JPS6214836B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a musical tone forming method used in electronic musical instruments and the like.

[Conventional technology]

2. Description of the Related Art Various methods of forming musical tones used in electronic musical instruments and the like have been proposed in the past, one of which is known as a method of forming musical tones using frequency modulation technology. Japanese Patent Publication 1973-
The above-mentioned method is disclosed in Japanese Patent No. 126406, and according to the method described in this publication, musical tones containing a large number of harmonic components can be formed with a simple configuration.

[Problem that the invention seeks to solve]

The present invention is a further improvement on the conventional frequency modulation musical tone forming method described above, and provides a musical tone forming method that makes it possible to easily obtain a more natural-looking musical tone that has a large number of more complex harmonic components. The purpose is to

[Means for solving problems]

This invention sets the frequency relationship between the first to third frequency signals in the audible frequency range in accordance with the timbre of the musical tone to be formed, and sets the first frequency signal in accordance with the second frequency signal. The third frequency signal is frequency modulated in accordance with the signal obtained by this frequency modulation, and a musical tone is formed based on the signal obtained by this frequency modulation.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

First, in the musical tone forming method according to the present invention, a musical sound waveform is formed based on, for example, the following basic formula for frequency modulation calculation.

In the embodiment described below, a tone waveform is formed by the following equation in which i=1, j=1, and k=1 in the above basic equation (1).

y=A SIN {ω ₀ t + I ₂ SIN (ω ₂ t + I ₁ SINω ₁ t)} ... (1a) In this equation (1a), A is the element that determines the amplitude of the musical sound waveform, and ω ₀ is the frequency It is the element that determines the frequency of the carrier wave in modulation, and also ω
₁ , ω ₂ and I ₁ , I ₂ are elements that determine the frequency and amplitude of a modulated wave in frequency modulation.

In general, ω ₀ , ω ₁ , ω ₂ are set corresponding to the pitch frequency of the musical tone to be formed, and ω
The ratio of ₀ , ω ₁ and ω ₂ is set corresponding to the tone to be formed. The basic configuration of high frequencies (harmonics) included in a musical tone is determined according to the ratio of ω ₀ , ω ₁ , and ω ₂ , and the level of each harmonic is controlled according to the values of I ₁ and I ₂ .

FIG. 1 is a diagram showing an example of the basic circuit configuration when forming a musical sound waveform by digital technology based on equation (1a) above.
ACC1 to ACC3 are all accumulators. These accumulators ACC1 to ACC3 each receive phase increment values △ω ₁ , △ω ₂ , △ω ₀ supplied to each input terminal.
are accumulated according to a clock pulse of a constant period, and the accumulated results are sequentially output as phase data ω ₁ t, ω ₂ t, ω ₀ t. The sine table SIN1 is a memory that stores each instantaneous value of the sine waveform, and when the output ω ₁ t of the accumulator ACC1 is supplied as an address signal, it is stored in the address corresponding to the same address signal. Instantaneous values are read out.

In this case, each instantaneous value of the sine wave for exactly one cycle is sequentially read from the sine table SIN1 during the period from when the accumulator ACC1 starts accumulating from "0" until it overflows. Here, the accumulation speed of the accumulator ACC1 is constant because the period of the clock pulse is constant. Therefore, if the phase increment value △ _ω1 is constant, the sine output from the sine table SIN1 is constant. The period of the wave is constant. In other words, by changing the value of the phase increment value △ω ₁ , the sine table SIN
The period (frequency) of the sine wave output from 1 can be changed. For example, the phase increment value △
If ω ₁ is made large, the period of the sine wave becomes small,
Furthermore, if the increment value Δω ₁ is made small, the period of the sine wave becomes large.

Next, SIN2 and SIN3 in FIG. 1 are sign tables configured similarly to the above-described sign table SIN1, and M1 to M3 are multipliers that multiply input data by values I ₁ , I ₂ , and A, respectively. , ADD1,
ADD2 is an adder. The outputs of these components have the values shown in the figure, and the musical tone signal expressed by equation (1a) is obtained as the output of the multiplier M3.

