CN110401902A - An active noise reduction system and method - Google Patents

Abstract

An active noise reduction system, comprising: multiple groups of noise collection modules, speaker modules, and distance measurement modules, wherein each group of noise collection modules, speaker modules, and distance measurement modules is arranged in a plurality of pre-defined areas of the site to be measured One of them, the noise collection module of the group, is used to collect environmental noise and form a noise signal; the loudspeaker module of the group is used to generate and play the anti-phase noise of the noise signal collected by the noise collection module of the group; A ranging module of one group is used to collect real-time images of people in the site to be measured, recognizes people's positions and calculates the real-time distance between the loudspeaker module and people; an analysis module is used to analyze the noise collection modules of each group Noise and distance information of the ranging module; a control module, used to control the loudspeaker module to send anti-phase noise according to the information input by the analysis module.

Description

An active noise reduction system and method

technical field

The invention relates to the field of living environment, in particular to an active noise reduction system.

Background technique

With the improvement of living standards, people have higher and higher requirements for the living environment, not only requiring the living space to be neat and clean, but also requiring the living environment to be free from noise pollution. According to the allowable indoor noise standards for residential buildings formulated by the Ministry of Construction, the noise limit for bedrooms and study rooms is a maximum of 45 decibels during the day and a maximum of 35 decibels at night. However, the environmental protection department does not use this as a basis for law enforcement. The reason is that the standard was not formulated by the environmental protection department. Indoor noise cannot be divided into five categories like outdoor noise, but can only be classified into one or two categories, because compared with outdoors, indoors should be a quiet environment to ensure that residents can live comfortably and at ease. Therefore, the indoor noise standard may be reduced by 10 decibels from the outdoor Class 0 standard, with a maximum of 40 decibels during the day and a maximum of 30 decibels at night. But for ordinary people, it is still difficult to fall asleep living in a bedroom below the above-mentioned standards, especially for the elderly and children.

For houses facing the street, heavy traffic on the road is a daily trouble for indoor life. Many people want a good indoor environment, and many people take passive noise reduction measures, such as using windows with strong sound insulation effects, and hanging around the windows with sound insulation effects Curtains, green plants that can reduce noise, etc. However, these measures can only passively reduce noise pollution, but cannot completely eliminate noise. For residents who are close to large-scale electrical equipment or rotating machinery, the noise is generally higher than the national standard requirements. At the same time, the housing structure is stimulated by external equipment and will also generate a lot of low-frequency noise. It is difficult for these noises to be effective with the above-mentioned sound insulation measures. Many elderly people are unable to fall asleep and complain about it.

In order to actively eliminate noise, people invented the technology of "active noise reduction". Its principle is: all sounds are composed of a certain spectrum, if you can find a sound whose spectrum is exactly the same as the noise to be eliminated, but the phase is just opposite (180° difference), you can completely cancel the noise . The key is how to get that noise-cancelling sound. The practical method is to start from the noise source itself and try to invert the phase of the original noise through the electronic circuit. From this point of view, the technology of active noise reduction is actually "fighting poison with fire". The above method has been widely used in automobiles, earphones, etc., and is mainly used to reduce noise in fixed points and fixed environments.

The principle of the current active noise reduction technology is divided into three steps: first, the microphone hears the noise; then, the control circuit analyzes the noise characteristics, and orders the speaker to generate a sound wave that is equal in size to the noise and has a phase difference of 180 degrees; finally, the generated sound wave and the noise Superposition makes the two exactly offset cleanly. From the perspective of the realization of the noise reduction function, active noise reduction is divided into three forms: feedforward, feedback, and compound (feedforward + feedback). If you look at active noise-canceling headphones, the realization of feed-forward requires placing a microphone on the outside of the earmuffs on both sides, and the feedback is to place a microphone on the inside of the earmuffs on both sides, and the composite type is one inside and outside the earmuffs, that is, the entire Headphones with four microphones. From the perspective of noise reduction effect only, the effect of compound noise reduction must be stronger than that of single feedforward or single feedback, but its cost and technical realization will be higher and more difficult.

