JP2636368B2 - Mixing equipment - Google Patents

Description

The present invention relates to a mixing device for synthesizing sounds from a plurality of sound sources such as musical instruments while adjusting the sound volume, and more particularly to a mixing device capable of automatically adjusting the sound volume of each sound source. Related to the device.

(B) Conventional technology A mixing device is used to adjust the volume of a voice or musical instrument during live music or recording. The mixing device is
A volume having a plurality of input terminals and adjusting output individually for each input is provided. By adjusting this volume, the sound of each voice or musical instrument can be output at an appropriate volume to make the sound pleasant to the audience.

By the way, the synthesized sound has a complicated frequency distribution because sounds of various voices and musical instruments are combined, and if the sound is biased, it becomes an unpleasant sound. Therefore, in order to keep the synthesized sound in an appropriate balance, it is necessary to finely adjust the volume of each instrument. That is, when the treble is too strong, the volume of the treble sound source is reduced to increase the volume of the bass sound source, and when the bass is too strong, the reverse operation is performed.

(C) Problems to be Solved by the Invention Conventionally, such operations have been performed by a professional mixer based on their own senses, experience, and knowledge. However, in order to automate this work, it is necessary to quantify the sense of pitch and loudness of the sound and to perform feedback control by combining these with a complicated algorithm, resulting in a disadvantage that the device becomes extremely complicated and expensive. Was.

An object of the present invention is to provide a mixing device that can automatically maintain the balance of synthesized sounds by using fuzzy inference in view of such a situation.

(D) Means for Solving the Problems The present invention relates to a mixing apparatus that adjusts the volume of each sound input from a plurality of sound sources and synthesizes and outputs the mixed sounds. A fuzzy inference unit for extracting a characteristic frequency of the sound source for each sound source; a fuzzy inference unit for performing fuzzy inference to maintain a balance of synthesized sounds with the characteristic frequency and the frequency distribution; And a gain control unit for adjusting the volume of the sound source based on the inference result.

(E) Function In the sound source mixing apparatus of the present invention, the sound input from the sound source is individually adjusted in volume, synthesized with the sound from another sound source, and output as a synthesized sound. The adjustment of the volume is performed as follows.

The frequency distribution of the synthesized sound is analyzed by the frequency distribution analyzer.

The characteristic frequency (peak frequency, center of gravity frequency, etc.) of each sound source is extracted by the characteristic frequency extraction unit.

Fuzzy inference is performed on the frequency distribution of the synthesized sound and the characteristic frequency. This fuzzy inference is based on a fuzzy rule that is specifically set (by the rule of thumb of an expert) on the proposition "How much volume of the sound of this sound source can be output to improve the balance of the synthesized sound?" It is done based on.

Here, the fuzzy rule is expressed in the form of if (x ₁ = A and x ₂ = B ‥‥) then (y = z), where (x ₁ = A and x ₂ = B ‥‥) is the preamble. ,
(Y = z) is called the trailing part. FIG. 4 is a diagram for explaining one known method for outputting an inference result in accordance with the fuzzy rules. FIGS. 7A and 7B show membership functions corresponding to the two terms in the leading part, and FIGS. 7C and 7C show membership functions corresponding to the trailing part.
Here, two membership functions of the front part are shown, but as the number of variables input as the conditions of the front part increases, the membership function increases accordingly. In each figure, the horizontal axis represents the value of the variable, and the vertical axis represents the membership value (degree of affiliation).

Now, the value of the variable x ₁ of the first term of the previous companion part is assumed to be x ₁ ', appertaining at that time it is 0.5. (See FIG. 3A). If the value of the variable x ₂ of the second item of the front companion part is the x ₂ ', the appertaining at that time is 0.3 (see FIG. (B)). In such a case, the fuzzy calculation unit takes the smallest value among the respective degrees of affiliation. That is, in the above example, the degree of belonging 0.3 is selected. Next, the membership function corresponding to Z is truncated at the height of 0.3. When such inference is performed for one rule, and the inference results for all rules are logically ORed, an inference value having a shape as shown by a shaded area in FIG. 4D is obtained. Normally, one quantitative value is determined, and in order to control the operation with this value, the center of gravity y ″ of the shaded portion is obtained and output as a definite value for inference.

In the above inference method, the inference product operation (operation of selecting the smaller belonging degree) rule of the degree of belonging to the frontal part and the rule of OR operation of the trapezoidal part to the back part are mini-max
They are called rules.

In the present invention, the determined value thus obtained is input to the gain control unit.

The gain control unit adjusts the volume of the sound source based on the input fixed value.

 Are performed for each sound source.

By such an operation, a plurality of sound sources can be synthesized to produce a well-balanced synthesized sound.

