A method and device for adaptive noise reduction

Abstract

The application discloses a kind of self-adapting noise reduction method and noise reduction device, including following process: the noise source of specific environment is collected, and is converted into noise data, the record keeping of noise data is carried out;Analysis processing noise data, determine the A rate coefficient of noise source under environment;Record keeping and send A rate coefficient to adaptive controller, carry out adaptive filtering noise reduction.The application realizes the analysis to specific environmental noise, can evaluate the use effect of protective earmuff, provides direction for protective earmuff improvement, and can grasp the relative relationship of personnel hearing and noise, strong universality, better practicality, easy to popularize and apply, with greater practical value.

Description

Technical Field

[0001] This invention relates to the field of noise reduction, and more specifically, to an adaptive noise reduction method and noise reduction device. Background Technology

[0002] Generally, short-term exposure to noise can cause auditory fatigue and temporary hearing loss; long-term exposure can lead to permanent hearing loss. Noise levels below 80 dB generally do not cause noise-induced hearing loss, levels above 80 dB have varying degrees of impact on hearing, and levels above 95 dB have very serious effects. Prolonged work in high-noise environments without effective protective measures will inevitably lead to permanent and irreversible hearing loss, and even severe occupational deafness. Besides causing deafness, loud noise can also adversely affect the nervous, cardiovascular, digestive, and reproductive systems. Particularly loud noise can also cause neurological disorders, shock, and even endanger life. Because noise easily causes psychological fear and masks alarm signals, it severely affects the alertness and responsiveness of combat personnel.

[0003] Noise protection is a global concern, necessitating the development of hearing aids with active noise cancellation technology. This would address noise protection issues, facilitate communication among users, better meet work requirements, and enhance overall application capabilities. Currently, domestic active noise-canceling headphone technology primarily utilizes analog techniques and a single feedback control method, achieving an average noise reduction of around 10dB. This is sufficient for everyday work environments but cannot meet the demands of increasingly demanding noise conditions. Furthermore, there is a lack of technology for analyzing noise levels inside and outside the earcups when worn, a gap in domestic research. Therefore, there is an urgent need for research into an adaptive noise cancellation and analysis method to create adaptive noise-canceling headphones that can adapt to different environments and noise levels. Summary of the Invention

[0004] 1. Technical problems to be solved

[0005] To address the harm to hearing and physiology caused by various environmental noises, this invention employs an adaptive noise reduction algorithm. Based on the statistical characteristics of the input and output, the algorithm automatically adapts to noise reduction by allowing the input statistical characteristics to change slowly over time during the filtering process. Furthermore, it records the frequency, level, and duration of perceived noise during noise reduction, presenting the noise exposure level. Data analysis of hearing data enables hearing protection, and the analysis of actual noise perception quantifies noise exposure, allowing for evaluation of the effectiveness of protective earmuffs and providing direction for their improvement. It also allows for understanding the relative relationship between hearing and noise, facilitating research on hearing protection. This invention is highly versatile, employing a noise analysis and recording module to analyze environmental noise and implement targeted adaptive noise reduction, avoiding the shortcomings of existing noise-canceling headphones that are not universally applicable in different environments. Therefore, it has good practicality, is easy to promote and apply, and has significant practical value.

[0006] 2. Technical Solution

[0007] To solve the above problems, the present invention adopts the following technical solution.

[0008] An adaptive noise reduction method includes the following steps:

[0009] Collect noise sources in a specific environment, convert them into noise data, and record and save the noise data;

[0010] Analyze and process noise data to determine the A-rate coefficient of noise sources in the environment;

[0011] Record and save the A-rate coefficients and send them to the adaptive controller for adaptive filtering and noise reduction;

[0012] The A-rate coefficient is determined using the following method:

[0013] The noise data is processed in the frequency domain, converting the time-domain signal into a frequency-domain signal to obtain multiple frequency bands of the noise source. The sound pressure level (SPL) of each frequency band is calculated, and the A-rate coefficient is used to represent the final SPL of all frequency bands for displaying the noise data, with the unit being dBA. The formula for calculating the SPL of each frequency band is as follows:

[0014]

[0015] Its A-rate coefficient formula is:

[0016]

[0017] The formula for calculating the final sound pressure level across all frequency bands is:

[0018]

[0019] Furthermore, the adaptive controller adjusts the preset noise reduction weight coefficients according to the A-rate coefficient, and performs adaptive filtering and noise reduction using an adaptive algorithm; the adaptive algorithm uses the following formula:

[0020]

[0021] Where: x(n) is the reference signal; S(z) is the error channel; x'(n) is the filtered secondary signal; y(n) is the secondary signal; and e(n) is the error signal.

[0022] Furthermore, an adaptive noise reduction device employing the aforementioned adaptive noise reduction method includes a pair of earmuffs, with a noise recording and analysis module and a noise reduction module installed inside the earmuffs.

[0023] Furthermore, the noise recording and analysis module includes an acquisition module, an analysis module, a recording module, a display module, a PC communication module, and a battery voltage control module;

[0024] The acquisition module includes a built-in microphone and an external microphone. The built-in microphone is located inside the earcups to collect noise sources within the earcups. The external microphone is located outside the earcups to collect noise sources in specific environments. The acquisition module converts the noise sources into noise data and transmits it to the recording module, analysis module, and noise reduction module. The analysis module determines the A-rate coefficient based on the noise data and sends it to the recording module for A-rate coefficient analysis in specific environments, while also sending it to the noise reduction module. The recording module records the noise data and its corresponding A-rate coefficient. The display module is electrically connected to both the acquisition and analysis modules to display the noise data, A-rate coefficient, and real-time change curves. The PC communication module is used to communicate with a PC to transmit noise data and A-rate coefficient. The battery voltage control module provides power for the noise recording and analysis modules.

[0025] Furthermore, the noise recording and analysis module also includes a software system; the software system includes an ADC reading module, a noise amplification module, a data processing module, a data communication module, a noise display module, and a noise storage module.

[0026] Furthermore, the ADC reading module converts the noise source from analog to digital signal; the noise amplification module sets the amplification factor of the digital signal for amplification; the data processing module calculates the A-rate coefficient through the digital signal; and the data communication module is used for signal communication between the noise reduction module and the noise recording and analysis module.

[0027] Furthermore, the noise reduction module includes: a reference microphone, which receives noise sources from a specific environment and converts them into a reference signal; an error microphone, which receives noise sources inside the earcups and converts them into an error signal; an adaptive controller, which receives the reference signal, adjusts preset weight coefficients according to the A-rate coefficient to obtain a secondary signal; receives the error signal, adjusts preset weight coefficients according to the A-rate coefficient to obtain a filtered secondary signal; and repeatedly receives the error signal until the filtered secondary noise is equal in amplitude and out of phase with the noise source, thus achieving adaptive filtering and noise reduction; and a secondary microphone, which plays the secondary signal or the secondary sound source converted from the filtered secondary signal to cancel out the noise source.

[0028] Furthermore, the error microphone and the secondary microphone are horizontally spaced inside the earcup; the reference microphone is electrically connected to the external pickup, and the error microphone is electrically connected to the internal pickup.

[0029] Furthermore, the noise recording and analysis module also includes a housing cover, with a matching housing base installed at the lower end of the housing cover. A buckle is installed at the lower end of the housing base, and a power switch is provided at the upper end of the housing base. The power switch is used for the electrical connection between the noise recording and analysis module and the noise reduction module.