However, there is not yet a particularly good method for noise reduction in an environment such as a bedroom with large spaces, multiple stimuli, and complex audiences.

Contents of the invention

(1) Technical problems to be solved

The present invention proposes an active noise reduction system and method to at least partially solve the above-mentioned problems:

(2) Technical solutions

According to one aspect of the present invention, an active noise reduction system is provided, including: multiple groups of noise collection modules, speaker modules and distance measurement modules, wherein each group of noise collection modules, speaker modules and distance measurement modules is arranged on a waiting One of the pre-delineated multiple areas of the measurement site, the noise collection module of this group is used to collect environmental noise and form noise signals; the speaker module of this group is used to generate and play the noise collected by the noise collection module of this group The noise of the anti-phase noise of the noise signal; the ranging module of this group is used to collect the real-time image of the person in the site to be measured, recognize the position of the person and calculate the real-time distance between the loudspeaker module and the person; an analysis module uses It is used to analyze the noise of the noise collection modules of each group and the distance information of the ranging module; a control module is used to control the speaker module to send anti-phase noise according to the information input by the analysis module.

In a further solution, the speaker module includes: a DSP unit electrically connected to the control module for generating anti-phase noise; a power amplifier circuit for amplifying the anti-phase noise according to a set power A plurality of loudspeakers are electrically connected with the power amplifier circuit, and are used to play the large reverse noise after sending out, wherein the DSP unit adopts FXLMS (Filtered-X Least-Mean-Square, feed-forward X-filtering least mean square Algorithm) algorithm produces the digital signal with the same frequency and reverse of the noise, and the FXLMS algorithm increases the influence of the secondary channel on the basis of the basic LMS (Least-Mean-Square, least mean square algorithm) algorithm, so The secondary path includes the digital-to-analog converter in the speaker module, the reconstruction filter, the power amplifier circuit, the channel from the speaker to the microphone device, the pre-amplification, the anti-aliasing filter and the analog-to-digital converter.

In a further solution, a noise threshold is set in the analysis module, and when the noise power input by the noise collection module is greater than the threshold, the analysis process is started, otherwise, it enters a standby state.

In a further solution, the control module, the analysis module, the noise collection module, the loudspeaker module and the ranging module are connected through an Ethernet network and work in the same network segment.

According to another aspect of the present invention, a method for active noise reduction is provided, including:

The site to be measured is divided into areas according to the set number, and a noise collection module, a distance measuring module and a loudspeaker module are placed in each area;

The ranging module collects real-time images of people in the area, identifies the person's position and measures the real-time distance between the loudspeaker and the human ear;

The noise collection module collects noise information in the area;

The distance measurement module and the noise collection module transmit the distance information and noise information in the area to the analysis module;

The analysis module is used to analyze the measurement results of each area. After obtaining the real-time data of the person, it calculates and obtains the information of the first time when the sound wave generated by the loudspeaker reaches the human ear, and transmits this information to the control system;

The control system calculates the corresponding anti-phase noise signals for each area, and sends them to the area speaker modules for playback to offset the noise and achieve the purpose of noise reduction.

In a further solution, the noise collection module collects noise information in the area including frequency, phase and power of the noise.

In a further solution, the analysis module is used to analyze the measurement results of each area, and first judge whether the noise exceeds the preset noise threshold, and if so, start the analysis process.

(3) Beneficial effects

The present invention utilizes the principle of multi-point partitioning to divide the site to be measured into set areas, and install a distance measuring module, a noise collecting module and a loudspeaker module in the corners of the area to generate an anti-phase noise signal corresponding to the noise, forming a three-dimensional surround The sound signal, so that the external noise transmitted to the human ear and the sound signal emitted by the speaker are exactly equal in size and opposite in phase, and can cancel each other out, achieving a better noise reduction effect and effectively realizing active noise reduction.

At the same time, the present invention avoids a group of noise reduction modules in the prior art, because the positions of people in the area are different, the sound signal from the loudspeaker and the path of the external noise to the human ear are different, and the phase of the sound signal and the noise is not the same. Just the opposite, causing the problem of increased noise.

