Sound quality improvement device and sound quality improvement method for removing dissonance of rotary machine

Abstract

To provide technology capable of improving listening comfort of operation sound by reducing a dissonance degree of operation sound.SOLUTION: A sound quality improvement device 6 calculates a difference D between a first peak frequency f1 and a second peak frequency f2, which are contained in on-site sound including operation sound of a rotary machine 1, determines critical bandwidth C of the first peak frequency f1, the second peak frequency f2, an average frequency of the first peak frequency f1 and the second peak frequency f2, or a frequency between the first peak frequency f1 and the second peak frequency f2 and reduces a sound component by generating opposite phase sound having a phase opposite to a sound component of the first peak frequency f1 or the second peak frequency f2 when the difference D is smaller than the critical bandwidth C.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a technique for improving the comfort of hearing the operating sounds of rotating machines, such as pumps, blowers, compressors, turbines, and electric motors, by reducing the degree of inharmonicity of the operating sounds generated by the rotating machines. [Background technology]

[0002] Rotating machines such as pumps, blowers, compressors, turbines, and electric motors are devices in which a rotor (e.g., an impeller, a roots rotor, or a motor rotor) rotates at high speed. Therefore, the rotating machines generate operating noise during operation. The operating noise of rotating machines can sometimes be unpleasant to people. Thus, in order to improve the audibility of the operating noise, efforts have been made to reduce noise using the noise level as an evaluation criterion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 6-303103 [Patent Document 2] JP 2005-278158 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, reducing the noise level may not improve the listening experience. This is because the operating sound contains harsh frequency components, or components with close frequencies may cause humming or increase in inharmonicity. The multiple components of the rotational frequency of a rotating machine are far apart in frequency, so the inharmonicity of these harmonic components is seldom high. However, when the frequency of the sound generated by components such as the motor and bearings included in the rotating machine is close to the rotational frequency of the rotating machine, or when there is another rotating machine adjacent that has different specifications such as rotation speed or number of blades on the impeller, interference between multiple sounds may occur or the inharmonicity of the sounds may increase. Furthermore, the inharmonicity may increase due to the influence of noise transmitted from outside.

[0005] Therefore, the present invention provides a technique that can improve the listening comfort of operation sounds by reducing the degree of inharmonicity of the operation sounds. [Means for solving the problem]

[0006] In one aspect, a sound quality improvement device for removing dissonance from a rotating machine is provided, the sound quality improvement device comprising: a microphone for collecting on-site sounds including operation sounds of the rotating machine; and an anti-phase sound generator for reducing the dissonance of the on-site sounds by reducing any of a plurality of sound components contained in the on-site sounds. The anti-phase sound generator is configured to acquire the on-site sounds from the microphone, perform frequency analysis on the on-site sounds, calculate a difference between a first peak frequency and a second peak frequency contained in the on-site sounds, determine a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency, and, when the difference is smaller than the critical bandwidth, generate an anti-phase sound having an opposite phase to the sound component of the first peak frequency or the second peak frequency, thereby reducing the sound component.

[0007] In one aspect, the antiphase tone generator is configured to generate the antiphase tone when a ratio of the difference to the critical bandwidth is within a range of 0.01 to 0.55. In one aspect, the antiphase sound generator is configured to select the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, so that a plurality of sound components in the on-site sound remaining after the sound components are reduced become consonant. In one embodiment, the antiphase sound generator has a storage device that stores a combination of a plurality of frequencies that constitute a consonant sound, and the antiphase sound generator is configured to select the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, so that the plurality of sound components remaining after reducing the sound components have the combination of the plurality of frequencies that constitute the consonant sound. In one aspect, the combination of the plurality of frequencies is determined based on a model of the rotating machine. In one aspect, the anti-phase sound generator is configured to repeatedly acquire the on-site sound from the microphone, perform a frequency analysis on the on-site sound, calculate a difference between a first peak frequency and a second peak frequency contained in the on-site sound, determine a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency, and generate an anti-phase sound having an inverse phase to the sound component of the first peak frequency or the second peak frequency when the difference is smaller than the critical bandwidth.

