of the inlet of the resonance tube, i.e., the excitation signal is obtained. Then, the excitation signal is input to the bidirectional transmission circuit 30 via the junction 20.

The bidirectional transmission circuit 30 is configured by cascading a plurality of four-terminal circuits Qj simulating the propagation and scattering of air pressure waves in a resonance tube, and FIG. 1 shows one stage thereof. . Shift register SF ₃ and SF _4, as with the four-terminal circuit in FIG. 9 described above,
This simulates the propagation delay of the air pressure wave.
Moreover, A ₅ and A ₆ are adders, B ₅ and B ₆ are subtractor (adders A _5, A _6, subtractor B _5, B _6, and the shift register SF _3, SF ₄ synthetic means Make). FC ₃ and FC ₄ are filters. When simulating a wind instrument having a tone hole, a three-port junction disclosed in Japanese Patent Application Laid-Open No. 63-40199 is inserted at a position corresponding to the position of the tone hole in the bidirectional transmission circuit 30.

The aforementioned four-terminal circuit of FIG. 9 is equivalent to the configuration shown in FIG. In Figure 2, M ₅ and M ₆ are multipliers for multiplying each coefficient k to the input signal. 4-terminal circuit Qj illustrated in FIG. 1, the multipliers M ₅ and M ₆ in the configuration of Figure 2 has been replaced by a filter FC ₃ and FC _4, from the last stage of the shift register SF ₃ N (N Integer) The previous output is input to the filter FC ₃ and the shift register SF ₄
Configured such that the output of the previous N-stage is input to the filter FC ₄ is changed from the last stage in the.

FIG. 3 shows a configuration example of a filter FC ₃ and FC _4. Input signal to the filter is input to one input terminal of the adder A _7. The output of the adder A ₇ is adapted to be inputted to the other input terminal of the adder A ₇ is one sampling period delay by the delay circuit DL _1, adder A ₇ and the delay circuit
The DL ₁ and the integrator constitute. A subtractor B ₈ receives the output of the adder A _7, the delay circuit DL ₂ the output of the adder A ₇ (2N + 1) signal are obtained by sampling period delay is entered, both the subtraction is performed. Then, with respect to the output signal of the subtracter B _8, the coefficient by the multiplier _{M 9 k / (2N + 1} ) are multiplied, is output as an output signal. FIG. 4 shows the impulse response of this filter. As shown in the drawing, when an impulse is input to this filter in the 0th sampling period, the time period is (2N + 1) sample periods, that is, the period from the 0th sampling period to the 2Nth sampling period, k / ( 2N + 1) is obtained.

Low pass filter ML is interposed between the output value T ₁ and the input terminal T ₂ of the two-way transmission circuit 30. This low-pass filter ML simulates the frequency characteristics of acoustic loss applied to a musical tone at the end of the resonance tube. In the mixer MX, signal and is mixed in the signal and the output terminal T ₁ of the predetermined node of the bidirectional transmission circuit 30, is outputted as the musical tone signal.

Hereinafter, the operation of the tone synthesizer will be described. Excitation circuit
The excitation signal generated by 10 is input to the bidirectional transmission circuit 30 via the junction 20. Bidirectional transmission circuit 30
Within, the signal is a cascaded four-terminal circuit Q
j, Qj, propagate ... in the direction of arrow F, is output from the output terminal T _1. The acoustic resonance tube end portion is given by the intervention of a low-pass filter ML, it is re-entered from the input terminal T ₂ to the bidirectional transmission circuit 30. The cascaded four-terminal circuits Qj, Qj,... Propagate in the direction of arrow R, and are returned to the excitation circuit 10 via the junction 20 as the feedback signal PR.

Here, the four-terminal circuits Qj, Qj,.
A description will be given of signal scattering performed in the above. In example zeroth sampling period, and the last stage of the shift register SF ₃ impulse is outputted. in this case,
The filter FC ₃ at the time N sampling cycles earlier than that
Since the impulse has been entered in (2N
+1) sampling cycle period, from the filter FC ₃ k / (2
N + 1) is obtained. That is, as shown in FIG.
The impulse is output from SF ₃ while the filter FC ₃
Output a signal of k / (2N + 1) during the period from the (-N) th sampling period to the Nth sampling period. The same applies to the case of the shift register SF ₄ and the filter FC _4.

