JP3599978B2 - Tone signal forming device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a tone signal forming apparatus, and more particularly to a tone signal forming apparatus in which a physical structure of a musical instrument is modeled by circulating a signal in a waveform memory.
[0002]
[Prior art]
Conventionally, the present invention relates to a musical tone signal forming device for an electronic musical instrument in which a signal in a waveform memory is circulated to model a physical structure of a stringed musical instrument, that is, a musical tone signal forming device for an electronic musical instrument that repeatedly reads one cycle of a waveform. Various techniques have been proposed. One of such proposals is disclosed in, for example, Japanese Patent Application Laid-Open No. 49-131115 (first prior art). In this publication, a delay circuit and an all-pass filter are connected in a loop to change the phase, thereby realizing non-harmonicity of a musical tone.
[0003]
Further, as other proposals, there are those disclosed in, for example, JP-A-3-58094 and JP-A-5-66778 (second prior art). These gazettes disclose a technique for modeling a physical structure of a musical instrument in a pseudo tone signal forming apparatus of an electronic musical instrument by using a non-linear transformation. According to these proposals, there is an advantage that a portion having a complicated circuit configuration of a musical tone signal forming device of an electronic musical instrument can be realized with a simple configuration, or a portion whose circuit configuration has not been elucidated can be realized. ing.
[0004]
[Problems to be solved by the invention]
However, according to the above-mentioned first prior art, the inharmonicity of the musical tone can be realized, but the circuit configuration is complicated. Further, the second prior art can model the physical structure of a stringed instrument such as a piano, a harpsichord, a guitar, a harp, etc., but sufficiently realizes the inharmonicity of the sound emitted from the stringed instrument. I can't.
[0005]
SUMMARY OF THE INVENTION An object of the present invention has been made in view of the above-mentioned prior art, and realizes inharmonicity of stringed instrument sounds such as piano, harpsichord, guitar, and harp with a simple configuration, and a stringed instrument utilizing nonlinear transformation. It is an object of the present invention to provide a musical tone signal forming device for an electronic musical instrument, which can simultaneously realize the pseudo modeling of the structure of the electronic musical instrument. In other words, with a simple circuit configuration, an electronic device capable of simultaneously realizing both the inharmonicity of the musical tone of the first prior art and the modeling of the physical structure of a stringed instrument of the second prior art. An object of the present invention is to provide a musical tone signal forming device for a musical instrument.
[0006]
[Means for Solving the Problems]
In order to achieve the above object, according to the present invention, in a musical tone signal forming apparatus for modeling a physical structure of a musical instrument by circulating a waveform signal, a difference value of data at a plurality of positions of the waveform shape of the waveform signal is obtained. Means, nonlinear conversion means for nonlinearly converting and outputting the difference value obtained by the means, and addition means for adding data output from the nonlinear conversion means to a predetermined location between a plurality of locations of the waveform shape. There is a first feature in the provision.
[0007]
The present invention has a second feature in that the non-linear conversion means is provided with non-linear conversion data obtained by combining a trigonometric function and a linear function.
[0008]
ADVANTAGE OF THE INVENTION According to this invention, realization of the inharmonicity which string instrument sounds, such as a piano, a guitar, a harpsichord, and a harp, and pseudo modeling of the structure of a string instrument using a non-linear transformation are simultaneously implement | achieved with a simple structure. Can be.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 2 is a block diagram showing a schematic configuration of an electronic musical instrument to which the present invention is applied. The storage device 1 in FIG. 2 stores an excitation waveform, a non-linear conversion table, a system control program, and the like, and is also used as a work area for various calculations. Here, the excitation waveform means data representing the frequency envelope of each musical tone, and is usually equivalent to one cycle of musical tone waveform data.
[0010]
Next, the oscillation device 2 is a device for synthesizing a waveform that is a source of a musical tone, and is a device to which the present invention is applied. Embodiments of the oscillation device 2 will become clear from the description below. The timbre control filter 3 is a device that changes the timbre by controlling the frequency characteristics of a musical tone. The amplitude control device 4 is a device that controls the amplitude of the waveform to control the volume and envelope of the musical sound. The input device 5 corresponds to a device for inputting performance information such as a keyboard, a pedal, a switch, and a volume, and a MIDI (MIDI) input device.
[0011]
The central processing unit 6 is a device that controls a system by a system control program or the like stored in the storage device 1 or obtains parameters necessary for operating each peripheral device. The audio system 7 includes a D / A converter, an amplifier, a speaker, and the like, and is a device that converts a tone signal into sound. The bus 8 is composed of an address common bus and a data common bus, and transmits addresses and data passing between the devices.
[0012]
Next, an embodiment of the oscillation device 2 will be described with reference to the block diagram of FIG. The transmitting device 2 includes an n-stage (n is a positive integer) delay element 21 that receives an excitation signal and a cyclic signal, and one-stage delay elements 22 and 23 that are sequentially connected to the n-stage delay element 21. A subtractor 24 for subtracting an output signal of the one-stage delay element 23 from an output signal of the n-stage delay element 21; an output signal of the subtractor 24 as an input; It comprises a non-linear table 25 and an adder 26 which adds the output from the non-linear table 25 to the output of the one-stage delay element 22 and outputs the result to the one-stage delay element 23. The delay elements 21 to 23 can be realized by using a rewritable storage device.
[0013]
The excitation signal input to the n-stage delay element 21 is n-word waveform data representing a frequency envelope unique to a musical tone at the start of sound generation. This data is obtained by converting the frequency envelope of the musical tone into n-word discrete information. It can be obtained by inverse Fourier transform.
