JPH0376500A - Electronic silencing system - Google Patents

Abstract

PURPOSE:To silence only noise without reducing required sound components by using a 1st mechanical electric converting means such as vibration pickup able to detect the vibration of a noise source or the state of rotating operation not through air so as to detect indirectly noise information from the noise source. CONSTITUTION:A vibration pickup 12 detects a waveform of impact and vibration of a press machine 10. An error microphone 16 detects a sound wave after sound wave interference and outputs it to an adaptive control arithmetic circuit 23 as error information E. An FIR adaptive digital filter 21 applies conversion processing to the input information X into a signal with a prescribed amplitude and phase characteristic based on a given filter coefficient. The output signal of the filter 21 is D/A-converted by a D/A converter 27 and outputted to a speaker 14. Thus, the sound wave 30 of noise generated from the press machine 10 and the sound wave 32 being additional sound radiating from the speaker 14 are interfered and the propagation sound wave from press machine 10 is silenced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an electronic silencing system that actively mutes noise in a three-dimensional sound field, and is particularly applicable to stationary noise sources such as presses, compressors, and casting machines. , and relates to an electronic muffling system suitable for muffling noise from a noise source that has a correlation between the state of its operation and the noise generated.

[Conventional technology]

Conventionally, in response to the propagating sound waves propagating in pipes such as air conditioning ducts from noise sources such as air conditioning equipment, sound waves with opposite phases and the same sound pressure are generated, and the sound waves are silenced at a predetermined position in the pipe by the sound wave interference. In order to realize an electronic silencing system that performs
, Japanese Patent Application No. 62-148254, etc. have disclosed specific configurations.

[Problem to be solved by the invention]

However, the need for noise countermeasures is based on pipes (one-dimensional sound field).
In addition, there are many types of noise in three-dimensional sound fields, and active silencing is desired here as well.

By the way, in the case of a three-dimensional sound field, there is a sensor microphone that detects noise information, and a speaker that generates sound waves that are in the opposite phase and have the same sound pressure as the propagating sound waves detected by the sensor microphone. It is essential to take measures against howling that occurs between the two, and the hardware configuration to achieve this is essential. ! There is a problem with becoming a pheasant.

In addition, in a three-dimensional sound field, it is important to distinguish between noise and announcements broadcast from on-premises speakers, etc., and to mute only the noise, but in the case of the sensor microphone mentioned above, it is important to distinguish between noise and announcements broadcast from on-premises speakers, etc., but in the case of the sensor microphone mentioned above, noise and sounds that should not be muted are It is difficult to distinguish between
As a result, there is a problem in that sounds that should not be muted are also reduced.

The present invention has been made in view of these circumstances, and provides an electronic muffler for a three-dimensional sound field that can easily solve the above-mentioned howling problem and can muffle only noise without reducing necessary sounds. The purpose is to provide a system.

[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 the sound wave propagating from a noise source in the propagation path of the sound wave, and generates a sound wave at a predetermined position in the propagation path. In an electronic noise reduction system that performs sound reduction using sound wave interference, the first system detects the state of vibration or rotational motion of a noise source that is correlated with the noise generated by the noise source without using air, and converts it into an electrical signal. and a sound wave provided between the location of the first mechanical and electrical conversion means in the propagation path and the predetermined position for canceling the propagating sound wave from the noise source at the predetermined position. an electromechanical transducer that radiates a noise source; and an electromechanical transducer that is provided between a disposed position of the electromechanical transducer and the predetermined position or at the predetermined position, and that the electromechanical transducer detects a propagating sound wave from the noise source. A second mechanical-electrical converting means converts the output signal into an electrical signal, and the output signal of the first mechanical-electrical converting means is taken in, and the electrical signal is converted so that the silencing amount of the electronic silencing system is maximized based on a given transfer function. Determining a drive signal creation means for creating a drive signal to be given to the mechanical conversion means, a transfer function to be given to the drive signal creation means, and setting control parameters for specifying the transfer function in the drive signal creation means; , a control means for modifying the control parameters according to changes in propagation characteristics of the propagation path and changes in characteristics of the control system.

[Effect]

The present invention is not a closed-loop system in which a speaker and a sensor microphone are acoustically coupled as in conventional electronic muffling systems, but instead of a sensor microphone, it is possible to detect vibration or rotational motion of a noise source without intervening air. The first vibration pickup etc. that can detect
It is configured to be an oven loop system that indirectly detects noise information from a noise source using a machine VT electric conversion means.

As a result, since the first 'a reducing electricity conversion means and the electromechanical conversion means (speaker) are not directly coupled acoustically, there is no problem of howling, and the first electromechanical conversion means is connected to a broadcasting speaker, etc. Since the system does not detect sounds emitted from the system, it does not reduce sounds that should not be muted.

[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.

As shown in the figure, this electronic silencing system is for silencing the noise generated from the press machine 10 in the factory building (three-dimensional sound field), and mainly detects the vibration of the noise source that is between t and the noise. A vibration pickup 12, a speaker 14 that generates additional sound (secondary sound) to cancel noise, an error microphone 16 for evaluating the silencing effect, and a drive signal is output to the speaker 14 based on the outputs of the vibration pickup 12 and error microphone 16. Control device 2
It is composed of 0.

