JP2722791B2 - Music synthesizer - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a musical sound synthesizer suitable for use in synthesizing musical sounds of natural musical instruments. 2. Description of the Related Art A musical sound synthesizer that synthesizes a natural musical instrument sound by operating a model simulating a sounding mechanism of a natural musical instrument is known. As a tone synthesizer for attenuated sound of a percussion instrument or a stringed instrument, a loop circuit including a delay circuit that simulates a propagation delay of vibration in a string and a filter that simulates acoustic loss in a string, and a loop circuit that includes a string Alternatively, there is known a so-called delayed feedback type tone synthesizer comprising an excitation circuit for inputting an excitation signal corresponding to an excitation vibration at the time of string striking. This kind of musical sound synthesizer is disclosed, for example, in Japanese Patent Publication No. 58-58679. Further, as a musical sound synthesizer for sustained sounds such as wind instruments, for example, a waveguide (bidirectional delay transmission path) simulating the propagation of an air pressure wave in the resonance pipe of a wind instrument
There is known a configuration in which a non-linear amplification element that simulates the operation of a lead for exciting an air pressure wave inside a resonance tube is combined. According to this configuration, the output signal of the nonlinear amplifying element is transmitted with the waveguide directed to the terminal, and the signal reflected at the terminal is returned to the nonlinear amplifying element via the waveguide in the reverse direction. The operation is repeated. That is, the operation of generating and reciprocating air pressure waves inside the actual wind instrument is faithfully simulated. Then, a desired tone signal is extracted from an arbitrary node in the waveguide. This type of technique is disclosed in Japanese Patent Application Laid-Open No. 63-40199. "Problems to be Solved by the Invention" By the way, there is a case where a demand arises to give a complex tone change to the tone signal synthesized as described above. In this case, the above requirement has been met by connecting a filter having a transfer function that can obtain a desired tone change to the output section of a delay feedback type tone synthesis device or a tone synthesis device using a waveguide. . However, when the change in tone color to be realized is complicated and subtle, it is necessary to prepare a higher-order filter, and there is a problem that the entire device becomes large-scale. SUMMARY OF THE INVENTION An object of the present invention is to provide a tone synthesizer having a complicated and subtle tone color adjustment function without increasing the scale of the apparatus. [Means for Solving the Problems] The present invention provides a delay unit including an n-stage (n is a natural number) delay element, a closed loop unit that connects at least the delay units in a closed loop, and a predetermined loop unit in the closed loop unit. Means for inputting an excitation signal to a node of the following, and for each output signal of successive m-stage (m is a natural number of 2 or more and n or less) among the n-stage delay elements of the delay means,
And a tone color adjusting means for multiplying each by a multiplication coefficient corresponding to a desired filter operation, adding the multiplication results, and outputting the addition result as a tone signal without feeding back the addition result to the closed loop means. And [Operation] According to the above configuration, the circulation of the input excitation signal is repeated in the closed loop means. Then, of the n delay elements of the delay means in the closed loop means, each output signal of m successive delay elements (m is a natural number of 2 or more and n or less) is extracted, and a filter is applied to each signal. After being multiplied by the calculation coefficient and the result of each multiplication being added, the result is output as a tone signal without being fed back to the closed loop means. As a result, it is possible to share the means for performing the delay processing in the operation of the filter for giving a complex change to the tone color of the synthesized tone signal and the means for performing the delay processing in the closed loop means. Further, even if the filter characteristic is changed, the characteristic of the signal returning to the closed loop means does not change, so that the characteristic of the output tone signal can be changed without changing the characteristic of the signal circulating through the closed loop means. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[Principle of the present invention]

FIG. 1 is a block diagram illustrating the principle of the present invention. 1 is a delayed feedback type tone formation portion, each having a delay time of one sampling period, multiplies the n delay elements D ₁ -Dn cascaded filter for acoustic loss causing the damping coefficient A signal processing circuit 2 including a coefficient multiplier, a delay circuit for pitch adjustment, and the like, and an adder 3 are connected in a closed loop. Then, the waveform generating circuit 4 generates an initial waveform including many frequency components such as an impulse waveform, and the initial waveform is introduced from the adder 3 into the delay feedback type tone synthesizer 1 and circulates in the loop. As a result, a damping sound is formed. Output signal and the output signal of the delay element D ₁ -Dn adder 3 are each provided to a multiplier M ₀ to Mn, the desired coefficients a ₀ .about.An corresponding to filter operation is multiplied. Then, these multiplication results are added by the adder 5,
The addition result is output as a tone signal. Here, assuming that the transfer function of the signal processing circuit 2 is F (z), the transfer function between the waveform X supplied from the waveform generator 4 and the tone signal waveform Y obtained from the adder 5 is represented by the following equation ( It becomes like 1). As shown in the above equation (1), the transfer function of the configuration of FIG.
