JPH0313998A - Electronic sound deadening system - Google Patents

Abstract

PURPOSE:To deaden noises in a three-dimensional sound field by providing plural additional sound generating means, supplying input information to plural driving signal generating means in common and controlling sound pressure according to the information of a single error microphone. CONSTITUTION:The error microphone 24 is arranged in an area where a noise is to be deadened, detects a noise from a press machine 20 and noises after sound wave interference with additional sounds from respective speakers 40A, 40B...40N, and outputs error signals indicating the noises to respective controllers 30A, 30B...30N. The respective controllers 30A, 30B...30N generate driving signals according to propagation functions, detection signals X, and error signals E which are supplied respectively and output them to corresponding speakers 40A, 40B...40N. Consequently, the additional sounds radiated from the speakers 40A, 40B...40N operate to decrease the output of the error microphone 24 and the wave fronts are superposed well to deaden noises in a three-dimensional sound field over a wide area.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an electronic silencing system, and particularly to a system for emitting additional sound having the same sound pressure and opposite phase to noise in a three-dimensional sound field propagating from a sound source. , relates to an electronic silencing system that forcibly produces a silencing effect by sound wave interference.

[Conventional technology]

Regarding this type of electronic muffling system, the present applicant has already disclosed a system configuration for practical use in Japanese Patent Laid-Open Publication No. 164400/1983.

Figure 2 is a block diagram of a conventional electronic silencing system.
This system is mainly used to muffle noise propagating through pipeline systems such as ducts and pipes, and includes a sensor microphone 2 that detects noise within the pipeline 1, and a sensor microphone 2 that detects noise in the pipeline 1.
Additional sound generating means (speaker) provided downstream of the noise source to generate a sound wave having the same sound pressure and opposite phase to the noise.
4, an error microphone 3 that is installed downstream of the speaker 4 and detects the noise inside the pipe 1 at this position, the pipe 1, the sensor microphone 2, the speaker 4, and the error microphone 3.
a control unit 16 that calculates the overall sound wave transfer function of the system configured by the control unit 16; and a drive that is applied to the speaker 4 so that the output of the error micro 3 is minimized based on the transfer function specified by the control unit 16. A driving signal generating means (digital filter) 15 for generating a signal is provided.

In Fig. 2, 11 is an addition circuit that inputs the detection signal from the sensor microphone 2 into a positive input, inputs the detection signal from the error microphone 3 as a negative input, and adds the rain detection signal, and 12 is an addition circuit. An A/D converter 13 converts the output of the circuit 11 into A/D and outputs it to the digital filter 15 and the control unit 21, respectively. 13 is a D/A converter that converts the output of the digital filter 15 into A/D and outputs it to the speaker 4. The converting section 14 is an A/D converting section that A/D converts the detection signal from the error microphone and outputs the result to the control section 16.

[Problem to be solved by the invention]

By the way, the above-mentioned conventional electronic silence system includes one sensor microphone 2, one error microphone 3, one speaker 4, a digital filter 15, and a control circuit. This is a monopole system composed of one controller 10 including a B section 16 and the like, and is used to muffle noise in a one-dimensional sound field passing through the pipe 1.

On the other hand, the wavefront of noise in a three-dimensional sound field is complex, and in the field to which the monopole system described above is applied, it is possible to mute the sound at a local point in space (specifically, near the error microphone); It is difficult to expand the silencing area.

One way to solve this problem is to combine multiple monopole systems.

However, the method of expanding the silencing area by operating a plurality of monopole systems independently does not provide a sufficient silencing effect, but rather often increases the sound pressure around the error microphone.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic muffling system that can satisfactorily muffle noise in a three-dimensional sound field over a wide area.

[Means to solve problems]

In order to achieve the above object, the present invention generates a sound wave having an opposite phase and the same sound pressure as a propagating sound wave from a noise source in a sound wave propagation path, and generates a sound wave at a predetermined position in the propagation path. In an electronic silencing system that performs silencing by sound wave interference, a noise information detection means is arranged closer to the noise source than the predetermined position in the propagation path, and detects noise information indicating the noise of the noise source and converts it into an electrical signal. , is provided around an area to be silenced between the position where the noise information detection means is installed in the propagation path and the predetermined position, and emits a sound wave for canceling the propagating sound wave from the noise source at the predetermined position. A plurality of additional sound generating means are provided between the installation position of the additional sound generating means and the predetermined position or at the predetermined position, detecting the propagating sound waves from the additional sound generating means and the noise source, and generating electricity. one error microphone for converting into a signal; a control means for determining a comprehensive sound wave transfer function of a system constituted by the propagation path, the noise information detection means, the additional sound generation means, and the error microphone for each additional sound generation means; , to the corresponding additional sound generating means so that the output of the error microphone is minimized based on the transfer function for each additional sound generating means specified by the control means and the output signals of the noise information detecting means and the error microphone. The present invention is characterized by comprising a plurality of drive signal generation means for generating drive signals to be applied.

