CN112151002B - Noise reduction seat and noise reduction method - Google Patents
Noise reduction seat and noise reduction method Download PDFInfo
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K11/00—Methods or devices for transmitting, conducting or directing sound in general; Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/16—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general
- G10K11/175—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound
- G10K11/178—Methods or devices for protecting against, or for damping, noise or other acoustic waves in general using interference effects; Masking sound by electro-acoustically regenerating the original acoustic waves in anti-phase
- G10K11/1785—Methods, e.g. algorithms; Devices
- G10K11/17853—Methods, e.g. algorithms; Devices of the filter
- G10K11/17854—Methods, e.g. algorithms; Devices of the filter the filter being an adaptive filter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
- G10K2210/128—Vehicles
- G10K2210/1281—Aircraft, e.g. spacecraft, airplane or helicopter
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- G—PHYSICS
- G10—MUSICAL INSTRUMENTS; ACOUSTICS
- G10K—SOUND-PRODUCING DEVICES; METHODS OR DEVICES FOR PROTECTING AGAINST, OR FOR DAMPING, NOISE OR OTHER ACOUSTIC WAVES IN GENERAL; ACOUSTICS NOT OTHERWISE PROVIDED FOR
- G10K2210/00—Details of active noise control [ANC] covered by G10K11/178 but not provided for in any of its subgroups
- G10K2210/10—Applications
- G10K2210/128—Vehicles
- G10K2210/1283—Trains, trams or the like
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Abstract
The noise reduction seat comprises a headrest, a backrest, a seat part and a noise control system, and is characterized in that the noise control system comprises 2 noise signal microphones which are respectively arranged at the edge positions of the left side and the right side of the headrest and used for collecting environmental noise signals; 2m mute microphones symmetrically arranged at the left and right ear side regions of the headrest for collecting ear side noise signals; the 2 loudspeakers are respectively arranged between the noise signal microphone and the mute microphone and are used for playing anti-noise signals; the noise control system further has a controller to which the noise signal microphone, the mute microphone and the horn are connected, the controller including 4m adaptive filters for filtering and silencing a sound propagation path between the noise signal microphone and the mute microphone.
Description
Technical Field
The invention relates to the field of acoustics, in particular to an active noise control method of a vehicle.
Background
Along with the increase of the speed of the wheel track and the magnetic levitation train, the noise problem generated when the vehicle runs at high speed is also gradually highlighted. Compared with the noise of common automobile vehicles mainly from engine noise with single frequency, the noise sources of high-speed train vehicles are more complex, including noise in vehicles, noise generated by wheel-rail friction in the running process of the vehicles and noise generated by wind pressure change in the running process of the high-speed trains, the distribution range of sound components in low frequency bands is wider, and the noise components are difficult to eliminate.
At present, noise is reduced mainly through methods of enhancing train tightness, avoiding noise by adopting power original structural design, and the like, however, the train has better effect on high-frequency noise and insignificant effect on low-frequency noise due to the fact that sound can be transmitted through different media. The functional structural design is limited by the relatively large change of the components. At present, the common practice on aircrafts and trains is to distribute earplugs for each passenger, and great waste and environmental pollution are generated along with the increase of the number of riding shifts of vehicles. And as the speed of the train increases, the noise problem becomes more prominent, so that the method has great practical and economic significance for providing more comfortable riding environment for passengers.
The active noise control technology utilizes the sound wave superposition principle, referring to fig. 1, for a signal source (main wave), a noise signal (secondary wave) with the same amplitude and opposite phases is generated, and the two sound waves are mutually superposed, so that the purpose of silencing is achieved. Similar active noise reduction headphones are available in the market at present, but the active noise reduction headphones cannot be supplied in a centralized manner on large public transportation means such as trains, and passengers wearing the active noise reduction headphones for a long time or not habitually wear the active noise reduction headphones can feel uncomfortable. It is therefore desirable to mount the active noise control system on the vehicle seat, and to mount the speaker and the receiving microphone near the occupant's ears, providing the seat with active noise cancellation.
Currently, similar active noise control techniques are employed in some industries, including least mean square algorithms and filtered least mean square algorithms (FX-LMS algorithms).