1 / (1-z- ^nF ) and nth-order FIR (finite impulse response)
Filter transfer function Are combined. That is, a transfer function completely equivalent to the case where an FIR filter is separately connected to the delay feedback type tone synthesizer 1 is realized. As described above, since the means for performing the delay processing required for the filter operation and the means for performing the delay processing in the closed loop means are shared, it is possible to perform complicated and subtle tone adjustment without increasing the scale of the apparatus. Can be.

First Embodiment FIG. 2 shows an example of a configuration in which the present invention is applied to a musical tone synthesizer for attenuated sounds such as pianos and guitars. In this figure, parts corresponding to those in FIG. 1 described above are denoted by the same reference numerals, and description thereof will be omitted. This musical tone synthesizer is supplied with a key-on signal KON generated by operating a performance operator (for example, a keyboard or the like) (not shown) and pitch information PITCH for specifying a pitch to be sounded. In FIG. 2, the variable delay circuit 14 includes a shift register and a selector 6 in which delay elements DD _{1 to} DDm having a delay time of one sampling period are cascaded. The output of the delay element Dn are input to the delay element DD ₁ of the first stage of the variable delay circuit 14, the delayed output of the delay element DD ₁ ～DDm is inputted to the selector 6. Then, the delay control information corresponding to the pitch information PITCH is generated by the coefficient control unit 7, and the integer part k is given to the selector 6 as select information. As a result, the delay output corresponding to the k from among the delayed output of the delay element DDZ ₁ ~DDm is selected and output. That is, if one sampling period is τ, the output of the delay element Dn is delayed by kτ and
And sent to the variable delay circuit 15. In the case of this embodiment, since the delay elements D _{1 to} Dn are interposed as fixed delay circuits, the total delay time of the delay elements D _{1 to} Dn is subtracted from the reciprocal of the tone frequency corresponding to the pitch information PITCH. The delay time is specified by the delay specification information. In the variable delay circuit 15, the output signal from the selector 6 is input to the multiplier 10, and is input to the multiplier 9 after being delayed by one sampling period by the delay element 8. These multipliers 9 and 10 are provided with fractional parts b and 1-b of the delay designation information as multiplication coefficients, respectively. Then, the outputs of the multipliers 9 and 10 are added by the adder 11 and output. According to the variable delay circuit 15, linear interpolation of two signals input before and after one sampling period is performed, and the signal input to the delay circuit 8 is effectively delayed by bτ and output from the adder 11. Is done. Each frequency component of the output signal of the adder 11 is attenuated according to the filter characteristics of the low-pass filter 12. Then, the output signal of the low-pass filter 12 is multiplied by an attenuation coefficient γ determined according to a desired attenuation envelope by the multiplier 13, and the multiplication result is fed back to the adder 3. The waveform generator 4a is, for example, a ROM (read only memory)
And a sample sequence of waveform values of the initial waveform is stored. In consideration of the stability of timbre control and pitch control, it is desirable to change the frequency of the initial waveform according to the pitch of a musical tone to be generated. Therefore, the entire range to be generated is divided into, for example, octave units, and an initial waveform having an optimum frequency is stored for each division obtained by the division. In such a configuration, when the performance operator is operated to generate the key-on signal KON and the pitch information PITCH, the initial waveform corresponding to the pitch information PITCH is read from the waveform generator 4a. Then, this read waveform is introduced into a closed loop consisting of an adder 3 → delay circuits D _{1 to} Dn → variable delay circuit 14 → variable delay circuit 15 → low pass filter 12 → multiplier 13, and thereafter attenuates in the closed loop while attenuating. Circulate. Then, the output signal of the adder 3 and each of the delay outputs of the delay elements D _{1 to} Dn are multiplied by coefficients a _{0 to} an for the filter operation,
Each multiplication result is added and output as a tone signal.

