JPH0772835B2 - Music synthesizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a so-called delay, which is a musical tone synthesizing device for inputting an initial waveform signal to a closed loop including a delay means and circulating it in the closed loop to synthesize a musical tone. The present invention relates to a tone synthesizer using a feedback tone synthesis algorithm.

[Prior Art] Conventionally, as a so-called digital sound source used in electronic musical instruments and the like, initial waveform data is stored in a closed loop including a delay circuit,
Tones are synthesized by inputting data such as impulse signal data and nonlinear signal data and performing regression calculation processing.
A tone synthesizer using a so-called delayed feedback type attenuated tone synthesis algorithm is known (Japanese Patent Publication No. 58-5867).
9, JP-B-58-48109, JP-B-59-7396, JP-A-62
-143097, JP-A-63-80300, JP-A-63-40199, etc.).

These tone synthesizers are used for wind instruments such as wind instruments and strings of stringed instruments.
The mechanical vibration system of a natural musical instrument is physically approximated by an electric circuit, and the delay time of the delay circuit corresponds to the resonance frequency of the mechanical vibration system, that is, the pitch (pitch) of the musical sound to be generated.

By the way, in such a musical sound synthesizer, generally, a waveform memory storing sequential sample point data for one wavelength of a desired initial waveform is used as an initial waveform data input means, and a shift register, a BBD are used as a delay circuit. And RAM is used. The pitch is set by changing the cycle of the clock for driving the delay circuit. At this time, the clock for reading the waveform memory is also moved and set variably.

FIGS. 6 (a) and 6 (b) show the spectrum distribution of musical tones synthesized by such a conventional musical tone synthesizer. The same figure (a)
From (b) and (b), this tone is a formant tone, and the pitch and the spectrum envelope are interlocked so that the width of the spectrum envelope becomes wider (narrower) as the pitch becomes higher (or lower). I understand. In the following, the formant in which the pitch and the spectrum envelope are linked in this way is referred to as a moving formant.

The moving formant, in which the balance of the line spectrum is constant between the fundamental and the overtone, is also useful as such. However, as a musical sound, a formant sound in which the absolute frequencies of the peaks and valleys of the spectrum envelope are constant regardless of the pitch (hereinafter referred to as fixed formant sound)
Also, a formant sound (hereinafter referred to as a semi-fixed formant sound) that moves to some extent in accordance with the pitch but whose frequency spectrum does not necessarily change in proportion to the pitch is also important.

[Problem to be Solved by the Invention] An object of the present invention is to provide a musical tone synthesizing device using a delay feedback type musical tone synthesizing algorithm, which is capable of generating a fixed or semi-fixed formant tone. .

[Means for Solving the Problem] In order to achieve this object, in the present invention, the delay time setting of the delay means and the period of the initial waveform signal in the delay feedback type tone synthesis algorithm are set independently. .

[Operation and Effect] The formant tone synthesized by such a tone synthesizer has a pitch (fundamental tone) corresponding to the delay time of the delay means and an envelope corresponding to the initial waveform signal.

According to this invention, the delay time of the delay means and the period of the initial waveform signal can be set independently. Therefore,
By changing the delay time of the delay means while keeping the period of the initial waveform signal constant, only the pitch can be variably set without changing the envelope (fixed formant),
Further, by changing the period of the initial waveform signal according to the range or a desired ratio of the amount of change in the delay time, it is possible to synthesize a formant sound (semi-fixed formant) in which the change in the envelope is smaller than the change in the pitch. . Further, if the change width of the period of the initial waveform signal is made larger than the change width of the delay time, it is possible to synthesize a formant sound having a larger envelope change than a pitch change.

[Examples] Hereinafter, the present invention will be described in detail based on examples.

FIG. 1 is a block diagram showing the basic structure of a musical tone synthesizing apparatus using a delayed feedback type musical tone synthesizing algorithm according to an embodiment of the present invention.

The apparatus shown in the figure comprises a phase accumulator 1, a delay feedback type tone synthesis algorithm 2, a counter 3, a waveform memory 4 and a control circuit 5.