An active noise control system adopting a least mean square algorithm constructs an adaptive filter based on the least mean square algorithm to control noise reduction, the least mean square algorithm can track changed input signals, set parameters of the adaptive filter can be automatically adjusted according to the input parameters, and continuous modeling is carried out to simulate a sound channel, the active noise control system adopting the least mean square algorithm is structurally shown in fig. 2, a noise signal source x (n) penetrates through an unknown channel P (z) to form main source noise d (n), an output y (n) of a digital adaptive filter W (z) is adjusted according to the input signal x (n) and an error signal e (n) captured by an error sensor, and the input signal x (n) and the error signal e (n) serve as feedback signals to adjust parameters W (z) of the digital adaptive filter. The active noise control system brings the error signal e (n) to a minimum mean square value by continuously adjusting the digital adaptive filter parameter W (z).
The input signal x (N) is formed by a set of vectors x (N) = [ x (N), x (N-1), …, x (N-n+1)]T represents the output signal y (n) by the formulaThe error signal e (n) is calculated from the formula e (n) =d (n) -y (n). Minimum mean square error E [ E ] 2 (n)]From the least mean square value formula E [ E ] 2 (n)]＝E[d 2 (n)]-2P T w(n)+w T (n) Rw (n) where P=Ed (n) x (n)]Is the cross-correlation vector of the desired signal and the input signal, r=e [ x (n) x ] T (n)]Is the autocorrelation matrix of the input signal, and the vector of w (n) is the adaptive filter coefficient and the mean square error E [ E ] 2 (n)]In relation, it is calculated from the equation w (n+1) =w (n) +μe (n) x (n). The least mean square algorithm has a low computational complexity to update the adaptive filter coefficients, nor takes into account the actual signal variations of the adaptive filter from the output to the error acquisition point.
The FX-LMS algorithm is an algorithm that adds compensation based on the least mean square algorithm, see fig. 3, where the error signal e (n) is represented by the formula e (n) =d (n) -s (n) ×w T (n)x(n)]The adaptive filter coefficient w (n) is calculated from w (n+1) =w (n) +μe (n) x '(n), where x' (n) =x (n) s (n), where s (n) is the acoustic channel transfer function, and is measured in advance before addition to the calculation. Current single channel active noise control techniques can eliminate noise in a wider frequency band, but the quiet area to eliminate noise is very small and does not provide adequate comfort to the user.
Disclosure of Invention
The invention aims to solve the technical problems of providing an active noise control technology for vehicles such as magnetic suspension and the like aiming at the defects of the prior art, optimizes the arrangement positions of a microphone and a loudspeaker by adopting the multichannel active noise control technology, improves a noise control algorithm and solves the problem of too small noise reduction area.
In order to solve the above problems, according to a first aspect of the present invention, there is provided a noise reduction seat including a headrest, a backrest, a seat portion, and a noise control system including:
the 2 noise signal microphones comprise a 1 st noise signal microphone and a 2 nd noise signal microphone which are respectively arranged at the edge positions of the left side and the right side of the headrest and are used for collecting environmental noise signals;
the 2m mute microphones are more than or equal to 1, comprise a 1 st mute microphone, a 2 nd mute microphone, a … … and a 2 nd mute microphone, are symmetrically arranged at the left and right ear side region positions of a passenger of the headrest and are used for collecting ear side noise signals;
the 2 loudspeakers comprise a 1 st loudspeaker and a 2 nd loudspeaker, are respectively arranged between the noise signal microphone and the mute microphone and are used for playing anti-noise signals;
the noise control system is further provided with a controller, the 1 st noise signal microphone, the 2 nd noise signal microphone, the 1 st mute microphone, the 2 nd mute microphone, … …, the 2 nd mute microphone, the 1 st loudspeaker and the 2 nd loudspeaker are connected with the controller, and the controller comprises 4m adaptive filters in total, namely a 1 st adaptive filter, a 2 nd adaptive filter, … … and a 4 th adaptive filter, and is used for filtering and silencing a sound propagation path between the noise signal microphone and the mute microphone.