Second Embodiment FIG. 3 shows an example of the configuration when the present invention is applied to a clarinet tone synthesizer. In the figure, an excitation circuit 20 corresponds to a mouthpiece portion of a clarinet, and a resonance circuit 40 corresponds to a resonance tube of the clarinet. The junction 36 inserted between the excitation circuit 20 and the resonance circuit 40 simulates the scattering of the air pressure wave at the connection between the mouthpiece and the resonance tube. In this junction 30, the resonance circuit
The output signal from 40 and the output signal of the excitation circuit 20 are added by the adder 31 and input to the resonance circuit 40, and the output signal of the adder 31 and the output signal of the resonance circuit 40 are added by the adder 32 and the excitation circuit 20 is to be entered. The excitation circuit 20 includes an attenuator 21, filters 22 and 23, an adder 24, a ROM 25, multipliers 26 and 27, and INV.
When a musical tone is generated, a signal P for designating the blowing pressure and a signal E for designating embouchure (pressure when the mouthpiece is held in the mouth) are given from the coefficient control unit 50. The subtractor 21 has a signal PR input from the resonance circuit 40 through the junction 30, that is, a signal PR corresponding to the air pressure of the air pressure wave that is reflected in the resonance pipe or at the end of the resonance pipe and arrives at the mouthpiece. , A signal P corresponding to the blowing pressure is input. Then, the signal P is subtracted from the signal PR by the subtractor 21 to obtain a signal PA corresponding to the air pressure applied to the clarinet lead. The output signal PA of the subtractor 21 is band-limited by the filter 22. The filter 22 is constituted by a first-order low-pass filter, and is inserted so as to prevent the amplitude of a signal circulating between the excitation circuit 20 and the resonance circuit 40 from becoming extremely large at a characteristic frequency. The output signal P ₁ of the filter 22 is input to the filter 23, is inputted are inverted to the multiplier 26 by a multiplier INV. Signal P ₁ by the intervention of the filter 23, the high frequency component is removed. This simulates the response characteristics of a lead that absorbs sudden pressure changes. Then, the output signal P _{2 of the} filter 23 is output by the adder 24.
To, is added to the signal E corresponding to Enbushua, the signal P ₃ are determined corresponding to the actual pressure applied to the lead. This signal P ₃ is supplied as an address to the ROM 25. 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. And the signal Y
The signal -P ₁ and are multiplied by a multiplier 26, a signal FL is obtained, which corresponds to the flow rate of air passing through the gap between the mouthpiece and reed unit. The multiplier 27 multiplies the signal FL by a multiplier coefficient G
Is multiplied. Here, the multiplication coefficient G is a constant determined according to the pipe diameter in the vicinity of the mouthpiece mounting portion of the resonance pipe, and corresponds to the difficulty of the air flow, that is, the impedance to the air flow. Therefore, a signal corresponding to a change in pressure of air generated at the mouthpiece-side entrance of the resonance tube is obtained from the multiplier 27. Then, this signal is input to the resonance circuit 40 via the junction 30. In the resonant circuit 40, the delay element D ₁ -Dn, delay caused when the air pressure wave round trip between the lead, the first tone hole in the resonance tube (sound hole) is simulated. Junction JU ₁ is obtained by simulating the scattering of the air pressure wave in the vicinity of the first tone hole counted from the lead side, in this embodiment, the multiplier MJ ₁
, MJ ₄ , and a 4-multiplier lattice composed of adders AJ ₁ and AJ ₂ . Here, in the multipliers MJ _{1 to} MJ ₄ , multiplication coefficients k ₁ , k ₁ , 1−k ₁ , −k ₁ determined according to the open / closed state of the target tone hole are respectively controlled by the coefficient control unit 50. Given. The subsequent stage of the junctions JU _1, the delay circuit DL ₁ ~DLl having a delay time corresponding to the length between the tone hole in the resonance tube, are cascade-connected via the junction equivalent structure as junctions JU ₁ (Not shown). The output of the delay circuit DLl in the final stage is band-limited by the low-pass filter 41, is further multiplied by the negative coefficient δ by the multiplier 42, reverses the cascade-connected junction, and further excites through the junction 30. The signal is fed back to the subtracter 21 of the circuit 20. In such a configuration, when an operation element (not shown) is operated to give an instruction to generate a musical tone, a signal corresponding to the blowing pressure P and the embouchure E is generated by the coefficient control section 50 and supplied to the excitation circuit 20. In addition, corresponding to the opening / closing state of each tone hole, the coefficient multiplication coefficients k ₁ , k ₁ , 1−k ₁ , −k ₁ , −k ₁ , of the junction (JU ₁ and the subsequent unillustrated junction) corresponding to each tone hole. kl, kl, 1−k