[0008] In one aspect, a sound quality improvement method for removing dissonance from a rotating machine is provided, the sound quality improvement method including: collecting on-site sounds including an operation sound of the rotating machine with a microphone; and performing an anti-phase sound generating operation for reducing a degree of dissonance of the on-site sounds by reducing any one of a plurality of sound components contained in the on-site sounds; the anti-phase sound generating operation includes acquiring the on-site sounds from the microphone; performing a frequency analysis on the on-site sounds; calculating a difference between a first peak frequency and a second peak frequency contained in the on-site sounds; determining a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency; and, when the difference is smaller than the critical bandwidth, generating an anti-phase sound having an inverse phase to the sound component of the first peak frequency or the second peak frequency, thereby reducing the sound component.

[0009] In one embodiment, the antiphase tone is generated when the ratio of the difference to the critical bandwidth is within a range of 0.01 to 0.55. In one embodiment, the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, is selected so that multiple sound components in the on-site sound remaining after the sound component is reduced are consonant. In one embodiment, the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, is selected so that the plurality of sound components remaining after the reduction of the sound component has a combination of a plurality of pre-set frequencies that constitute a consonant sound. In one aspect, the combination of the plurality of preset frequencies is determined based on a model of the rotating machine. In one aspect, the sound quality improving method further comprises repeating the anti-phase sound generating operation. Effect of the Invention

[0010] When the difference between the first peak frequency and the second peak frequency is smaller than the critical bandwidth, the sound components of the first peak frequency and the second peak frequency interfere with each other to generate a dissonant sound. Therefore, when the difference is smaller than the critical bandwidth, the sound components of the first peak frequency or the second peak frequency are reduced to reduce the dissonant degree of the site sound, and the listening comfort of the site sound including the operating sound of the rotating machine can be improved. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram illustrating an embodiment of a mechanical system including a rotating machine and a sound quality improvement device. [Diagram 2] FIG. 13 is a schematic diagram showing another embodiment of a sound quality improving device. [Diagram 3] 1 is a graph showing an example of a frequency analysis result of an operating sound of a turbo pump, which is an example of a rotating machine. [Figure 4] 11 is a graph showing a frequency spectrum for explaining an antiphase sound generating operation. [Diagram 5] 1 is a graph showing a dissonance curve. [Figure 6] 1 is a graph showing an example of the results of a frequency analysis performed on field sounds including the operating sounds of a rotating machine. [Figure 7] 11 is a graph showing another example of the results of a frequency analysis performed on field sounds including the operating sounds of a rotating machine. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a sound quality improving device and a sound quality improving method for removing discordant sounds from rotating machinery will be described with reference to the drawings. Fig. 1 is a schematic diagram showing one embodiment of a mechanical system including a rotating machine and a sound quality improving device. As shown in Fig. 1, the mechanical system has a rotating machine 1 and a sound quality improving device 6. The sound quality improving device 6 is installed adjacent to the rotating machine 1, or at a distance from the rotating machine 1, or in contact with the rotating machine 1.

[0013] The rotating machine 1 includes a rotor 3 which is a rotating body, a bearing 5 which rotatably supports the rotor 3, and a base 10 on which the bearing 5 is mounted. The base 10 has a bearing holder 12 which holds the bearing 5. The rotor 3 is connected to a drive source (not shown) such as an electric motor, and is rotated by the drive source. Examples of the rotating machine 1 include a pump, a blower, a compressor, a turbine, and an electric motor. Specific examples of the rotor 3 include an impeller, a Roots rotor of a Roots-type pump, and a motor rotor of an electric motor.

[0014] The sound quality improving device 6 is configured to analyze on-site sounds including the operation sound of the rotating machine 1, and reduce any one of a plurality of sound components included in the on-site sounds, thereby reducing the degree of dissonance of the on-site sounds. The sound quality improving device 6 has a microphone 14 that collects on-site sounds including the operation sound of the rotating machine 1. The microphone 14 is disposed in a position where it can collect at least the operation sound of the rotating machine 1. The microphone 14 collects not only the operation sound of the rotating machine 1, but also sounds other than the rotating machine 1 (e.g. external sounds such as environmental sounds). For example, the microphone 14 collects the operation sounds of other rotating machines adjacent to the rotating machine 1.