[0014]
As the non-linear table 25, a non-linear table having a sine wave characteristic as shown in FIG. As another example of the non-linear table 25, the table shown in FIG. 7A is added to a table of a linear function equivalent to multiplying the coefficient shown in FIG. c) The following table can be used. In the table (a), a sine wave is used. Alternatively, a triangular function wave having a different cycle may be added and synthesized with a desired amplitude.
[0015]
Next, the operation of the oscillation device 2 of the present embodiment will be described. When the excitation signal is input to the n-stage delay element 21, the excitation signal is delayed by the n-stage delay element 21 and output. The output from the delay element 21 proceeds to the delay element 22, and is added to the signal from the non-linear table 25 by the adder 26, and then proceeds to the delay element 23. On the other hand, the output signal of the delay element 21 and the output signal of the delay element 23 are input to the subtractor 24, and the subtracter 24 subtracts the output signal of the delay element 23 from the output signal of the delay element 21. Therefore, the subtractor 24 sequentially obtains a value representing a difference value between the two data points of the excitation signal waveform, in other words, a value representing the slope of the excitation signal waveform. The value representing the slope is input to the non-linear table 25, and is non-linearly converted by the table as shown in FIG. 3 (a) or (c). The output signal subjected to the non-linear conversion is input to the adder 26, and is added to the output signal from the delay element 22. The signal after the addition is fed back to the input side of the delay element 21 via the delay element 23, and enters the delay element 21 again and is circulated.
[0016]
The tone generated by this device can be read out by one of the following two methods.
(1) The n of the delay element 21 is controlled by the pitch or pitch, and the circulating data is set as a musical tone.
(2) With the n of the delay element 21 kept constant, the data read out from the delay circuit is read out while controlling the readout speed based on the pitch or pitch. This is the same as the pitch control means for cyclically reading out one cycle of a waveform in a conventional PCM reading method using a delay circuit as a waveform memory.
[0017]
Now, when the non-linear table 25 is a conversion table of a linear function as shown in FIG. 3B (in this case, it happens to be a linear conversion), the linear function is represented by [output value] = k × [input value ], The transfer function of the circuit A surrounded by the dotted line in FIG. 1 is {(Z− ¹⁻ k) / (1−k · Z− ¹ )} × Z− ¹ . On the other hand, the transfer function of the all-pass filter as shown in FIG. 5 disclosed in the first related art is (Z ⁻¹ −k) / (1−k · Z ⁻¹ ), and the two have different delay times. Just the same characteristics. Therefore, the function of the circuit of the present embodiment is equivalent to that of FIG. 5, and it can be seen that anharmonicity equivalent to that of the first prior art can be realized. Further, according to the present embodiment, it is possible to model the physical structure of a stringed instrument with a simple circuit configuration.
[0018]
In the experiment of the inventor, it has been confirmed that in the waveform obtained from the oscillation device 2 of the present embodiment, each overtone is independently modulated, and the inharmonicity of each overtone can be realized. Was.
[0019]
Next, a second embodiment of the present invention will be described with reference to FIG. This embodiment shows a modified example of creating the non-linear table, and includes a sine wave generator 31, multipliers 32 and 34, a linear function generator 33, and an adder 35 as shown. The sine wave generated from the sine wave generator 31 is multiplied by a multiplier 32 with a control signal of a time varying degree of the overtone. On the other hand, the signal generated from the linear function generator 33 is multiplied by the control signal of the degree of harmonic disharmony. The signals obtained by the two multipliers 32 and 34 are added by an adder 35 and used as a non-linear table 25.
[0020]
Using the non-linear table obtained in the second embodiment makes it possible to control the timbre according to the operation of the musical instrument player.
[0021]
【The invention's effect】
As is apparent from the above description, according to the present invention, the characteristics of the first prior art, that is, the inharmonicity, and the pseudo-modeling of the structure of the stringed instrument of the second prior art are realized. Can be realized at the same time. Therefore, according to the present invention, in a sound source system that models the physical structure of a musical instrument, it is possible to provide a sound source that generates a stringed instrument sound such as a piano, a guitar, a harpsichord, and a harp with a simpler configuration than before. Become like
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a tone signal forming device according to an embodiment of the present invention.
FIG. 2 is a block diagram showing a schematic configuration of an electronic musical instrument to which the present invention is applied.
FIG. 3 is a diagram illustrating an example of a non-linear table in FIG. 1;
FIG. 4 is a block diagram showing a configuration of a main part of the first embodiment of the present invention.
FIG. 5 is a circuit diagram showing an example of an all-pass filter.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 storage device 2 oscillating device 3 timbre control filter 4 amplitude control device 5 input device 6 central processing unit 7 audio system 21 n-stage delay elements 22 and 23 ... 1 stage delay element, 24 ... subtractor, 25 ... nonlinear table, 26 ... adder.

Claims (3)

In a musical instrument signal forming apparatus for modeling a physical structure of a musical instrument by circulating a waveform signal,
First and second delay means connected in series for delaying the waveform signal;
Means for obtaining a difference value between the waveform signal of the output of the second delay means and the waveform signal of the first delay means ;
Nonlinear conversion means for nonlinearly converting and outputting the difference value obtained by the means,
A tone signal forming apparatus comprising: an adding unit that adds data output from the non-linear conversion unit to the waveform signal between the first and second delay units. The musical tone signal forming device according to claim 1,
The tone signal forming apparatus according to claim 1, wherein the difference value represents a slope of the waveform signal . The musical tone signal forming device according to claim 1,
The tone signal forming apparatus according to claim 1, wherein said nonlinear conversion means includes nonlinear conversion data obtained by combining a trigonometric function and a linear function.

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