l and -kl are determined and supplied to the respective junctions. Then, an excitation signal based on the blowing pressure P and the embouchure E is output from the excitation circuit 20. This signal is input to the resonance circuit 40 via the junction 30. The signal input via the junction 30 is
And is returned to the excitation circuit 20 via the junction 30 again. In the excitation circuit 20, the signal returned from the resonance circuit 40 and the blowing pressure P
The signal processing described above is performed on the basis of the embouchure E and the new excitation signal is input to the resonance circuit 40 via the junction 30. Hereinafter, the same operation is performed, and the excitation circuit
A signal is circulated between 20 and the resonance circuit 40. Then, for each delayed output of the input signal of the delay element D ₁ in the resonant circuit 40 and a delay element D ₁ -Dn, multipliers M ₀ to Mn
Are multiplied by the coefficients a _{0 to} an for the filter operation, and the multiplication results are added by the adder 5 and output as a tone signal. In the above embodiment, an example is described in which one FIR filter for tone color adjustment is provided in the tone synthesizer, but it may be provided at a plurality of locations. In this case, the outputs of a plurality of FIR filters may be mixed and output. Also FI
The number of stages of the delay circuit shared with the closed loop means (the delay feedback type tone generator and the resonance circuit in the above embodiment) to constitute the R filter corresponds to the required order of the filter operation and can be determined arbitrarily. . Also, when the frequency of the generated musical tone is high, it may be difficult to reduce the total delay time of the closed loop means accordingly. However, in this case, by reducing the order of the filter operation and reducing the number of stages of the delay circuit used as the FIR filter, it is possible to make the total delay time of the closed loop means a value suitable for a desired pitch. [Effects of the Invention] As described above, according to the present invention, the delay means including delay elements of n stages (n is a natural number), the closed loop means connecting at least the delay means in a closed loop, A means for inputting an excitation signal to a predetermined node in the closed loop means; and an output signal of m successive delay elements (m is a natural number of 2 or more and n or less) among n delay elements of the delay means. On the other hand, a timbre adjusting means for multiplying by a multiplication coefficient corresponding to a desired filter operation, adding the multiplication results, and outputting the addition result as a tone signal without returning the addition result to the closed loop means is provided. Therefore, the means for performing the delay processing in the filter operation for imparting a complex change to the tone color of the synthesized tone signal and the means for performing the delay processing in the closed loop means are shared It can, without increasing the size of the apparatus,
There is an effect that a tone synthesis device capable of performing complicated and subtle tone adjustment cannot be realized. Also,
Even if the filter characteristics are changed, the characteristics of the signal circulating in the closed loop means do not change, so that the characteristics of the output tone signal can be changed without changing the characteristics of the signal circulating in the closed loop means. In addition, the change in the frequency characteristic of the filter and the change in the characteristic of the generated tone signal uniquely correspond to each other, so that a tone signal having desired characteristics can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a basic configuration of the present invention, FIG. 2 is a block diagram showing a configuration of a musical tone synthesizer according to a first embodiment of the present invention, and FIG. 3 is a musical tone according to a second embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a synthesis device. 1 ...... delayed feedback type tone formation portion, D ₁ -Dn ...... 1
Sampling period delay elements, M ₀ to Mn ...... multiplier, 5 ......
Adder.

Claims (1)

(57) [Claims] 1. A delay means comprising delay elements of n stages (n is a natural number); a closed loop means connecting at least the delay means in a closed loop; and an excitation signal inputted to a predetermined node in the closed loop means. Multiplying each output signal of successive m-stage delay elements (m is a natural number not less than 2 and not more than n) among the n-stage delay elements of the delay means. A tone synthesizer comprising: multiplying a coefficient; adding a result of the multiplication; and outputting the added result as a tone signal without feeding back the result to the closed loop means.