In addition, the present invention can measure the noise transmitted to the whole room, analyze and judge whether the noise exceeds the preset noise value, and if the noise exceeds the limit value, the noise reduction system can be turned on, avoiding the noise when the noise is not enough to disturb the activities of people in the room. The noise reduction system is turned on to prevent the waste of resources.

Description of drawings

Fig. 1 is a functional block diagram of an active noise reduction system according to an embodiment of the present invention.

Fig. 2 is a flowchart of an active noise reduction method according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

In the present invention, "disposed on" or "attached to" is used to include a direct contact relationship with a single or multiple components. Moreover, the ordinal numbers used in the specification and claims, such as "first", "second", "number one" or "number two", are used to modify the components claimed for protection, which do not themselves contain and represent the Parts have any previous ordinal numbers, nor do they imply the order of one part with another or in terms of manufacturing methods, and these ordinal numbers are used only to enable a part with a certain designation to be related to another part with the same designation Can make a clear distinction.

There is not yet a particularly good method for noise reduction in a bedroom with a large space, multiple stimuli, and a complex audience. Because when people are active in the room, if there is only one set of noise reduction modules in the room, as the position of the person in the room changes continuously, the sound signal from the microphone and the external noise will be transmitted to the human ear through different paths. The phase of the sound signal in the human ear is not exactly opposite to the noise, which may increase the noise, and the purpose of removing the noise cannot be achieved, but the phase of the noise and the sound wave emitted by the speaker is not exactly opposite, and the noise cannot be exactly offset, and the noise may even be increased. If the intensity is high, this active noise reduction method will be greatly reduced. For this reason, based on the principle of multi-point partition, the present invention designs an active noise reduction system and method for living environment with good noise reduction effect, and contributes to improving the living environment.

The embodiment of the present invention discloses an active noise reduction system. Fig. 1 is a functional block diagram of an active noise reduction system according to the embodiment of the present invention. As shown in Fig. 1, it includes: multiple groups of noise collection modules, speaker modules and distance measuring module, wherein each group of noise collection module, loudspeaker module and distance measurement module is arranged in one of the pre-delineated multiple areas of the site to be tested, and the group of noise collection modules is used to collect environmental noise and form a noise signal , in this embodiment, each noise collection module adopts two microphones in opposite directions, which can collect environmental noise in real time, and output noise signals to the analysis module, and the output noise signal size can reflect the size of the noise in the site to be measured; The loudspeaker module of this group is used for producing and broadcasting the noise of the anti-phase of the noise signal that the noise collection module of this group collects; Calculate the real-time distance between the loudspeaker module and people; an analysis module, used to analyze the noise of the noise collection modules of each group and the distance information of the ranging module, in this embodiment, the analysis module outputs the noise collection module Compared with the preset noise threshold, when the ambient noise is large and the output noise is greater than the noise threshold, the noise reduction switch circuit is turned on at this time, and the active noise reduction device starts to work to realize the noise reduction in the site to be tested. Noise reduction: when the ambient noise is small, the noise reduction switch circuit is cut off, and the active noise reduction device stops working. Therefore, through the noise collection module and the analysis module, the active noise reduction device can be controlled to work or stop according to the size of the noise, and not only It can realize active noise reduction in a noisy environment, and can also turn off the active noise reduction device in a low-noise environment to save power resources. In addition, the analysis module can be based on the distance and real-time driving of people in the site to be tested. The data is calculated to obtain the first time information when the sound waves generated by different speakers reach the human ear. According to the time information, the corresponding generated noise signals can be sent to the corresponding speaker modules for playback. Due to the distance between each group of speakers and people different, the phase of the generated anti-phase noise signal will also be different; a control module, used to control the loudspeaker module to send anti-phase noise according to the information input by the analysis module.