[0015] The sound quality improving device 6 includes an anti-phase sound generator 7 configured to reduce any one of a plurality of sound components contained in the on-site sound collected by the microphone 14. The sound quality improving device 6 of this embodiment is an active noise canceling system that reduces an original sound by generating an anti-phase sound having a phase opposite to that of the original sound. The anti-phase sound generator 7 executes an anti-phase sound generating operation to generate an anti-phase sound having a phase opposite to that of the sound component to be reduced. The anti-phase sound generator 7 is electrically connected to the microphone 14 that collects on-site sounds including the operation sound of the rotating machine 1.

[0016] The antiphase sound generator 7 includes a sound source 8 that generates an antiphase sound that reduces the inharmonicity of the on-site sound, and an operation control unit 20 that controls the operation of the sound source 8. In the embodiment shown in FIG. 1, the sound source 8 is an electric sound source that electrically generates an antiphase sound. In one example, the sound source 8 includes a sound wave generator 15 that generates a sound signal of a variable frequency, an amplifier 16 that amplifies the sound signal, and a speaker 17 that emits the amplified sound signal as an antiphase sound. However, as long as the antiphase sound can be generated, the specific configuration of the sound source 8 is not limited to the embodiment shown in FIG. 1. The sound quality improvement device 6 further includes an input device 21 for inputting data and command values. The input device 21 is electrically connected to the operation control unit 20. Specific examples of the input device 21 include a keyboard, a mouse, and a numeric keypad.

[0017] The microphone 14 is an electric device that converts sound into an electric signal. The sound quality improving device 6 of this embodiment is a feedback type noise canceling system. That is, the microphone 14 has a function of collecting on-site sounds including the operation sound of the rotating machine 1, and further functions as an error microphone that collects a composite sound of the on-site sounds and the antiphase sound emitted from the speaker 17 of the sound source 8.

[0018] The microphone 14 is electrically connected to the operation control unit 20, and the on-site sound converted into an electric signal by the microphone 14 is sent to the operation control unit 20. The microphone 14 is placed at a position where it can collect a composite sound of the on-site sound of the rotating machine 1 and the anti-phase sound emitted from the speaker 17. More specifically, the microphone 14 is set at a sound receiving point where the user can hear the on-site sound of the rotating machine 1. Alternatively, the microphone 14 is set close to a position where the rotating machine 1 radiates sound.

[0019] The operation control unit 20 includes a storage device 20a in which a program is stored, and a calculation device 20b that executes calculations according to instructions included in the program. The operation control unit 20 is composed of at least one computer. The storage device 20a includes a main storage device such as a random access memory (RAM), and an auxiliary storage device such as a hard disk drive (HDD) or a solid state drive (SSD). Examples of the calculation device 20b include a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). However, the specific configuration of the operation control unit 20 is not limited to these examples.

[0020] In one embodiment, the sound quality improving device 6 may be a feedforward type noise canceling system. As shown in Fig. 2, the sound quality improving device 6 as a feedforward type noise canceling system further includes a reference microphone 25 for collecting on-site sounds. The reference microphone 25 is disposed adjacent to the rotating machine 1. For example, as shown in Fig. 2, the reference microphone 25 is disposed adjacent to the rotor 3. Alternatively, the reference microphone 25 is disposed on a path of the operation sound of the rotating machine 1 from the rotating machine 1 to a user.

[0021] As long as the sound quality improving device 6 can reduce the degree of dissonance of the on-site sound by reducing any one of a plurality of sound components contained in the on-site sound, the sound quality improving device 6 may be installed at a location away from the rotating machine 1. For example, the sound quality improving device 6 may be set at a sound receiving point where the user can hear the on-site sound of the rotating machine 1, or may be set at a sound receiving point where the user cannot hear the operation sound of the rotating machine 1. In yet another example, the sound quality improving device 6 may be a portable device that the user can carry with him / her.