[Effect]

According to the present invention, a plurality of additional sound generation means are arranged around an area to be silenced, and the human power information of the plurality of drive signal generation means that output drive signals to each of these additional sound generation means is shared. , each additional sound generating means is 1
The system is configured to comprehensively control the sound pressure based on information from the book's error microphone, thereby expanding the silencing area.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the electronic silencing system according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram showing an embodiment of an electronic silencing system according to the present invention. This electronic silencing system includes a sensor microphone 22, an error microphone 24, a plurality of controllers 30A, 30B, . . . 3ON1, and a plurality of speakers 40A, 40B, . . . 4ON.

In addition, each controller 30A130B1...3ON is
Since each controller has the same configuration as the controller 10 shown in FIG. 2, detailed explanation thereof will be omitted here.

In FIG. 1, the noise source is a press machine 20, and the noise from the hammer 2OA of this press machine 20 propagates in a three-dimensional space. The sensor microphone 22 is arranged near the press machine 20, and detects noise from the press machine 20 and sends an electric signal (detection signal/signal) X indicating the noise to each:+n)o
- Output to 30A, 30B1...3ON.

On the other hand, the error microphone 24 is placed in an area where it is desired to mute the noise from the press machine 20 and each speaker 4QA, 4.
The noise after sonic interference with the additional sound from 0B, .

A plurality of speakers 40A, 40B, .

... Generates additional sound to cancel noise based on the drive signal applied from 3ON.

The controllers 30A, 30B, .
... The propagation path of the sound wave is different due to the difference in the arrangement position of the 4ONs, and as a result, the overall transfer function of the sound wave given to the digital filter by the control section is different. Each controller 30A, 30B,...3ON
creates a drive signal based on the given transfer function, detection signal X, and error signal E, and outputs it to the corresponding speakers 40A, 40B, . . . 4ON.

By the way, in order to expand the silencing area, speakers 40A140B1...
The wavefront 42 of the additional sound from the 4ON needs to be superimposed with high precision. In a system that combines multiple monopole systems, each works independently, making it difficult to superimpose wavefronts. However, in the present invention, the sensor microphone 22 and the error microphone 2
4 are common, and speakers 40A, 40B,...
Since all the additional sound emitted from the 4ON acts to reduce the output of the error microphone 24, the wavefronts are effectively superimposed, and the silencing area can be expanded.

Although one sensor microphone 22 is used in this embodiment, a plurality of sensor microphones may be provided corresponding to each speaker 40A, 40B, . . . 4ON.

In addition, detection of noise information is not limited to sensor microphones; for example, a vibration pickup may be used to fix the vibration state of the noise source and detect it indirectly.In short, it is necessary to detect some information that is correlated with the noise. It's fine as long as you can get it.

〔Effect of the invention〕

As explained above, according to the electronic noise reduction system according to the present invention, noise in a three-dimensional sound field can be effectively suppressed over a wide area.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of an electronic silencing system according to the present invention, and FIG. 2 is a block diagram showing an example of a conventional electronic silencing system. 10.30A, 30B, 3ON...controller, 1
5...Digital filter, 16...Control unit,
22...Sensor microphone, 24...Error microphone, 40A, 40B, 4ON...Speaker.

Claims (1)

[Claims] A sound wave is generated that has the opposite phase and the same sound pressure as a propagating sound wave from a noise source in a sound wave propagation path, and the sound is silenced at a predetermined position in the propagation path by the sound wave interference. In the electronic silencing system, the noise information detection means is arranged closer to the noise source than the predetermined position in the propagation path, and detects noise information indicating noise of the noise source and converts it into an electrical signal; a plurality of additional sound units installed around an area to be silenced between the installation position of the noise information detection means and the predetermined position in the noise information detection means and emitting sound waves for canceling the propagating sound waves from the noise source at the predetermined position; generating means; and 1, which is provided between the installation position of the additional sound generating means and the predetermined position or at the predetermined position, and detects the propagating sound waves from the additional sound generating means and the noise source and converts them into electrical signals. a control means for determining a comprehensive sound wave transfer function of a system constituted by the propagation path, the noise information detection means, the additional sound generation means, and the error microphone for each additional sound generation means; Based on the identified transfer function for each additional sound generating means and the output signals of the noise information detecting means and the error microphone, create drive signals to be given to the corresponding additional sound generating means so that the output of the error microphone is minimized. An electronic silencing system characterized by comprising: a plurality of drive signal generating means for generating a plurality of drive signals;