[0030] 3. Beneficial effects

[0031] Compared with the prior art, the advantages of this invention are:

[0032] This solution can protect people's hearing and analyze the noise they actually experience, quantifying noise exposure data and recording the frequency, level, and duration of perceived noise. This data analysis allows for evaluation of the effectiveness of protective earmuffs, providing direction for their improvement, and understanding the relative relationship between hearing and noise levels. This is of great significance for hearing protection research and has significant research and practical value. This invention is highly versatile, employing a noise analysis and recording module to analyze environmental noise and implement targeted adaptive noise reduction. This avoids the shortcomings of existing noise-canceling headphones that are not universally applicable in different environments, thus demonstrating good practicality, ease of promotion and application, and significant practical value. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the noise reduction system of the active noise reduction method of the present invention;

[0034] Figure 2 This is a schematic diagram of the active noise reduction device of the present invention;

[0035] Figure 3 This is an exploded structural diagram of the noise recording and analysis module of the present invention;

[0036] Figure 4This is a functional block diagram of the software system for the noise recording and analysis module of the present invention;

[0037] Explanation of the labels in the diagram:

[0038] 1 Error microphone, 2 Reference microphone, 3 Secondary microphone, 4 Adaptive controller, 5 Noise acquisition module, 6 Noise display module, 7 Noise storage module, 8 PC communication module, 9 Battery voltage control module, 10 Outer shell cover, 11 Outer shell base, 12 Buckle, 13 Power button. Detailed Implementation

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "top / bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0041] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "sleeved / connected," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0042] Example 1:

[0043] An adaptive noise reduction method includes the following steps:

[0044] Collect noise sources in a specific environment, convert them into noise data, and record and save the noise data;

[0045] Analyze and process noise data to determine the A-rate coefficient of noise sources in the environment;

[0046] Record and save the A-rate coefficients and send them to the adaptive controller for adaptive filtering and noise reduction;

[0047] The A-rate coefficient is determined using the following method:

[0048] In different noise environments, the noise data of the corresponding environment is processed in the frequency domain, converting the time-domain signal into a frequency-domain signal to obtain multiple frequency bands of the noise source; the sound pressure level of each frequency band is calculated, and the A-rate coefficient is used to represent the final sound pressure level of all frequency bands to display the noise data, with the unit being dBA; the formula for calculating the sound pressure level of each frequency band is as follows:

[0049]

[0050] Its A-rate coefficient formula is:

[0051]

[0052] The formula for calculating the final sound pressure level across all frequency bands is:

[0053]

[0054] In the above embodiments, sound is composed of several (or an infinite number) frequency components. Data processing is required in the frequency domain, converting the time-domain signal to a frequency-domain signal. The sound is divided into multiple frequency bands using a 1 / 3 octave band, and the sound pressure level of each octave band is calculated. To make the measured value more consistent with human subjective perception, A-rate weighting is used to represent the final sound pressure level as noise, with the unit being dBA. Finally, the noise level needs to be calibrated using a calibrator.

[0055] In the above embodiments, the adaptive controller adjusts the preset noise reduction weight coefficient according to the A-rate coefficient and performs adaptive filtering and noise reduction using an adaptive algorithm;

[0056] The adaptive algorithm uses the following formula:

[0057]

[0058] Where: x(n) is the reference signal; S(z) is the error channel; x'(n) is the filtered secondary signal; y(n) is the secondary signal; and e(n) is the error signal.

[0059] In the above embodiments, a feedforward FXLMS is employed. The system principle of feedforward FXLMS for adaptive active noise reduction control is as follows: Figure 2 As shown, it consists of an adaptive controller 4, a reference microphone 2, an error microphone 1, and a secondary sound source 3. The feedforward structure makes it easy to obtain a reference signal related to the primary noise, which helps to maintain the stability of the system.

[0060] The noise reduction methods described above can be applied to scenarios with varying levels of noise. By collecting and analyzing environmental noise, corresponding A-rate coefficients can be obtained to revise the preset weight coefficients in the adaptive noise reduction process, making the noise reduction level adapt to the noise level of the current environment, achieving targeted noise reduction, and better realizing the role of hearing protection.

[0061] Example 2:

[0062] An adaptive noise reduction device includes a pair of earmuffs, the earmuffs housing a noise recording and analysis module and a noise reduction module.

[0063] 1. The noise recording and analysis module has both hardware and software design.