[0022] The operating sound of the rotating machine 1 is basically generated due to the rotation of the rotor 3. Therefore, the operating sound of the rotating machine 1 has a frequency that depends on the rotation speed (rotation frequency) of the rotor 3. The rotation speed of the rotor 3 may be constant or may be variable. The dominant frequency of the operating sound of the rotating machine 1 is basically N times the rotation frequency fn of the rotor 3 (Nfn). The symbol N is a natural number. The rotor 3 has protrusions that are functional protrusions such as the blades of an impeller and the lobes of a roots rotor.

[0023] If the number of blades on the impeller of a pump, which is an example of a rotating machine 1, is z, the range of N, which corresponds to the main frequencies contained in the operating sound, is approximately 1≦N≦3z to 5z for turbo pumps such as feedwater pumps and drainage pumps. In a Roots-type pump, if the number of blades on the Roots rotor is z, then it is approximately 1≦N≦10×2z.

[0024] Fig. 3 is a graph showing an example of the frequency analysis results of the operating sound of a turbo pump, which is an example of a rotating machine 1. In Fig. 3, the horizontal axis represents the frequency of the operating sound, and the vertical axis represents the intensity of the frequency components contained in the operating sound. When an impeller, which is an example of a rotor 3, has five blades (z=5), the range of N as the operating sound is 25 or less (N≦25). The symbol fn represents the rotational frequency of the rotor 3. As shown in Fig. 3, in the high frequency band, the intensity of the frequency components decreases as the frequency increases.

[0025] Sound components with frequencies N times the rotation frequency contained in the operating sound of the rotating machine 1 harmonize with each other to form a consonant sound. However, if the frequency of the sound generated from components such as the bearings 5 ​​included in the rotating machine 1 is not N times the rotation frequency of the rotating machine 1, or if there is another rotating machine adjacent that has different specifications such as a different rotation speed or the number of blades on the impeller, interference between the multiple sounds may occur or the discordance between the sounds may become greater.

[0026] Therefore, the sound quality improving device 6 collects on-site sounds including the operating sounds of the rotating machine 1 and ambient sounds with the microphone 14, analyzes the on-site sounds, and generates an antiphase sound corresponding to any of a plurality of sound components contained in the on-site sounds, thereby performing an antiphase sound generating operation to reduce the sound components. The antiphase sound generating operation of the sound quality improving device 6 will be described in detail below.

[0027] The anti-phase sound generator 7 is configured to acquire a site sound from the microphone 14, perform a frequency analysis on the site sound, calculate a difference between a first peak frequency and a second peak frequency contained in the site sound, determine a critical bandwidth of the first peak frequency, and reduce the sound component by generating an anti-phase sound having an anti-phase to the sound component of the first peak frequency or the second peak frequency when the difference is smaller than the critical bandwidth. The first peak frequency and the second peak frequency are the frequencies of any two peaks among the multiple peaks of the frequency components contained in the site sound.

[0028] Fig. 4 is a graph showing a frequency spectrum for explaining the antiphase sound generating operation. In Fig. 4, the horizontal axis represents the frequency of the on-site sound, and the vertical axis represents the intensity of the frequency components contained in the on-site sound. The frequency spectrum is obtained by performing frequency analysis on the on-site sound. Examples of frequency analysis include Fourier transform and fast Fourier transform.

[0029] In the example shown in FIG. 4, the frequency of the on-site sound includes a first peak frequency f1 and a second peak frequency f2. That is, the on-site sound includes a sound component of the first peak frequency f1 and a sound component of the second peak frequency f2. The operation control unit 20 of the antiphase sound generator 7 calculates the difference D between the first peak frequency f1 and the second peak frequency f2, determines the critical bandwidth C of the first peak frequency f1, and when the difference D is smaller than the critical bandwidth C, issues a command to the sound source 8 to cause the sound source 8 to generate an antiphase sound having a phase opposite to that of the sound component of the first peak frequency f1 or the second peak frequency f2. The critical bandwidth refers to a band (width) at which the noise level in the frequency band starts to increase when the frequency band (width) is increased under a constant sound pressure level condition. The critical bandwidth may vary depending on its center frequency.