The control circuit 5 sends the reset signal RS to the counter 3 in response to the key-on timing of the musical tone to be generated, and inputs the F number (delay time information value) ΔF corresponding to the pitch of the musical tone to the phase accumulator 1. .

The counter 3 is reset by a reset signal supplied from the control circuit 5 and counts a fixed frequency system clock φ sent from a clock generator (not shown). The count value output of the counter 3 is given to the waveform memory 4 as an address signal.

The waveform memory 4 stores each sample point data of the initial waveform of the musical sound to be generated, and the sample point data stored at the address is sequentially read according to the address signal. The read data is input to the delay feedback type musical tone synthesis algorithm 2.
In this case, the counter 3 that addresses the waveform memory 4 is controlled by the system clock φ having a fixed cycle φ,
The initial waveform is always read from the waveform memory 4 at a constant sampling frequency.

The phase accumulator 1 accumulates the F number ΔF from “0” every time the system clock φ is input.
Accumulation is performed in the range of "1", and when the accumulated value reaches the value "1" corresponding to 2π, a carry output C _O is generated. As a result, if the F number ΔF is set to 0.5, for example, the cycle of the control clock, that is, the carry output C _O becomes 2φ.
Further, when the F number ΔF is set to 0.66 ..., The control clock C _O has the first, third, fifth, and sixth periods by thinning out the second and fourth periods of every six periods of the system clock φ. Occur. Therefore, in this case, the average period of the control clock is 6 / 4φ.

The delay feedback type tone synthesis algorithm 2 includes a delay circuit (not shown), a circulation circuit which circulates the output of this delay circuit to the input side, and the output of this circulation circuit and the output of the waveform memory 4 are added to the delay circuit. It is composed of an adder for inputting. In this synthesizing algorithm 2, the delay circuit operates using the carry output C _O sent from the phase accumulator 1 as a control clock, and the data input via the adder is timed according to the control clock C _O. Only output after delaying. In this way, since the synthesis algorithm 2 controls the delay time by the carry output C _O of the cycle corresponding to the F number ΔF sent from the phase accumulator 1, the pitch (fundamental tone) can be freely set. it can.

2 (a) to 2 (C) each show an example of a configuration applicable as the delay feedback type musical tone synthesis algorithm 2 in FIG. Fig. 2 (a) is the applicant's Japanese Patent Publication
It is a damped sound algorithm described in 58-58679.
This synthesizing algorithm can also be used for synthesizing connection sounds by continuing to input. Fig. 2 (b)
FIG. 2 (c) shows a VLPF type continuous sound algorithm described in Japanese Patent Application Laid-Open No. 61-107298 by the present applicant. This is a combined continuous sound synthesis algorithm.

FIG. 5 shows the configuration of a conventional tone synthesizer using a delay feedback type tone synthesis algorithm. In this type of algorithm, the pitch F _P of the musical tone to be synthesized is given by F _P = F _C / τ. Here, F _C is the frequency of the control clock of the algorithm, and τ is the delay time in the algorithm.

In order to variably control the pitch F _P , it is necessary to change the clock frequency F _C or the delay time τ. In this case, if a shift register or BBD is used as the delay circuit and F _C is fixed, the delay time τ will be variable by varying the number of stages of the shift register or BBD, and will be an integer value according to the number of stages. It can only be changed. Therefore, it is difficult to realize each pitch of the scale constituent tones. Furthermore, it is impossible to control the delay time τ with high precision in response to vibrato, pitch bend, and the like. Therefore, the clock frequency F _C is freely changed in proportion to the desired pitch frequency. The counter 3 is for generating an address for reading the initial waveform from the waveform memory 4.
Since this counter 3 operates at the same clock as the synthesis algorithm 2, the initial waveform given to the synthesis algorithm 2 and the synthesis algorithm 2 operate in perfect synchronization.