(F) Embodiment FIG. 1 is a diagram showing a configuration of a mixing system according to an embodiment of the present invention. The sounds of a plurality of musical instruments 1 are input to a mixer 2 having a plurality of audio input terminals, and the sounds of these musical instruments 1 are synthesized and output to a speaker amplifier 3. The sound of the musical instrument 1 is input to the mixer 2 and also to the maximum level frequency detection circuit 4. The maximum level frequency detection circuit 4 detects the peak frequency of the sound of the musical instrument 1 and outputs it to the inference unit 5. The inference unit 5 receives data of the synthesized sound together with the peak frequency. On the other hand, the mixer 2 outputs the synthesized sound to the speaker amplifier, and outputs the synthesized sound to the filters 7, 9, and 11. The filters 7, 9, and 11 are a high-pass filter, a band-pass filter, and a low-pass filter, respectively, and transmit only high-, middle-, and low-frequency sounds (high, medium, and low sounds) of the synthesized sound. The high, medium, and low sounds that have passed through the high-pass filter 7, the band-pass filter 9, and the low-pass filter 11 are input to adders 13, 14, and 15, respectively. The adders 13, 14, and 15 respectively add the treble reference value, the midtone reference value, and the bass reference value generated by the treble reference value generation circuit 8, the midtone reference value generation circuit 10, and the bass reference value generation circuit 12. (The result is subtracted because the reference value is output as a negative value.) By this addition, a value of how much the high tone, the middle tone, and the low tone of the synthesized sound are raised or lowered compared to the reference sound volume is obtained. This data is input to the inference unit 5. The inference result of the inference unit 5 is input to the gain controller 6, and the gain control 6 outputs a parameter for adjusting the volume of the mixer 2. The mixer 2 receives parameters from the gain controller 6 corresponding to each musical instrument, and adjusts the volume of each musical instrument in accordance with the parameters.

The mixer 2, the high-pass filter 7, the band-pass filter 9, the low-pass filter 11, and the high-, medium-, and low-tone reference value generation circuits 8, 10, and 12 may be incorporated. Further, the reference value (reference voltage) generated by the reference value generation circuit can be adjusted by operating a volume or the like, and the balance of the synthesized sound can be adjusted from the general sound to a certain level according to each person's preference. .

FIG. 2 shows the configuration of the inference unit 5. In FIG. 1A, the inference unit 5 includes a plurality of fuzzy operation units 20 and a defuzzification unit 21. In FIG. 2B, the fuzzy operation unit 20 has the same number of MFCs as the number of terms in the front part.
(Membership function generation circuit) 22, a conditional AND section 23, an MFC 24 corresponding to the trailing section, and a conclusion AND section 25. A variable and a membership function selection signal are input to the MFC 22 of the front part to calculate each term of the front part. This operation output is input to the conditional AND unit 23, ANDed (the minimum value is selected), and the result is input to the conclusion AND unit 25. The MFC 24 generates a membership function of the follower for inferring the control amount (gain),
To enter. Conclusion The AND unit cuts (heads off) the membership function value input from the MFC 24 with the value input from the conditional AND unit 23, and outputs it to the defuzzification unit 21 as the operation value of this fuzzy operation unit. This fuzzy calculation unit is provided with rules (if ..., ...) provided for gain control.
then ~).

In FIG. 3C, the defuzzification unit 21 is a logical sum unit.
The operation value input from the fuzzy operation unit 20 is synthesized by the OR unit 27 to determine an ambiguous (with a wide) control amount. This ambiguous control amount is input to the definite value calculation unit 28, the center of gravity of which is obtained, and this value is output to the gain controller 6 as a control amount.

FIG. 3 shows the membership function for each variable.
FIG. 3A shows a membership function for the pitch (peak frequency) of the sound source. FIG. 6B shows a membership function relating to the mixing volume (how much the volume of the high, middle, and low sounds of the synthesized sound is greater or smaller than the reference value). FIG. 3C shows a membership function of a trailing part for determining a gain (control amount).

As a rule for fuzzy inference using this membership function, for example, the following table can be considered.

In addition to the fuzzy rules shown in this table, various fuzzy rules can be considered for inferring various variables (peak frequency, high sound volume, medium sound volume, low sound volume) in various combinations.

(G) Effects of the Invention As described above, according to the present invention, a plurality of sound sources are synthesized in a well-balanced manner by setting the volume of the sound source by fuzzy inference between the frequency distribution of the synthesized sound and the characteristic frequency of the sound source. It can output comfortable sounds without specialization.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a mixing system according to an embodiment of the present invention. FIGS. 2A to 2C are block diagrams showing a configuration of an inference unit of the mixing system.
4A to 4C are diagrams showing membership functions used for inference, and FIGS. 4A to 4D are diagrams for explaining a fuzzy inference method. 1 ... musical instrument (sound source), 2 ... mixer, 5 ... inference unit,
20: Fuzzy calculation unit, 21: Defuzzification unit.

Claims (1)

(57) [Claims] A mixing device for adjusting the volume of each of the sounds input from a plurality of sound sources and synthesizing and outputting the synthesized sound, comprising: a frequency distribution analyzing unit for analyzing a frequency distribution of the synthesized sound; A characteristic frequency extraction unit for extracting a characteristic frequency of the sound source, a fuzzy inference unit for performing fuzzy inference to maintain a balance of the synthesized sound with the characteristic frequency and the frequency distribution, and a sound volume of the sound source based on the fuzzy inference result. And a gain control section that adjusts the sound pressure.