[0030] More precisely, the first peak frequency f1 or the second peak frequency f2 is converted to the Bark scale (Bark) using the following conversion formula from frequency (Hz) to the Bark scale (Bark), and this is called Bark 1 or Bark 2. For example, the critical bandwidth C of the first peak frequency f1 is in the range of Bark 1 ±0.5.

number

[0031] In the embodiment shown in FIG. 4, the operation control unit 20 is configured to determine the critical bandwidth C of the first peak frequency f1 and determine whether the difference D is smaller than the critical bandwidth C. In one embodiment, the operation control unit 20 may be configured to determine the critical bandwidth of the second peak frequency f2 and determine whether the difference D is smaller than the critical bandwidth of the second peak frequency f2. In another embodiment, the operation control unit 20 may be configured to calculate the average frequency of the first peak frequency f1 and the second peak frequency f2, determine the critical bandwidth of the average frequency, and determine whether the difference D is smaller than the critical bandwidth. In yet another embodiment, the operation control unit 20 may be configured to select a frequency between the first peak frequency f1 and the second peak frequency f2, determine the critical bandwidth of the selected frequency, and determine whether the difference D is smaller than the critical bandwidth. The operation control unit 20 stores correlation data indicating the relationship between the frequency and the critical bandwidth in the storage device 20a in advance.

[0032] When the difference D between the first peak frequency f1 and the second peak frequency f2 is smaller than the critical bandwidth, the sound components of the first peak frequency f1 and the second peak frequency f2 interfere with each other to generate a dissonant sound. This is based on the dissonance curve described below.

[0033] FIG. 5 is a graph showing a dissonance curve. In FIG. 5, the vertical axis represents the degree of dissonance, and the horizontal axis represents the ratio of the frequency difference to the critical bandwidth. The ratio of the frequency difference to the critical bandwidth is a numerical value obtained by dividing the difference between two frequencies by the critical bandwidth of the lower frequency (the frequency of the root tone). Dissonance is an index that indicates the degree to which a person feels uncomfortable, and is determined experimentally or statistically. Specifically, the dissonance of a sound that all subjects find unpleasant is 1, and the dissonance of a sound that all subjects do not find unpleasant is 0.

[0034] As shown in Figure 5, when the ratio of the frequency difference to the critical bandwidth (frequency difference / critical bandwidth) is less than 1.0, i.e., when the difference between two frequencies is smaller than the critical bandwidth, the degree of dissonance is greater than 0. In other words, when the difference between two frequencies is smaller than the critical bandwidth, the two sound components having those frequencies constitute a dissonant sound.

[0035] Therefore, the operation control unit 20 calculates the difference D between the first peak frequency f1 and the second peak frequency f2 of the on-site sound, determines the critical bandwidth C of the first peak frequency f1, and when the difference D is smaller than the critical bandwidth C, issues a command to the sound source 8 to cause the sound source 8 to generate an anti-phase sound having an anti-phase to the sound component of the first peak frequency f1 or the second peak frequency f2. The anti-phase sound can cancel out the sound component of the first peak frequency f1 or the second peak frequency f2. As a result, the inharmonicity of the on-site sound is reduced, and the sound quality of the operation sound of the rotating machine 1 is improved.

[0036] Based on the graph in FIG. 5, the anti-phase sound generator 7 generates an anti-phase sound having an opposite phase to the sound component of the first peak frequency f1 or the second peak frequency f2 when the ratio of the frequency difference to the critical bandwidth is within a range of 0.05 to 0.55 (approximately a dissonance of 0.5 or more), preferably within a range of 0.1 to 0.45 (approximately a dissonance of 0.7 or more).