Wherein, the loudspeaker module includes: a DSP unit electrically connected to the control module for generating anti-phase noise, each DSP unit converts the noise audio signal into a reverse noise digital signal after calculation and inputs the corresponding The power amplifier circuit of the present invention, in the exemplary embodiment of the present invention, the output terminal of control module is connected with four DSP units, and DSP unit is the digital signal processing unit, burns FXLMS algorithm program in the DSP unit, utilizes this algorithm to process simple plane wave audio frequency Signal produces the digital signal of same frequency reverse; Described FXLMS algorithm has considered the influence of the S (z) of secondary channel promptly on the basis of basic LMS algorithm, and concrete secondary channel comprises the digital-to-analog converter in the loudspeaker, A reconstruction filter, a power amplifier circuit, a channel between the loudspeaker and the microphone device, a preamplifier, an anti-aliasing filter and an analog-to-digital converter; a power amplifier circuit, which is used to amplify the anti-phase noise according to a set power; A plurality of loudspeakers are electrically connected with the power amplifier circuit, and are used for playing amplified reverse noise.

In an exemplary embodiment of the present invention, the site to be measured is divided into four areas, and a distance measuring module, a noise collection module, and a loudspeaker module are deployed at the corners of each area, wherein each loudspeaker module includes a DSP unit , a power amplifier circuit and two loudspeakers. In addition, the analysis module and control module can be deployed anywhere in the venue or outside the venue.

In this embodiment, the control module, the analysis module, the noise collection module, the loudspeaker module and the ranging module are connected through an Ethernet network and work in the same network segment.

The embodiment of the present invention also provides an active noise reduction method using the system. Figure 2 is a flowchart of the active noise reduction method in the embodiment of the present invention, as shown in Figure 2, including:

The site to be measured is divided into areas by a set number, and a noise collection module, a distance measuring module and a loudspeaker module are placed in each area; in an example embodiment of the present invention, the site to be measured is divided into four areas, and each A ranging module, a noise collection module, and a loudspeaker module are deployed in the corners of the area, wherein each loudspeaker module includes a DSP unit, a power amplifier circuit and two loudspeakers. In addition, the analysis module and the control module can be deployed in anywhere on or off the Venue;

As the position of the person changes, the four groups of ranging modules collect real-time images of people moving in the venue, can identify the position of the person and measure the real-time distance between the four groups of speakers and the human ear;

Four groups of noise collection modules distributed in the corners of the site are used to collect noise inside the site and measure the noise transmitted from the outside to different positions inside the site;

The four sets of ranging modules and the noise collection module transmit the measurement results to the analysis module, and the analysis module is used to analyze the four sets of different measurement results to determine whether the noise exceeds the preset noise threshold, and if it exceeds, the system will be turned on; at the same time After obtaining the real-time data of human activities, calculate and obtain the first time information of the sound waves generated by the four groups of speakers reaching the human ear;

According to the noise data input by the noise collection module and the first time information generated by the ranging module, the control module generates four sets of corresponding anti-phase noise signals, which are sent to the corresponding speaker modules for playback, so that a stereo surround sound can be formed Signal; the external noise transmitted to the human ear and the sound signal from the speaker are exactly equal in size and opposite in phase when they are at the human ear, and can cancel each other out to achieve a better noise reduction effect and effectively achieve active noise reduction.

When there are multiple people in a certain area of the site to be tested at the same time, the optical ranging system can identify and collect real-time images of multiple people moving in the site to be tested, and measure the real-time distance between different people and the speaker according to the position of each person Measurement. The analysis module and the control module can preferentially select the two groups of noise reduction systems closest to each person and the two groups of systems farthest away from each person for noise reduction according to different distances. In order to achieve better noise reduction effects, multiple Set up several groups of noise reduction systems so as not to affect the noise reduction effect when there are many people.