Preferably, the noise control system adopts an FX-LMS algorithm to perform active noise reduction control, and the method comprises the following steps:
step 1: the 1 st noise signal microphone collects noise signals and generates noise source signals x1 (n) after synthesis processing to serve as input signals of the 1 st to 2 nd m adaptive filters, and the 2 nd noise signal microphone collects noise signals and generates noise source signals x2 (n) serving as input signals of the 2m+1 st to 4 th m adaptive filters after synthesis processing;
step 2: the 4m adaptive filters respectively output anti-noise signals y1 (n), y2 (n), … … and y4m (n) according to the input signals;
step 3: the 1 st loudspeaker and the 2 nd loudspeaker play the anti-noise signals y1 (n), y2 (n), … … and y4m (n) at the same time;
step 4: the 1 st mute microphone collects a near-ear noise signal e1 (n), the 2 nd mute microphone collects a near-ear noise signal e2 (n), … …, the 2 nd mute microphone collects a near-ear noise signal e2m (n), the near-ear noise signal e1 (n) is an error between the anti-noise signals y1 (n) and y2m+1 (n) and the noise source signals x1 (n) and x2 (n), the near-ear noise signal e2 (n) is an error between the anti-noise signals y2 (n) and y2m+2 (n) and the noise source signals x1 (n) and x2 (n), … …, and the near-ear noise signal e2m (n) is an error between the anti-noise signals y2m (n) and y4m (n) and the noise source signals x1 (n) and x2 (n);
step 5: the 1 st to 2 nd m adaptive filters respectively adjust output anti-noise signals y1 (n), y2 (n), … …, y2m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x1 (n), and the 2m+1 th to 4 th m adaptive filters respectively adjust output anti-noise signals y2m+l (n), y2m+2 (n), … …, y4m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
Preferably, the step 4 further includes:
step 41: the noise source signals x1 (n) respectively generate main source noises d11 (n), d12 (n), … … and d1 (2 m) (n) through air paths P1 (z), P2 (z), … … and P2m (z), and the noise source signals x2 (n) respectively generate main source noises d21 (n), d22 (n), … … and d2 (2 m) (n) through air paths P2m+1 (z), P2m+2 (z), … … and P4m (z);
step 42: the anti-noise signal y1 (n) generates a corrected anti-noise signal y11 (n) and y12 (n) through the sound channel transfer functions S11 (z) and S21 (z), the anti-noise signal y2 (n) generates a corrected anti-noise signal y21 (n) and y22 (n) through the sound channel transfer functions S12 (z) and S22 (z), … …, the anti-noise signal y2m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) 2 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2m+1 (n) generates a corrected anti-noise signal y (2m+1) 1 (n) and y (2m+1) 2 (n), … …, respectively, and the anti-noise signal y4m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) through the sound channel transfer functions S12m (z) and S22m (z), respectively;
step 43: the 1 st mute microphone collects differences between the corrected anti-noise signals y11 (n), y12 (n), y (2m+1) 1 (n) and y (2m+1) 2 (n) and the main source noise d11 (n), d21 (n), i.e., the ear side noise signal e1 (n), the 2 nd mute microphone collects differences between the corrected anti-noise signals y21 (n), y22 (n), y (2m+2) 1 (n) and y (2m+2) 2 (n) and the main source noise d12 (n), d22 (n), i.e., the ear side noise signals e2 (n), … …, and the 2 nd mute microphone collects differences between the corrected anti-noise signals y (2 m) 1 (n), y (2 m) 2 (n), y (4 m) 1 (n) and y (4 m) 2 (n) and the main source noise d1 (2 m) (n), i.e., the ear side noise signal e (n).
According to a second aspect of the present invention, there is provided a noise reduction method for the noise reduction seat described above, the method employing an FX-LMS algorithm, comprising the steps of:
step 1: the 1 st noise signal microphone collects noise signals and a noise source signal x1 (n) generated after synthesis processing is input into the 1 st to 2 nd m adaptive filters and the 1 st to 2 nd adaptive filters, and the 2 nd noise signal microphone collects noise signals and a noise source signal x2 (n) generated after synthesis processing is input into the 2m+1 th to 4 th adaptive filters, wherein m is more than or equal to 1;
step 2: the 1 st to 4 th m adaptive filters output anti-noise signals y1 (n), y2 (n), … …, y4m (n) according to the input signals, respectively;
step 3: the 1 st loudspeaker and the 2 nd loudspeaker play the anti-noise signals y1 (n), y2 (n), … … and y4m (n) at the same time;
step 4: the 1 st mute microphone collects a near-ear noise signal e1 (n), the 2 nd mute microphone collects a near-ear noise signal e2 (n), … …, the 2 nd mute microphone collects a near-ear noise signal e2m (n), the near-ear noise signal e1 (n) is an error between the anti-noise signals y1 (n) and y2m+1 (n) and the noise source signals x1 (n) and x2 (n), the near-ear noise signal e2 (n) is an error between the anti-noise signals y2 (n) and y2m+2 (n) and the noise source signals x1 (n) and x2 (n), … …, and the near-ear noise signal e2m (n) is an error between the anti-noise signals y2m (n) and y4m (n) and the noise source signals x1 (n) and x2 (n);
step 5: the 1 st to 2 nd m adaptive filters respectively adjust output anti-noise signals y1 (n), y2 (n), … …, y2m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x1 (n), and the 2m+1 th to 4 th m adaptive filters respectively adjust output anti-noise signals y2m+l (n), y2m+2 (n), … …, y4m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