[0037] 6 is a graph showing an example of the result of a frequency analysis performed on field sounds including the operation sound of the rotating machine 1 shown in FIG. 1. In this example, the frequencies of the field sounds include peak frequencies fn, 2fn, and 3fn, which are 1, 2, and 3 times the rotation frequency fn of the rotating machine 1, and further include a peak frequency 2.1fn, which is 2.1 times the rotation frequency fn of the rotating machine 1. The difference D between the peak frequencies 2fn and 2.1fn is smaller than the critical bandwidth C of the peak frequency 2fn. Therefore, the antiphase sound generator 7 reduces either the sound component having the peak frequency 2fn or the sound component having the peak frequency 2.1fn.

[0038] However, when the sound component with the peak frequency 2fn is reduced, the remaining frequencies are fn, 2.1fn, and 3fn. The sound components with these frequencies are not consonant, and there is a possibility that the listening comfort will not be improved. In contrast, when the sound component with the peak frequency 2.1fn is reduced, the remaining frequencies are fn, 2fn, and 3fn. The ratio of these frequencies is 1:2:3, and the sound components with the frequencies fn, 2fn, and 3fn are highly consonant. As a result, the listening comfort of the on-site sound is improved.

[0039] Therefore, in one embodiment, the antiphase sound generator 7 is configured to select the frequency of the sound component to be reduced so that the multiple sound components in the on-site sound remaining after the sound components are reduced become consonant. A consonant sound is a sound in which two or more sounds are in harmony and is a sound that feels comfortable when heard by a person. Examples of consonant sounds include chords consisting of only a perfect first, a perfect octave, a perfect fifth, a perfect fourth, a major and minor third, or a major and minor sixth.

[0040] 6, the operation control unit 20 of the antiphase sound generator 7 selects the peak frequency 2.1fn so that the frequencies of the sound components remaining after reducing the sound components are fn, 2fn, and 3fn. Then, the operation control unit 20 issues a command to the sound source 8 to generate an antiphase sound having an antiphase phase to the sound component of the peak frequency 2.1fn. Such an antiphase sound generating operation improves the consonance of the on-site sound.

[0041] Fig. 7 is a graph showing another example of the results of frequency analysis performed on field sounds including the operation sound of the rotating machine 1 shown in Fig. 1. In this example, the frequencies of the field sounds include peak frequencies fn, 2fn, and 3fn that are 1, 2, and 3 times the rotational frequency fn of the rotating machine 1, and further include peak frequencies 3fm, 4fm, 5fm, and 6fm that are 3, 4, 5, and 6 times the rotational frequency fm of another rotating machine adjacent to the rotating machine 1.

[0042] The difference D1 between the peak frequencies 2fn and 3fm is smaller than the critical bandwidth C1 of the peak frequency 2fn, and the difference D2 between the peak frequencies 3fn and 4fm is smaller than the critical bandwidth C2 of the peak frequency 2fn. Therefore, the antiphase sound generator 7 reduces either the sound component of the peak frequency 2fn or the sound component of the peak frequency 3fm, and further reduces either the sound component of the peak frequency 3fn or the sound component of the peak frequency 4fm.

[0043] As described above, the operation control unit 20 of the antiphase sound generator 7 is configured to select the frequency of the sound component to be reduced so that the multiple sound components in the on-site sound remaining after the sound components are reduced are consonant. In the example shown in FIG. 7, the operation control unit 20 selects the peak frequencies 3fm and 3fn so that the frequencies of the sound components remaining after the sound components are reduced are fn, 2fn, 4fm, 5fm, and 6fm. Then, the sound source 8 reduces the sound components of the peak frequencies 3fm and 3fn by generating an antiphase sound having an opposite phase to the sound components of the peak frequencies 3fm and 3fn. The ratio of the frequencies fn and 2fn of the remaining sound components is 1:2, and the sound components having these frequencies fn and 2fn have high consonance. Similarly, the ratio of the frequencies 4fm, 5fm, and 6fm of the remaining sound components is 4:5:6, and the sound components having the frequencies 4fm, 5fm, and 6fm have high consonance. As a result, the overall listening comfort of the on-site sound is improved.