The configuration of the control device 20 is basically disclosed in Japanese Patent Application No. 61-711.
However, since no howling (acoustic feedback) occurs, the digital circuit section is composed of an FIR adaptive digital filter 2i, an FIR digital filter 22, and an adaptive control arithmetic circuit 23.

Now, the noise generated from the press machine 10 is the hammer 10.
A is the impact sound generated when punching a plate material, and the main frequency of the noise is the component of even multiples of the punching period.

The vibration pickup 12 detects the waveform of the impact vibration of the press 10 and sends an electric signal representing the waveform to the amplifier 24 of the control device 20 and the spectrum shavers 25 and 4 via the D/D converter 26, which is correlated with noise. FI as input information
It is output to the R adaptive digital filter 21 and the FIR digital filter 22.

Further, the error microphone 16 detects the sound wave after the sound wave interference, and the amplifier 24, spectrum shaver 25 and A
It is output as error report E to the adaptive control calculation circuit 23 via the /D converter 28.

The FIR digital filter 22 multiplies the input information X by a predetermined transfer function and outputs this to the adaptive control calculation circuit 20. Here, before operating the system, a pseudo signal for driving the speaker 14 is output, and the transfer function is identified based on the pseudo signal and error information E obtained from the error microphone 16.

The adaptive control arithmetic circuit 23 determines a transfer function to be given to the FIR adaptive digital filter 21 based on the input from the FIR digital filter 22 and the error information E so that the error information E is minimized. A filter coefficient, which is a control parameter for specifying, is given to the FIR adaptive digital filter 21.

The FIR adaptive digital filter 21 converts the human power information X into a signal with predetermined amplitude and phase characteristics based on the given filter coefficients.

The output signal of this digital filter 21 is subjected to D/A conversion by a D/A converter 27, and then converted to a spectrum shaver.
25 and the amplifier 24 to the speaker 14.

As a result, the sound waves 30 of the noise generated from the press machine 10 are
and the sound wave 32 of the additional sound (secondary sound) emitted from the speaker 14 cause sound wave interference, and the sound wave propagating from the press 10 is muffled.

In addition, in the figure, 34 is a speaker for public address system,
36 is a sound wave of the sound that is broadcast from the speaker 34;

In the electronic silencing system described above, since the vibration pickup 12 and the speaker 14 are not directly connected acoustically (the vibration pickup 12 does not detect the person attached to the speaker 14), there is no problem of howling. The sound waves 36 of the sound broadcast from the public address speaker 34 are detected by the error microphone 16, but not by the vibration pickup 12, so they become uncorrelated noise for the control device 20, so this electronic muffling system The sound is not muted, which is beneficial for the transmission of audio information.

In this embodiment, the state of vibration of the noise source is detected by the vibration pickup 12, but since it is important to detect the fundamental period of the vibration of the noise source, an optical sensor may also be used instead. It is possible to do so. In short, any device may be used as long as it detects the state of vibration of the noise source without intervening air. Note that the optical sensor has the advantage that it can be used even in environments where there is a large magnetic influence or temperature difference.

〔Effect of the invention〕

As explained above, according to the electronic silencing system according to the present invention, since information correlated with the noise generated from the noise source is detected without intervening air, howling does not occur and the three-dimensional sound field Howling countermeasures are no longer required. Further, it is possible to distinguish between noise and announcements broadcast from a public address speaker or the like, and only the noise can be muted.

[Brief explanation of drawings]

The figure is a system configuration diagram showing an embodiment of an electronic muffling system according to the present invention. DESCRIPTION OF SYMBOLS 10... Press machine, 12... Vibration pickup, 14... Speaker, 16... Error microphone, 20... Control device, 21... FIR adapting digital filter, 22... FI
R digital filter, 23... adaptive control calculation circuit.

Claims (1)

[Scope of Claims] A sound wave is generated that has an 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 by the sound wave interference at a predetermined position in the propagation path. In an electronic silencing system, a first electromechanical conversion means detects, without intervening air, an operating state of a noise source that is correlated with the noise generated from the noise source and converts it into an electrical signal; an electromechanical transducer that is provided between the location of the first electromechanical transducer in the 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 second electromechanical converter provided between the arrangement position of the electromechanical converter and the predetermined position or at the predetermined position, which detects propagating sound waves from the electromechanical converter and the noise source and converts them into electrical signals; The output signal of the converting means and the first mechanical-electrical converting means is taken in, and a drive signal is created to be applied to the electro-mechanical converting means so that the amount of silencing of the electronic silencing system is maximized based on a given transfer function. a drive signal generation means; a transfer function to be given to the drive signal generation means; a control parameter for specifying the transfer function is set in the drive signal generation means; and a control parameter for changing and controlling the propagation characteristics of the propagation path. An electronic silencing system comprising: control means for modifying the control parameters according to changes in system characteristics.