[0064] Hardware design:

[0065] Includes: Acquisition module 5, Analysis module, Recording module 7, Display module 6, PC communication module 8, and Battery voltage control module 9;

[0066] The acquisition module 5 includes a built-in microphone and an external microphone. The built-in microphone is located inside the earcup to collect noise sources inside the earcup. The external microphone is located outside the earcup to collect noise sources in a specific environment. The acquisition module converts the noise sources into noise data, and uses a high-precision ADC and signal amplification circuit to amplify, condition, collect, calculate, and display the noise signal, which is then transmitted to the recording module 7, the analysis module, and the noise reduction module, respectively.

[0067] The analysis module determines the A-rate coefficient based on the noise data and sends it to the recording module 7 for A-rate coefficient under specific conditions, while simultaneously sending it to the noise reduction module. This invention uses the STM32F407VET6, a high-performance... The Cortex M4 microcontroller integrates innovative peripherals, operates at a frequency of 168MHz, and features a 32-bit flash memory MCU with a floating-point unit (FPU).

[0068] Recording module 7 records noise data and the corresponding A-rate coefficient;

[0069] Display module 6 is electrically connected to acquisition module 5 and analysis module respectively, and is used to display noise data, A-rate coefficient, and real-time change curve;

[0070] PC communication module 8 is used to communicate with the PC to transmit noise data and A-rate coefficients. It connects to the PC via a USB port and uses the FT232RL chip to communicate with the PC via a USB-to-UART serial port. This allows the PC-side software report generation software to transmit data to the PC to generate reports.

[0071] The battery voltage control module 9 is used for the power supply of the noise recording and analysis module. It has the advantages of boost / buck voltage, with an input operating voltage of DC 3-6V and an output voltage of DC 5V.

[0072] Please see Figure 3 The hardware design of the noise recording and analysis module is assembled inside a housing, which consists of a top cover 10, a base 11, and clips 12. Clips 12 are installed at the bottom of the housing. The bottom of the base 11 is fixedly connected to the battery voltage control module 9, and a power button 13 is installed at the outer end of the base 11. The power button 13 is electrically connected to the battery voltage control module 9. The upper side of the battery voltage control module 9 is electrically connected to an adaptive controller 4. The upper side of the adaptive controller 4 is electrically connected to a noise acquisition module 5 and a noise storage module 7. A noise display module 6 is installed at the top of the noise storage module 7. A PC communication module 8 is installed inside the base 11, and the PC communication module 8 is electrically connected to both the battery voltage control module 9 and the adaptive controller 4. The clips 12 facilitate the installation and removal of the module. The noise recording and analysis module is based on a modular design, which facilitates independent upgrades of the functions of each module in the future.

[0073] Software design: Please refer to Figure 4 It includes an ADC readout module, a noise amplification module, a data processing module, a data communication module, a noise display module, and a noise storage module.

[0074] The ADC readout module converts the noise signal of the analog quantity in the physical world into a digital signal that the analysis module can recognize after the ADC performs analog-to-digital conversion.

[0075] The noise amplification module is mainly used to set the amplification factor for noise acquisition, so that the data can be accurately acquired subsequently.

[0076] The data processing module performs calculations on the digital signals by weighting them using A-rate coefficients;

[0077] The data communication module is used for signal communication between the adaptive controller and the noise collection module; it is also used by the STM32F407 ARM microcontroller to perform TTL communication with the noise acquisition module, set the relevant baud rate and other parameters, send noise reading messages, and interpret the read-back messages.

[0078] 2. Please refer to Figure 2 The noise reduction module includes:

[0079] Reference microphone 2 receives noise sources from a specific environment and converts them into reference signals;

[0080] Error microphone 1 receives noise sources inside the earmuffs and converts them into error signals;

[0081] The adaptive controller 4 receives a reference signal and adjusts the preset weight coefficients according to the A-rate coefficient to obtain a secondary signal; it receives an error signal and adjusts the preset weight coefficients according to the A-rate coefficient to obtain a filtered secondary signal; it repeatedly receives the error signal until the filtered secondary noise is equal in amplitude and out of phase with the noise source, thus achieving adaptive filtering and noise reduction.