[0044] In one embodiment, the antiphase sound generator 7 stores a combination of a plurality of frequencies constituting a consonant tone in the storage device 20a. The combination of a plurality of frequencies constituting a consonant tone is set in advance and input to the operation control unit 20 via the input device 21. Examples of the combination of a plurality of frequencies constituting a consonant tone include a combination of frequencies fn, 2fn, and 3fn, and a combination of frequencies 4fn, 5fn, and 6fn (fn is the rotation frequency of the rotating machine 1). In the case where there is another rotating machine adjacent to the rotating machine 1, the combination of a plurality of frequencies constituting a consonant tone may further include a combination of frequencies fm, 2fm, and 3fm, and a combination of frequencies 4fm, 5fm, and 6fm (fm is the rotation frequency of the adjacent rotating machine).

[0045] The operation control unit 20 of the antiphase sound generator 7 is configured to select the frequency of the sound component to be reduced so that the multiple sound components remaining after the sound components are reduced have a combination of multiple frequencies. In the example shown in Fig. 6, the peak frequency 2.1fn is selected, and in the example shown in Fig. 7, the peak frequencies 3fm and 3fn are selected.

[0046] The operating sound of the rotating machine 1 may differ depending on the model of the rotating machine 1. As a result, the combination of frequencies of the sound components that make up the consonance may also differ. Therefore, the operation control unit 20 predetermines the combination of the multiple frequencies based on the model of the rotating machine. A plurality of combinations corresponding to a plurality of models of the rotating machine may be stored in the storage device 20a. Each combination includes a plurality of frequencies of a plurality of sound components that make up the consonance. A plurality of combinations corresponding to a plurality of models of the rotating machine are input to the operation control unit 20 via the input device 21. According to this embodiment, the frequency of the sound component to be reduced is determined based on the model of the rotating machine 1, so that a consonance that is characteristic of the rotating machine 1 is generated. As a result, the listening comfort can be improved for a plurality of models.

[0047] In one embodiment, the antiphase sound generator 7 may repeat the above-mentioned antiphase sound generating operation. That is, the antiphase sound generator 7 may repeat the following operations: acquiring a site sound from the microphone 14, performing a frequency analysis on the site sound, calculating a difference between a first peak frequency and a second peak frequency included in the site sound, determining the first peak frequency, the second peak frequency, the average frequency of the first peak frequency and the second peak frequency, or the critical bandwidth of the frequency between the first peak frequency and the second peak frequency, and generating an antiphase sound having an antiphase phase with respect to the sound component of the first peak frequency or the second peak frequency when the difference is smaller than the critical bandwidth. By repeating the antiphase sound generating operation, even when the rotation frequency changes due to a load fluctuation of the rotating machine 1 or the like, the antiphase sound generator 7 can reduce the dissonance of the site sound by generating an antiphase sound based on the rotation frequency. The cycle of repeating the antiphase sound generating operation may be set to match the frequency of changes in the sound, such as a load fluctuation of the rotating machine 1, or may be arbitrarily performed when other equipment is operated or when the user feels a change in the sound.

[0048] In each of the above-described embodiments, the antiphase sound generator 7 is configured to reduce the target sound component by generating an antiphase. In one embodiment, the sound quality improving device 6 may further include, in addition to the antiphase sound generator 7, a sound absorbing material that can selectively absorb only sounds having the frequency of the sound component to be reduced. An example of the sound absorbing material is an acoustic metamaterial.