Also in the conventional apparatus shown in FIG. 5, the combination algorithm 2 shown in FIG. 2 can be used. This type of synthesis algorithm constitutes a comb filter having a peak at a frequency that is approximately an integral multiple of the pitch frequency. Therefore, when this synthesis algorithm is applied to the configuration shown in FIG. 5, the spectrum included in the input waveform is also shifted upward by raising the clock frequency in order to raise the pitch. As a result, in the device of FIG. 5, the spectral structure seen from the balance between overtones is constant regardless of the pitch frequency, but the absolute frequencies of the peaks and valleys of the spectral envelope shift according to the pitch frequency. It becomes a moving formant.

In the apparatus of FIG. 1, the counter 3 for addressing the waveform memory 4 is controlled from the fixed system clock φ, so that the waveform memory 4 reads the waveform at the same sample frequency F _C regardless of the pitch frequency. . On the other hand, since the synthesis algorithm 2 side is controlled via the phase accumulator 1, the basic pitch can be set freely. In this case, the frequency F _d of the carrier output (control clock) C _O of the phase accumulator 1 is F _d = ΔF × F _C , and the basic pitch F _P is F _P = F _d / τ = ΔF × F _C / τ Given in. As a result, as shown in FIGS. 3 (a) and 3 (b), the pass line spectrum of the synthesis algorithm 2 becomes coarser as the pitch increases, but the spectral structure of the envelope waveform is fixed with respect to the absolute frequency, and the synthesis is performed. The played musical sound has a fixed formant structure.

FIG. 4 shows the configuration of a musical sound synthesizer according to another embodiment of the present invention. This device has a second phase accumulator 6 added to that of FIG. 1, and the control circuit 5 controls the phase accumulators 1 and 6 independently of the F number ΔF ₁
Together give and [Delta] F _2, it is obtained by adapted to the counter 3 at the key-on timing provide a reset signal RS. In this way, by separately providing the phase accumulator for the waveform memory reading and the synthesis algorithm, it is possible to freely control the formant. That is, since the reading speed of the waveform can be controlled independently of the pitch on the algorithm side, the spectrum of the output tone waveform is in the middle half between the moving formant shown in FIG. 6 and the fixed formant shown in FIG. It is also possible to set a fixed formant state.

In such a configuration, since the sampling rate of waveform reading is different from the sampling rate of the algorithm, interpolation is originally required when data is transferred. However, even if this interpolation is omitted, it is equivalent to the interpolation of the zero-order hold type, and although some wrapping occurs, it occurs only when the data is delivered to and from the algorithm side, and the spectrum of the initial waveform is only distorted to some extent. So it is not a big problem. Therefore, even if interpolation is introduced, a simple one such as linear interpolation is sufficient. When the interpolation circuit is provided, it is inserted between the waveform memory 4 and the delay feedback type tone synthesis algorithm 2 shown in FIG.

In the above description, the embodiment in the digital system is shown, but the present invention can also be applied to the analog system. In this case, it is preferable that the phase accumulator 1 and the counter 3 are digital processing systems and only the arithmetic circuits are analog processing systems.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a musical sound synthesizing apparatus according to an embodiment of the present invention, and FIGS. 2 (a) to 2 (c) are concrete configuration examples of the delay feedback algorithm in FIG. FIG. 3 is a block diagram showing the spectrum distribution of a musical tone synthesized by the apparatus shown in FIG. 1, and FIG. 4 is a block diagram showing the basic configuration of a musical tone synthesizing apparatus according to another embodiment of the present invention. FIG. 5 is a block diagram showing the basic configuration of a conventional musical tone synthesizing apparatus, and FIG. 6 is a spectrum distribution explanatory diagram of musical tones synthesized by the apparatus of FIG. 1,6: Phase accumulator, 2: Delayed feedback tone synthesis algorithm 3: Counter, 4: Waveform memory, 5: Control circuit.

Claims (1)

[Claims] 1. A musical tone synthesizer for inputting an initial waveform signal to a closed loop including delay means to perform a circulation process in the closed loop to synthesize a musical sound, wherein a delay time of the delay means and a period of the initial waveform signal are combined. A musical tone synthesizer characterized by being set independently.