[0082] Secondary microphone 3 plays secondary signals or secondary sound sources converted from filtered secondary signals, which cancel out noise sources.

[0083] In the above embodiments, the adaptive controller 4 is electrically connected to the error microphone 1, the reference microphone 2, and the secondary microphone 3, respectively. Adaptive noise reduction is mainly performed by the adaptive controller 4, and mainly includes adaptive filtering and adaptive algorithms.

[0084] In the above embodiment, the adaptive controller 4 adjusts the preset noise reduction weight coefficients according to the A-rate coefficients, and the process of filtering and noise reduction using an adaptive algorithm is as follows: The noise signal to be eliminated in the entire specific environment has a noise source controlled by a primary loudspeaker. The reference microphone 2 receives the primary noise and sends a reference signal x(n) to the adaptive controller 4. The adaptive controller 4 calculates the secondary signal y(n) through an adaptive algorithm and sends the secondary noise. The primary noise and the secondary noise are superimposed at the error microphone 1. When the primary noise and the secondary noise are equal in amplitude and out of phase, the sound pressure is reduced after superposition, and the primary noise cancels out. When there is an error between the primary noise and the secondary noise being equal in amplitude and out of phase, an error signal e(n) is sent. The error microphone 1 receives the error signal e(n) and sends it to the adaptive controller 4. Through the correction of the A-rate coefficients of the preset weight coefficients, the amplitude and phase of the secondary signal are changed, that is, the reference signal x'(n) formed after filtering through the error channel S(z) is changed, thereby changing the secondary noise. After several calculations and adjustments of the weight coefficients, the weighted secondary noise is equal in amplitude and out of phase with the primary noise, and the system is stable.

[0085] In the above embodiment, the adaptive controller 4 communicates with the noise acquisition module 5 via the data communication module using TTL, sets the relevant baud rate and other parameters, sends a noise reading message, and interprets the read-back message.

[0086] In the above embodiment, the error microphone 1 and the secondary microphone 3 are horizontally spaced inside the earcup; the reference microphone 2 is electrically connected to the external pickup, and the error microphone 1 is electrically connected to the built-in pickup.

[0087] This invention enables hearing protection in various noise environments, analyzes the actual noise experienced by individuals, quantifies noise exposure, and records the frequency, level, and duration of perceived noise. This data analysis allows for the determination of the A-rate coefficient, enabling targeted adaptive noise reduction. It also evaluates the effectiveness of protective earmuffs, providing direction for their improvement, and reveals the relative relationship between hearing and noise levels, making it significant for hearing protection research and possessing substantial research and practical value. Furthermore, this invention is highly versatile, employing a noise analysis and recording module to analyze environmental noise and implement targeted adaptive noise reduction, avoiding the limitations of existing noise-canceling headphones that are not universally applicable in different environments. Therefore, it is highly practical, easy to promote and apply, and has significant practical value.

[0088] The above description is merely a preferred embodiment of the present invention; however, the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and its improved concepts, should be covered within the scope of protection of the present invention.

Claims

1. An adaptive noise reduction method, characterized in that: Includes the following processes: Collect noise sources in a specific environment, convert them into noise data, and record and save the noise data; The noise data is analyzed and processed to determine the A-rate coefficient of the noise source in the environment. The A-rate coefficient is recorded, saved, and sent to the adaptive controller for adaptive filtering and noise reduction. The A-rate coefficient is determined using the following method: The noise data is processed in the frequency domain to convert the time-domain signal into a frequency-domain signal, thereby obtaining multiple frequency bands of the noise source. The sound pressure level of each frequency band is calculated, and the final sound pressure level of all frequency bands is represented by the A-rate coefficient to display the noise data in dBA. The formula for calculating the sound pressure level of each frequency band is as follows: The formula for the A-rate coefficient is as follows: The formula for calculating the final sound pressure level across all frequency bands is as follows: ； The adaptive controller adjusts the preset noise reduction weight coefficients according to the A-rate coefficient and performs adaptive filtering and noise reduction using an adaptive algorithm. The adaptive controller receives a reference signal, adjusts the preset weight coefficients according to the A-rate coefficients to obtain a secondary signal, receives an error signal, adjusts the preset weight coefficients according to the A-rate coefficients to obtain a filtered secondary signal, and repeatedly receives the error signal until the filtered secondary noise is equal in amplitude and out of phase with the noise source, thereby achieving adaptive filtering and noise reduction.