[0049] The above-described embodiments have been described for the purpose of enabling a person having ordinary skill in the art to practice the present invention. Various modifications of the above-described embodiments are naturally possible for a person skilled in the art, and the technical idea of ​​the present invention can be applied to other embodiments. Therefore, the present invention is not limited to the described embodiments, but is to be interpreted in the broadest scope according to the technical idea defined by the claims. [Explanation of symbols]

[0050] 1 Rotating Machinery 3 Rotor 5. Bearings 6 Sound quality improvement device 7. Antiphase Sound Generator 8. Sound Source 10 Foundations 12 Bearing holder 14 Microphone 15 Sound Wave Generator 16 Amplifier 17 Speaker 20 Motion control section 21 Input Devices 25 Reference Microphone

Claims

1. A sound quality improvement device for eliminating discordant sounds from rotating machinery, comprising: A microphone for collecting on-site sounds including the operation sounds of the rotating machine; The present invention includes an antiphase sound generator that reduces the inharmonicity of the on-site sound by reducing any one of a plurality of sound components contained in the on-site sound, The antiphase sound generator includes: Acquire the on-site sound from the microphone; performing a frequency analysis on the on-site sound; Calculating a difference between a first peak frequency and a second peak frequency included in the on-site sound; determining a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency; A sound quality improving device configured to reduce the sound component of the first peak frequency or the second peak frequency by generating an anti-phase sound having an opposite phase to the sound component of the first peak frequency or the second peak frequency when the difference is smaller than the critical bandwidth.

2. 2. The sound quality improving device of claim 1, wherein the antiphase tone generator is configured to generate the antiphase tone when a ratio of the difference to the critical bandwidth is within a range of 0.01 to 0.

55.

3. The sound quality improving device according to claim 1, wherein the antiphase sound generator is configured to select the first peak frequency or the second peak frequency, which is a frequency of the sound component to be reduced, so that a plurality of sound components in the on-site sound remaining after the sound components are reduced become consonant.

4. The antiphase sound generator has a storage device that stores a combination of a plurality of frequencies that constitute a consonant sound, 4. The sound quality improving device according to claim 3, wherein the antiphase sound generator is configured to select the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, so that the multiple sound components remaining after reducing the sound components have a combination of the multiple frequencies that constitute the consonant sound.

5. The sound quality improving device according to claim 4 , wherein the combination of the plurality of frequencies is determined based on a model of the rotating machine.

6. The antiphase sound generator includes: acquiring the scene sound from the microphone; performing a frequency analysis on the in-situ sounds; Calculating a difference between a first peak frequency and a second peak frequency included in the on-site sound; determining a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency; and The sound quality improving device according to claim 1 , configured to repeatedly generate an anti-phase sound having an anti-phase to the sound component of the first peak frequency or the second peak frequency when the difference is smaller than the critical bandwidth.

7. A sound quality improvement method for removing discordant sounds from rotating machinery, comprising the steps of: Collecting field sounds including the operating sounds of the rotating machine with a microphone; Executing an antiphase sound generating operation to reduce the inharmonicity of the on-site sound by reducing any one of a plurality of sound components contained in the on-site sound; The antiphase sound generating operation is Acquire the on-site sound from the microphone; performing a frequency analysis on the on-site sound; Calculating a difference between a first peak frequency and a second peak frequency included in the on-site sound; determining a critical bandwidth of the first peak frequency, the second peak frequency, an average frequency of the first peak frequency and the second peak frequency, or a frequency between the first peak frequency and the second peak frequency; A sound quality improvement method comprising: when the difference is smaller than the critical bandwidth, generating an anti-phase sound having an opposite phase to the sound component of the first peak frequency or the second peak frequency, thereby reducing the sound component.

8. The sound quality improving method according to claim 7, wherein the antiphase sound is generated when the ratio of the difference to the critical bandwidth is within a range of 0.01 to 0.

55.

9. The sound quality improving method according to claim 7, wherein the first peak frequency or the second peak frequency, which is a frequency of the sound component to be reduced, is selected so that a plurality of sound components in the on-site sound remaining after the sound component is reduced become consonant.

10. 10. The sound quality improving method according to claim 9, wherein the first peak frequency or the second peak frequency, which is the frequency of the sound component to be reduced, is selected so that the plurality of sound components remaining after reducing the sound component have a combination of a plurality of preset frequencies that constitute a consonant sound.

11. The sound quality improving method according to claim 10, wherein the combination of the plurality of preset frequencies is determined based on a model of the rotating machine.

12. The sound quality improving method according to claim 7, further comprising repeating the antiphase sound generating operation.

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