Preferably, the step 4 further includes:
step 41: the noise source signals x1 (n) respectively generate main source noises d11 (n), d12 (n), … … and d1 (2 m) (n) through air paths P1 (z), P2 (z), … … and P2m (z), and the noise source signals x2 (n) respectively generate main source noises d21 (n), d22 (n), … … and d2 (2 m) (n) through air paths P2m+1 (z), P2m+2 (z), … … and P4m (z);
step 42: the anti-noise signal y1 (n) generates a corrected anti-noise signal y11 (n) and y12 (n) through the sound channel transfer functions S11 (z) and S21 (z), the anti-noise signal y2 (n) generates a corrected anti-noise signal y21 (n) and y22 (n) through the sound channel transfer functions S12 (z) and S22 (z), … …, the anti-noise signal y2m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) 2 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2m+1 (n) generates a corrected anti-noise signal y (2m+1) 1 (n) and y (2m+1) 2 (n), … …, respectively, and the anti-noise signal y4m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) through the sound channel transfer functions S12m (z) and S22m (z), respectively;
step 43: the 1 st mute microphone collects differences between the corrected anti-noise signals y11 (n), y12 (n), y (2m+1) 1 (n) and y (2m+1) 2 (n) and the main source noise d11 (n), d21 (n), i.e., the ear side noise signal e1 (n), the 2 nd mute microphone collects differences between the corrected anti-noise signals y21 (n), y22 (n), y (2m+2) 1 (n) and y (2m+2) 2 (n) and the main source noise d12 (n), d22 (n), i.e., the ear side noise signals e2 (n), … …, and the 2 nd mute microphone collects differences between the corrected anti-noise signals y (2 m) 1 (n), y (2 m) 2 (n), y (4 m) 1 (n) and y (4 m) 2 (n) and the main source noise d1 (2 m) (n), i.e., the ear side noise signal e (n).
Compared with the prior art, the method has the advantages of more accurate algorithm parameters, more accurate calculated anti-noise signals, improved noise reduction effect, more possibility for system optimization, low cost, small occupied area and low-frequency noise removal, provides a vehicle noise solution for a high-speed train or an airplane, and improves the comfort of passengers taking the train. The invention adopts a multichannel active noise control technology, optimizes the arrangement positions of a microphone and a loudspeaker, adds a feedforward noise elimination system and preprocesses the input noise signals, accurately measures the parameter information of a sound transmission path, adjusts a self-adaptive filter to find a proper algorithm iteration step value, improves the accuracy of anti-noise signals and improves the noise reduction effect.
Drawings
The foregoing summary of the invention, as well as the following detailed description of the invention, will be better understood when read in conjunction with the accompanying drawings. It is to be noted that the drawings are merely examples of the claimed invention. In the drawings, like reference numbers indicate identical or similar elements.
FIG. 1 is a schematic diagram of an active noise control principle;
FIG. 2 is a schematic diagram of a noise control system employing a least mean square algorithm;
FIG. 3 is a schematic diagram of a noise control system architecture employing the FxLMS algorithm;
FIG. 4 is a schematic view of a noise reduction seat according to an embodiment of the invention;
fig. 5 is a schematic diagram of a noise control system according to an embodiment of the invention.
FIG. 6 is an active noise reduction control flow in accordance with an embodiment of the present invention; and
fig. 7 is a process flow of the near-ear noise signal acquisition according to an embodiment of the invention.
Detailed Description
The detailed features and advantages of the present invention will be readily apparent to those skilled in the art from the following detailed description, claims, and drawings that follow.
As a first aspect of the present invention, a noise reduction seat is provided that can be used in medium and high speed vehicles. As shown in fig. 4, the noise reducing seat according to the present invention includes a headrest, a backrest, a seat portion, and a noise control system including an active noise control system of a plurality of individual channels. The noise control system includes:
the 1 st noise signal microphone and the 2 nd noise signal microphone are respectively arranged at the edge positions of the left side and the right side of the headrest and are used for collecting environmental noise signals;
the 1 st mute microphone and the 2 nd mute microphone are respectively arranged at the left and right ear side region positions of the passengers of the headrest and are used for collecting ear side noise signals;
the 1 st loudspeaker and the 2 nd loudspeaker are respectively arranged between the noise signal microphone and the mute microphone and are used for playing anti-noise signals;
the noise control system further has a controller, the 1 st noise signal microphone, the 2 nd noise signal microphone, the 1 st mute microphone, the 2 nd mute microphone, the 1 st speaker and the 2 nd speaker are connected with the controller, the controller includes a 1 st adaptive filter W1 (z), a 2 nd adaptive filter W2 (z), a 3 rd adaptive filter W3 (z), a 4 th adaptive filter W4 (z), wherein the 1 st adaptive filter to the 4 th adaptive filter are capable of filtering and silencing four sound propagation paths between two noise sources (the 1 st and 2 nd noise signal microphones) to the two mute microphones, respectively.