2. The adaptive noise reduction method according to claim 1, characterized in that: The adaptive controller adjusts the preset noise reduction weight coefficients according to the A-rate coefficient, and performs adaptive filtering and noise reduction using an adaptive algorithm; the adaptive algorithm uses the following formula: Where: x(n) is the reference signal; S(z) is the error channel; x'(n) is the filtered secondary signal; y(n) is the secondary signal; and e(n) is the error signal.

3. An adaptive noise reduction device, characterized in that: The adaptive noise reduction method according to claim 1 or 2 includes a pair of earmuffs, wherein a noise recording and analysis module and a noise reduction module are disposed inside the earmuffs.

4. The adaptive noise reduction device according to claim 3, characterized in that: The noise recording and analysis module includes a data acquisition module, an analysis module, a recording module, a display module, a PC communication module, and a battery voltage control module. The acquisition module includes a built-in microphone and an external microphone; the built-in microphone is located inside the earcup to collect noise sources inside the earcup; the external microphone is located outside the earcup to collect noise sources in a specific environment; the acquisition module converts the noise sources into noise data and transmits them to the recording module, the analysis module, and the noise reduction module, respectively. The analysis module determines the A-rate coefficient based on the noise data and sends it to the recording module for the A-rate coefficient under a specific environment, and simultaneously sends it to the noise reduction module. The recording module records the noise data and the corresponding A-rate coefficient; The display module is electrically connected to both the acquisition module and the analysis module, and is used to display the noise data, the A-rate coefficient, and the real-time change curve. The PC communication module is used to communicate with the PC and transmit the noise data and the A-rate coefficient. The battery voltage control module is used for the power supply of the noise recording and analysis module.

5. The adaptive noise reduction device according to claim 3, characterized in that: The noise recording and analysis module also includes a software system; The software system includes an ADC reading module, a noise amplification module, a data processing module, a data communication module, a noise display module, and a noise storage module.

6. The adaptive noise reduction device according to claim 5, characterized in that: The ADC reading module converts the noise source from analog to digital signal. The noise amplification module sets the amplification factor of the digital signal for amplifying the digital signal; The data processing module calculates the A-rate coefficient using the digital signal; The data communication module is used for signal communication between the noise reduction module and the noise recording and analysis module.

7. The adaptive noise reduction device according to claim 3, characterized in that: The noise reduction module includes: A reference microphone receives the noise source in a specific environment and converts it into the reference signal; An error microphone receives the noise source inside the earcups and converts it into the error signal; An adaptive controller receives the reference signal, adjusts the preset weight coefficients according to the A-rate coefficient to obtain the secondary signal; receives the error signal, adjusts the preset weight coefficients according to the A-rate coefficient to obtain the filtered secondary signal; and repeatedly receives the error signal until the filtered secondary noise is equal in amplitude and out of phase with the noise source, thereby achieving adaptive filtering and noise reduction. The secondary microphone plays the secondary signal or the secondary sound source converted from the filtered secondary signal, which cancels out the noise source.

8. The adaptive noise reduction device according to claim 7, characterized in that: The error microphone and the secondary microphone are horizontally spaced inside the earcup; the reference microphone is electrically connected to the external pickup, and the error microphone is electrically connected to the internal pickup.

9. The adaptive noise reduction device according to claim 3, characterized in that: The noise recording and analysis module also includes an outer shell cover (1), a matching outer shell base (2) is installed at the lower end of the outer shell cover (1), a buckle (10) is installed at the lower end of the outer shell base (2), and a power switch is provided at the upper end of the outer shell base (2). The power switch is used for the electrical connection between the noise recording and analysis module and the noise reduction module.

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