The basic configuration of the musical sound wave forming circuit has been described above. Next, an electronic musical instrument to which the musical sound forming method according to this embodiment is applied will be explained. FIG. 2 is a block diagram showing the configuration of the electronic musical instrument. In this figure, 101 is a tone lever for setting the tone of a musical tone, 102 is a group of keys provided on the keyboard,
103 is a key assigner, 105 is for data storage
RAM 106 is a ROM in which programs and tone parameters used in the key assigner 103 are stored. Here, the musical tone parameters are △ω ₁ , △ω ₂ , △
ω ₀ , I ₁ , I ₂ and parameters for forming an envelope waveform signal. As is well known, this envelope waveform signal controls the amplitude envelope of the musical tone to be formed, and changes in response to key on/off, as shown in FIG. 3, for example. This envelope waveform signal is used as A explained in FIG. Note that the parameters for forming the envelope waveform signal include, for example, the envelope increment value that determines the slope of the rising and falling parts of the envelope waveform signal (a positive value for the rising part,
In the falling part, it is a negative value) ΔA. ROM10
6, these tone parameters are stored corresponding to each tone set by the tone lever 101 and corresponding to each key of the key group 102. For example, △ω ₁ , △ω ₂ ,
△ω ₀ is stored for each tone and for each key,
I ₁ , I ₂ , and ΔA are stored for each tone. The key assigner 103 scans the tone lever 101 and the key group 102 to detect the operating state of each lever and key. When a newly turned on key is detected, the musical tone parameter corresponding to the key and the tone currently selected and set by the tone lever 101 is stored in the ROM 106.
, and outputs it to the wave generator 104 together with a key-on signal (start signal).
Furthermore, when a key-off is detected, a key-off signal (decay signal) is sent to the wave generator 104.
Output to.

The wave generator 104 is composed of a data port 107 and a musical waveform forming section 108. Data port 107 is key assigner 1
03, and the stored parameters are stored in the musical sound waveform forming section 108.
Output to. The musical sound waveform forming section 108 performs the calculation shown in FIG. 1 based on the musical tone parameters to form a musical tone signal. In this case, in addition to each circuit element shown in FIG. 1, the musical sound waveform forming section 108 is provided with an envelope waveform generator that forms an envelope waveform signal and outputs it to the multiplier M3 in FIG.
This envelope waveform generator generates and outputs an envelope waveform signal as shown in FIG. 3 by accumulating the above-mentioned envelope increment value ΔA upon receiving the key-on signal and the key-off signal. The musical sound signal formed by the musical sound waveform forming section 108 is supplied to a sound system (not shown) comprising an amplifier, a speaker, etc. via a DA converter (not shown), and is produced as a musical sound.

In this way, a musical tone having a pitch corresponding to the key pressed on the keyboard and corresponding to the tone color selected by the tone color lever is formed according to equation (1a).

In addition, in the above embodiment, musical tone parameters
I ₁ and I ₂ may be changed over time according to an arbitrary envelope waveform. Further, a plurality of musical sound generation channels are provided in the musical sound waveform forming section 108, and each key turned on in the key assigner 103 is assigned to a currently vacant musical sound generation channel. The musical tone signal corresponding to the key may be formed based on the equation (1a). In this case, the circuit shown in FIG. 1 may be used in time division for each channel.

〔Effect of the invention〕

As explained above, according to the present invention, the frequency relationship between the first to third frequency signals in the audible frequency range is set corresponding to the timbre of the musical tone to be formed, and the first frequency signal is Frequency modulation is performed according to the second frequency signal, frequency modulation is performed on the third frequency signal according to the signal obtained by this frequency modulation, and musical tone is generated based on the signal obtained by this frequency modulation. As a result, a natural-looking musical tone having a large number of complex harmonic components can be formed with a simple configuration. Further, according to the present invention, by appropriately setting the frequencies of the first to third frequency signals, it is possible to form a musical tone having a peak of the spectral envelope at a desired overtone without changing the hardware. be.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a musical tone forming circuit to which a musical tone forming method according to an embodiment of the present invention is applied, FIG. 2 is a block diagram showing the configuration of an electronic musical instrument to which the same musical tone forming circuit is applied, and FIG. 3 is an envelope waveform diagram of a musical tone. ACC1 to ACC3...accumulator, SIN1 to SIN3...sine table, M1 to M3...multiplier, ADD1,
ADD2...Adder.

Claims (1)

[Claims] 1. The frequency relationship between the first to third frequency signals in the audible frequency range is set in accordance with the timbre of the musical tone to be formed, and the first frequency signal is frequency modulated according to the second frequency signal. . A musical tone forming method, characterized in that the third frequency signal is frequency modulated in accordance with the signal obtained by this frequency modulation, and a musical tone is formed based on the signal obtained by this frequency modulation.