It should be noted that the present invention is not limited to two mute microphones, four mute microphones may be provided to expand the noise reduction area and improve the noise reduction effect, correspondingly, the number of adaptive filters in the noise control system increases to eight, the number of sound propagation paths needing to be filtered and silenced also increases to eight, if the noise reduction effect needs to be further enhanced, the mute microphones may be expanded to 2m, and the number of corresponding adaptive filters and the number of sound propagation paths needing to be filtered and silenced may be expanded to 4 m.
Further, according to another aspect of the present invention, the noise control system performs a noise reduction method, and performs active noise reduction control using FX-LMS algorithm, referring to fig. 5 and 6, in case that the noise control system of the present invention includes only two mute microphones, the noise control system includes the following steps:
step 1: the 1 st noise signal microphone collects noise signals and generates noise source signals x1 (n) after synthesis processing to serve as input signals of the 1 st adaptive filter and the 2 nd adaptive filter, and the 2 nd noise signal microphone collects noise signals and generates noise source signals x2 (n) after synthesis processing to serve as input signals of the 3 rd adaptive filter and the 4 th adaptive filter;
step 2: the 1 st adaptive filter and the 3 rd adaptive filter respectively output anti-noise signals y1 (n) and y3 (n) according to input signals, and the 2 nd adaptive filter and the 4 th adaptive filter respectively output anti-noise signals y2 (n) and y4 (n) according to the input signals;
step 3: the 1 st horn and the 2 nd horn play anti-noise signals y1 (n), y2 (n), y3 (n) and y4 (n) at the same time;
step 4: the 1 st mute microphone collects the ear-side noise signal e1 (n), the 2 nd mute microphone collects the ear-side noise signal e2 (n), the ear-side noise signal e1 (n) is the error of the anti-noise signals y1 (n) and y3 (n) and the noise source signals x1 (n) and x2 (n), and the ear-side noise signal e2 (n) is the error of the anti-noise signals y2 (n) and y4 (n) and the noise source signals x1 (n) and x2 (n);
step 5: the 1 st adaptive filter and the 2 nd adaptive filter respectively adjust output anti-noise signals y1 (n) and y2 (n) according to the ear side noise signals e1 (n) and e2 (n) and the noise source signal x1 (n), and the 3 rd adaptive filter and the 4 th adaptive filter respectively adjust output anti-noise signals y3 (n) and y4 (n) according to the ear side noise signals e1 (n) and e2 (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
Further, referring to fig. 7, the step 4 further includes:
step 41: the noise source signals x1 (n) generate main source noises d11 (n) and d12 (n) through air paths P1 (z) and P2 (z), respectively, the noise source signals x2 (n) generate main source noises d21 (n) and d22 (n) through air paths P3 (z) and P4 (z), respectively, and the P1 (z), the P2 (z), the P3 (z) and the P4 (z) are 4 air path channels from the 1 st and the 2 nd noise collecting microphones to the 1 st and the 2 nd mute microphones beside the ear;
step 42: the anti-noise signal y1 (n) generates modified anti-noise signals y11 (n) and y12 (n) via sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2 (n) generates modified anti-noise signals y21 (n) and y22 (n) via sound channel transfer functions S12 (z) and S22 (z), respectively, the anti-noise signal y3 (n) generates modified anti-noise signals y31 (n) and y32 (n) via sound channel transfer functions S11 (z) and S21 (z), respectively, and the anti-noise signal y4 (n) generates modified anti-noise signals y41 (n) and y42 (n) via sound channel transfer functions S12 (z) and S22 (z), respectively, wherein the sound channel transfer functions are analog paths of the air path;
step 43: the 1 st mute microphone collects the differences between the corrected anti-noise signals y11 (n), y12 (n), y31 (n) and y32 (n) and the main source noises d11 (n), d21 (n), i.e. the near-ear noise signal e1 (n), and the 2 nd mute microphone collects the differences between the corrected anti-noise signals y21 (n), y22 (n), y41 (n) and y42 (n) and the main source noises d12 (n), d22 (n), i.e. the near-ear noise signal e2 (n).
Similarly, if the number of mute microphones in the noise control system is increased to 2m, where m is greater than or equal to 1, the noise reduction method includes the following steps:
step 1: the 1 st noise signal microphone collects noise signals and generates noise source signals x1 (n) after synthesis processing as input signals of the 1 st to 2 nd m adaptive filters, and the 2 nd noise signal microphone collects noise signals and generates noise source signals x2 (n) as input signals of the 2m+1 th to 4 th m adaptive filters after synthesis processing;
step 2: the 4m adaptive filters respectively output anti-noise signals y1 (n), y2 (n), … … and y4m (n) according to the input signals;
step 3: the 1 st loudspeaker and the 2 nd loudspeaker play anti-noise signals y1 (n), y2 (n), … … and y4m (n) at the same time;
step 4: the 1 st mute microphone collects the ear side noise signal e1 (n), the 2 nd mute microphone collects the ear side noise signal e2 (n), … …, the 2 nd mute microphone collects the ear side noise signal e2m (n), the ear side noise signal e1 (n) is the error of the anti-noise signals y1 (n) and y2m+1 (n) and the noise source signals x1 (n) and x2 (n), the ear side noise signal e2 (n) is the error of the anti-noise signals y2 (n) and y2m+2 (n) and the noise source signals x1 (n) and x2 (n), … …, the ear side noise signal e2m (n) is the error of the anti-noise signals y2m (n) and y4m (n) and the noise source signals x1 (n) and x2 (n);
step 5: the 1 st to 2 nd adaptive filters respectively adjust the output anti-noise signals y1 (n), y2 (n), … …, y2m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x1 (n), and the 2m+1 st to 4 th adaptive filters respectively adjust the output anti-noise signals y2m+l (n), y2m+2 (n), … …, y4m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
The step 4 further includes:
step 41: noise source signals x1 (n) generate main source noise d11 (n), d12 (n), … …, d1 (2 m) (n) through air paths P1 (z), P2 (z), … …, P2m (z), respectively, noise source signals x2 (n) generate main source noise d21 (n), d22 (n), … …, d2 (2 m) (n) through air paths p2m+1 (z), p2m+2 (z), … …, P4m (z), respectively, P1 (z), P2 (z), … …, P4m (z) are 4m air path channels from the 1 st and 2 nd noise collecting microphones to the 2m mute microphones near the ear;
step 42: the anti-noise signal y1 (n) generates modified anti-noise signals y11 (n) and y12 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2 (n) generates modified anti-noise signals y21 (n) and y22 (n) through the sound channel transfer functions S12 (z) and S22 (z), respectively, … …, the anti-noise signal y2m (n) generates modified anti-noise signals y (2 m) 1 (n) and y (2 m) 2 (n) through the sound channel transfer functions S12m (z) and S22m (z), respectively, the anti-noise signal y2m+1 (n) generates modified anti-noise signals y (2m+1) 1 (n) and y (2 m+1) 2 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, … …, and the anti-noise signal y4m (n) generates modified anti-noise signals y (2 m) 1 (n) and y (4 m) 2 (n) through the sound channel transfer functions S12m (z) and S22m (z), respectively;
step 43: the 1 st mute microphone collects differences between correction positive noise signals y11 (n), y12 (n), y (2m+1) 1 (n) and y (2m+1) 2 (n) and main source noise d11 (n), d21 (n), that is, ear side noise signals e1 (n), the 2 nd mute microphone collects differences between correction positive noise signals y21 (n), y22 (n), y (2m+2) 1 (n) and y (2m+2) 2 (n) and main source noise d12 (n), d22 (n), that is, ear side noise signals e2 (n), … …, the 2 nd mute microphone collects differences between correction positive noise signals y (2 m) 1 (n), y (2 m) 2 (n), y (4 m) 1 (n) and y (4 m) 2 (n) and main source noise d1 (2 m) (n), d 2m (n), that is, ear side noise signals e2m (n).
The terms and expressions which have been employed herein are used as terms of description and not of limitation. The use of these terms and expressions is not meant to exclude any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible and are intended to be included within the scope of the claims. Other modifications, variations, and alternatives, such as replacement of components of different specifications, are also possible. Accordingly, the claims should be looked to in order to cover all such equivalents.
Also, it should be noted that while the present invention has been described with reference to the particular embodiments presently, it will be appreciated by those skilled in the art that the above embodiments are provided for illustration only and that various equivalent changes or substitutions may be made without departing from the spirit of the invention, and therefore, the changes and modifications to the above embodiments shall fall within the scope of the claims of the present application as long as they are within the true spirit of the invention.
Claims (4)
1. A noise reduction seat comprising a headrest, a backrest, a seat portion, and a noise control system, the noise control system comprising:
the 2 noise signal microphones comprise a 1 st noise signal microphone and a 2 nd noise signal microphone which are respectively arranged at the edge positions of the left side and the right side of the headrest and are used for collecting environmental noise signals;
the 2m mute microphones are more than or equal to 1, comprise a 1 st mute microphone, a 2 nd mute microphone, a … … and a 2 nd mute microphone, are symmetrically arranged at the left and right ear side region positions of a passenger of the headrest and are used for collecting ear side noise signals;
the 2 loudspeakers comprise a 1 st loudspeaker and a 2 nd loudspeaker, are respectively arranged between the noise signal microphone and the mute microphone and are used for playing anti-noise signals;
the noise control system is further provided with a controller, wherein the 1 st noise signal microphone, the 2 nd noise signal microphone, the 1 st mute microphone, the 2 nd mute microphone, … …, the 2 nd mute microphone, the 1 st loudspeaker and the 2 nd loudspeaker are connected with the controller, and the controller comprises a 1 st adaptive filter, a 2 nd adaptive filter, … … and a 4 th m adaptive filter, and the 4m adaptive filters are used for respectively filtering and silencing sound propagation paths from each noise signal microphone to each mute microphone;
the noise control system adopts a filtering least mean square algorithm to perform active noise reduction control, and the following steps are executed:
step 1: the 1 st noise signal microphone collects noise signals and generates noise source signals x1 (n) after synthesis processing to serve as input signals of the 1 st to 2 nd m adaptive filters, and the 2 nd noise signal microphone collects noise signals and generates noise source signals x2 (n) after synthesis processing to serve as input signals of the 2m+1 st to 4 th m adaptive filters;
step 2: the 4m adaptive filters respectively output anti-noise signals y1 (n), y2 (n), … … and y4m (n) according to the input signals;
step 3: the 1 st loudspeaker and the 2 nd loudspeaker play the anti-noise signals y1 (n), y2 (n), … … and y4m (n) at the same time;
step 4: the 1 st mute microphone collects a near-ear noise signal e1 (n), the 2 nd mute microphone collects a near-ear noise signal e2 (n), … …, the 2 nd mute microphone collects a near-ear noise signal e2m (n), the near-ear noise signal e1 (n) is an error between the anti-noise signals y1 (n) and y2m+1 (n) and the noise source signals x1 (n) and x2 (n), the near-ear noise signal e2 (n) is an error between the anti-noise signals y2 (n) and y2m+2 (n) and the noise source signals x1 (n) and x2 (n), … …, and the near-ear noise signal e2m (n) is an error between the anti-noise signals y2m (n) and y4m (n) and the noise source signals x1 (n) and x2 (n);
the step 4 further comprises:
step 41: the noise source signals x1 (n) respectively generate main source noises d11 (n), d12 (n), … … and d1 (2 m) (n) through air paths P1 (z), P2 (z), … … and P2m (z), and the noise source signals x2 (n) respectively generate main source noises d21 (n), d22 (n), … … and d2 (2 m) (n) through air paths P2m+1 (z), P2m+2 (z), … … and P4m (z);
step 42: the anti-noise signal y1 (n) generates a corrected anti-noise signal y11 (n) and y12 (n) through the sound channel transfer functions S11 (z) and S21 (z), the anti-noise signal y2 (n) generates a corrected anti-noise signal y21 (n) and y22 (n) through the sound channel transfer functions S12 (z) and S22 (z), … …, the anti-noise signal y2m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) 2 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2m+1 (n) generates a corrected anti-noise signal y (2m+1) 1 (n) and y (2m+1) 2 (n), … …, respectively, and the anti-noise signal y4m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) through the sound channel transfer functions S12m (z) and S22m (z), respectively;
step 43: the 1 st mute microphone collects differences between the corrected anti-noise signals y11 (n), y12 (n), y (2m+1) 1 (n) and y (2m+1) 2 (n) and the main source noise d11 (n), d21 (n), i.e., the ear side noise signal e1 (n), the 2 nd mute microphone collects differences between the corrected anti-noise signals y21 (n), y22 (n), y (2m+2) 1 (n) and y (2m+2) 2 (n) and the main source noise d12 (n), d22 (n), i.e., the ear side noise signals e2 (n), … …, and the 2 nd mute microphone collects differences between the corrected anti-noise signals y (2 m) 1 (n), y (2 m) 2 (n), y (4 m) 1 (n) and y (4 m) 2 (n) and the main source noise d1 (2 m) (n), i.e., the ear side noise signal e (n).
2. The noise reducing seat of claim 1, wherein the noise control system further performs the following steps after performing step 4:
step 5: the 1 st to 2 nd m adaptive filters respectively adjust output anti-noise signals y1 (n), y2 (n), … …, y2m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x1 (n), and the 2m+1 th to 4 th m adaptive filters respectively adjust output anti-noise signals y2m+l (n), y2m+2 (n), … …, y4m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
3. A method of noise reduction for a noise reduction seat as defined in claim 1, said method employing a filtered least mean square algorithm comprising the steps of:
step 1: the 1 st noise signal microphone collects noise signals and generates noise source signals x1 (n) after synthesis processing, the noise source signals x1 (n) are input into the 1 st to 2 nd m adaptive filters, and the 2 nd noise signal microphone collects noise signals and generates noise source signals x2 (n) after synthesis processing, the noise source signals x2 (n) are input into the 2 nd+1 st to 4 th m adaptive filters, wherein m is more than or equal to 1;
step 2: the 1 st to 4 th m adaptive filters output anti-noise signals y1 (n), y2 (n), … …, y4m (n) according to the input signals, respectively;
step 3: the 1 st loudspeaker and the 2 nd loudspeaker play the anti-noise signals y1 (n), y2 (n), … … and y4m (n) at the same time;
step 4: the 1 st mute microphone collects a near-ear noise signal e1 (n), the 2 nd mute microphone collects a near-ear noise signal e2 (n), … …, the 2 nd mute microphone collects a near-ear noise signal e2m (n), the near-ear noise signal e1 (n) is an error between the anti-noise signals y1 (n) and y2m+1 (n) and the noise source signals x1 (n) and x2 (n), the near-ear noise signal e2 (n) is an error between the anti-noise signals y2 (n) and y2m+2 (n) and the noise source signals x1 (n) and x2 (n), … …, and the near-ear noise signal e2m (n) is an error between the anti-noise signals y2m (n) and y4m (n) and the noise source signals x1 (n) and x2 (n);
step 5: the 1 st to 2 nd m adaptive filters respectively adjust output anti-noise signals y1 (n), y2 (n), … …, y2m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x1 (n), and the 2m+1 th to 4 th m adaptive filters respectively adjust output anti-noise signals y2m+l (n), y2m+2 (n), … …, y4m (n) according to the ear-side noise signals e1 (n), e2 (n), … …, e2m (n) and the noise source signal x2 (n);
step 6: repeating the steps 3 to 5.
4. The noise reduction method according to claim 3, wherein the step 4 further comprises:
step 41: the noise source signals x1 (n) respectively generate main source noises d11 (n), d12 (n), … … and d1 (2 m) (n) through air paths P1 (z), P2 (z), … … and P2m (z), and the noise source signals x2 (n) respectively generate main source noises d21 (n), d22 (n), … … and d2 (2 m) (n) through air paths P2m+1 (z), P2m+2 (z), … … and P4m (z);
step 42: the anti-noise signal y1 (n) generates a corrected anti-noise signal y11 (n) and y12 (n) through the sound channel transfer functions S11 (z) and S21 (z), the anti-noise signal y2 (n) generates a corrected anti-noise signal y21 (n) and y22 (n) through the sound channel transfer functions S12 (z) and S22 (z), … …, the anti-noise signal y2m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) 2 (n) through the sound channel transfer functions S11 (z) and S21 (z), respectively, the anti-noise signal y2m+1 (n) generates a corrected anti-noise signal y (2m+1) 1 (n) and y (2m+1) 2 (n), … …, respectively, and the anti-noise signal y4m (n) generates a corrected anti-noise signal y (2 m) 1 (n) and y (2 m) through the sound channel transfer functions S12m (z) and S22m (z), respectively;
step 43: the 1 st mute microphone collects differences between the corrected anti-noise signals y11 (n), y12 (n), y (2m+1) 1 (n) and y (2m+1) 2 (n) and the main source noise d11 (n), d21 (n), i.e., the ear side noise signal e1 (n), the 2 nd mute microphone collects differences between the corrected anti-noise signals y21 (n), y22 (n), y (2m+2) 1 (n) and y (2m+2) 2 (n) and the main source noise d12 (n), d22 (n), i.e., the ear side noise signals e2 (n), … …, and the 2 nd mute microphone collects differences between the corrected anti-noise signals y (2 m) 1 (n), y (2 m) 2 (n), y (4 m) 1 (n) and y (4 m) 2 (n) and the main source noise d1 (2 m) (n), i.e., the ear side noise signal e (n).
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