Through the above statements, aiming at the problems and shortcomings in the prior art, the embodiment of the present invention provides an active noise reduction system and an active noise reduction method using the system. Divided into a set area, install a distance measuring module, a noise collection module and a speaker module in the corner of the area to generate an anti-phase noise signal corresponding to the noise, forming a stereo surround sound signal, so that the external noise transmitted to the human ear and The sound signals emitted by the speakers are exactly equal in size and opposite in phase when they are at the human ear, and can cancel each other out to achieve a better noise reduction effect and effectively achieve active noise reduction. At the same time, the present invention avoids a group of noise reduction modules in the prior art, because the positions of people in the area are different, the sound signal from the loudspeaker and the path of the external noise to the human ear are different, and the phase of the sound signal and the noise is not the same. Just the opposite, causing the problem of increased noise. In addition, the present invention can measure the noise transmitted to the entire site to be tested, and analyze and judge whether the noise exceeds the preset noise value. If the noise exceeds the limit value, the noise reduction system can be turned on, avoiding that the noise is not enough to disturb the site to be tested. When people are active, the noise reduction system is turned on to prevent waste of resources.

The specific embodiments described above have further described the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above descriptions are only specific embodiments of the present invention, and are not intended to limit the present invention. Within the spirit and principles of the present invention, any modifications, equivalent replacements, improvements, etc. should be included in the protection scope of the present invention.

Claims (10)

1. An active noise reduction system comprising: A plurality of groups of noise collection modules, loudspeaker modules and distance measuring modules, wherein each group of noise collection modules, loudspeaker modules and distance measurement modules is arranged in one of a plurality of areas pre-defined in the site to be measured, and the noise collection module of this group The module is used to collect environmental noise and form a noise signal; the loudspeaker module of this group is used to generate and play the noise in antiphase with the noise signal collected by the noise collection module of this group; the ranging module of this group is used to collect Real-time images of people in the site to be tested, identifying the position of people and calculating the real-time distance between the loudspeaker module and people; An analysis module, used to analyze the noise of the noise collection modules of each group and the distance information of the ranging module; A control module, used for controlling the loudspeaker module to send anti-phase noise according to the information input by the analysis module. 2. The system according to claim 1, wherein said speaker module comprises: A DSP unit, electrically connected with the control module, for generating anti-phase noise; A power amplifier circuit, used to amplify the anti-phase noise according to the set power; A plurality of loudspeakers are electrically connected with the power amplifier circuit, and are used for playing amplified reverse noise. 3. The system according to claim 1, wherein a noise threshold is set in the analysis module, and when the noise power input by the noise collection module is greater than the threshold, the analysis process is started. 4. The system according to claim 1, said noise collection module collects information including frequency, phase and power of noise. 5. The system according to claim 2, wherein the FXLMS algorithm is used in the DSP unit to generate a digital signal with the same frequency as the noise and reversed. 6. The system according to claim 5, wherein the FXLMS algorithm increases the influence of the secondary channel on the basis of the LMS algorithm, and the secondary channel includes a digital-to-analog converter in the speaker module, a reconstruction filter, Power amplifier circuit, channel from speaker to microphone unit, pre-amplification, anti-aliasing filter and analog-to-digital converter. 7. The system according to claim 2, wherein the control module, the analysis module, the noise collection module, the loudspeaker module and the ranging module are connected through an Ethernet network and work in the same network segment. 8. An active noise reduction method applying the system according to any one of claims 1-7, comprising: The site to be tested is divided into areas according to the set number, and a noise collection module, a distance measurement module and a speaker module are placed in each area; The ranging module collects real-time images of people in the area, recognizes the position of the person and measures the real-time distance between the speaker and the human ear; The noise collection module collects noise information in the area; The distance measurement module and the noise collection module transmit the distance information and noise information in the area to the analysis module; The analysis module is used to analyze the measurement results of each area. After obtaining the real-time data of the person, it calculates and obtains the information of the first time when the sound wave generated by the speaker reaches the human ear, and transmits this information to the control system; The control system calculates the corresponding anti-phase noise signals for each zone, and sends them to the zone speaker modules for playback respectively. 9. The method according to claim 8, wherein the noise information in the area collected by the noise collection module includes frequency, phase and power of the noise. 10. The method according to claim 8, wherein the analysis module is used to analyze the measurement results of each area, firstly judge whether the noise exceeds a preset noise threshold, and if so, start the analysis process.