Signals propagating in this manner the shift register SF ₃ are dispersed in the time axis direction, and the coefficient k / (2N + 1) is input to the adder A ₅ and A ₆ are multiplied, signal propagating shift register SF ₄ Is distributed in the time axis direction and the coefficient k /
(2N + 1) is input to the subtractor B ₅ and B ₆ are multiplied. As a result, the shift register SF ₃ of the four-terminal circuit shown in FIG.
And the number of stages of SF ₄ is 1, and the coefficients of multipliers M ₅ and M ₆ are k / (2
N + 1), and the operation almost equivalent to the circuit obtained by cascading the four-terminal circuit in (2N + 1) stages is the first.
This is performed by the four-terminal circuit Qj in FIG.

According to such a four-terminal circuit Qj, the propagation of an air pressure wave in a cylinder whose pipe diameter changes along an exponential function curve is faithfully simulated. By cascading the four-terminal circuit Qj in a plurality of stages, as shown in FIG. 6, it is possible to simulate the operation of a resonance tube having a shape close 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. However, the input signal is simply injected into the bidirectional transmission circuit so that the bidirectional transmission circuit is in a resonance state. Is also good. Further, the present invention can be used not only for synthesis of wind instrument sounds but also for synthesis of voices and the like.

Further, in the above embodiment, the case where the musical sound synthesizer is realized by a digital circuit has been described as an example, but it goes without saying that the present invention can be realized by an analog circuit. The configuration of the filter FC ₃ and FC ₄ is not limited to the configuration of FIG. 3, it is possible to easily realized by, for example, FIR filters. Further, it may be realized not only by a circuit but also by a software program.

[Effects of the Invention] As described above, according to the present invention, a circulating signal of a loop unit is input, and a filter that filters and outputs the circulating signal, and is inserted into a closed loop of the loop unit, Synthesizing means for synthesizing the signal output from the filter with the circulating signal of the loop means, wherein the synthesizing means performs the circulating after a predetermined time from the circulating signal in which the signal output from the filter is synthesized. Since the signal is input to the filter, the resonance tube having a non-constant tube diameter is faithfully simulated, and the effect that the tone of the wind instrument can be faithfully synthesized without increasing the scale of the device is obtained. Can be

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of a tone synthesizer according to an embodiment of the present invention, and FIG. 3 is a filter in the embodiment.
FIGS. 4 and 5 are diagrams illustrating an example of the configuration of FC ₃ and FC ₄ , FIGS. 4 and 5 are diagrams illustrating an impulse response of the embodiment, FIG. 6 is a diagram illustrating a resonance tube simulated by the embodiment,
FIG. 7 is a diagram illustrating a resonance tube of a wind instrument, FIG. 8 is a diagram showing a cylindrical connection structure approximating the resonance tube, FIG. 9 is a diagram showing a four-terminal circuit used in a conventional tone synthesizer, 2
The figure shows an equivalent circuit of the circuit of FIG. 10 Excitation circuit, 30 Bidirectional transmission circuit, SF ₃ and SF ₄
... shift registers, FC ₃ and FC ₄ ... filters.

Claims (2)

(57) [Claims] 1. An excitation means for generating an excitation signal based on an input signal, and a loop means in which delay means are connected in a closed loop, wherein the excitation signal is input to the loop means and the loop means is circulated. A sound signal synthesizer configured to output a circulating signal to be output as a sound signal, wherein a circulating signal of the loop means is input, and a filter for filtering and outputting the circulating signal is interposed in a closed loop of the loop means; Synthesizing means for synthesizing the signal output from the filter with the circulating signal of the loop means, wherein the synthesizing means is configured so that the signal output from the filter is synthesized a predetermined time later than the circulating signal synthesized. A tone synthesizer characterized by inputting a circulating signal to the filter. 2. The loop means has a forward path and a return path, and the synthesizing means is inserted into each of the forward path and the return path and receives a signal output from the filter. 2. The musical tone synthesizer according to claim 1, wherein: