CN114155827A - Feedback type active anti-noise system for controlling bi-level and bi-level error amount - Google Patents
Feedback type active anti-noise system for controlling bi-level and bi-level error amount 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
- G10K11/1781—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions
- G10K11/17821—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 characterised by the analysis of input or output signals, e.g. frequency range, modes, transfer functions characterised by the analysis of the input signals only
- G10K11/17825—Error signals
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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
- 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
- G10K11/1787—General system configurations
- G10K11/17875—General system configurations using an error signal without a reference signal, e.g. pure feedback
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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
- G10K2210/30—Means
- G10K2210/301—Computational
- G10K2210/3026—Feedback
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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
- G10K2210/30—Means
- G10K2210/301—Computational
- G10K2210/3028—Filtering, e.g. Kalman filters or special analogue or digital filters
Abstract
A feedback active anti-noise system for bi-level and bi-level error control includes an error receiver, an audio output device, an error shaper and a feedback module. The error receiving device receives the error sound source signal and outputs an error signal. The audio output device outputs an audio signal. The input end of the error shaper is connected to the error receiving device to receive the error signal, and the error shaper eliminates the high-frequency noise of the error signal and outputs an error shaping signal. The input end of the feedback module is connected to the output end of the error shaper and receives the audio signal, and the feedback module outputs a noise reduction signal according to the error shaping signal and the audio signal.
Description
Technical Field
The application belongs to the technical field of feedback type active noise resistance, and particularly relates to a feedback type active noise resistance system for controlling bi-level and bi-level error volume.
Background
Active Noise Control (ANC) is a device that can block off specified Noise, while leaving other sounds unaffected. The main principle is that the sound source receiving device receives specified noise, and the sound transmitting device sends out sound waves with completely opposite phases, so that the two sound waves can be mutually cancelled, and the noise is filtered. The active anti-noise technology is widely applied to sound insulation horns and noise reduction earphones of airplanes and warplanes at present.
The conventional feedback active anti-noise technique mainly converts the received error signal into a corresponding reverse signal through a filter (FIR filter), thereby filtering the noise. However, the high frequency of the input error signal may cause the adaptive operation at the front end of the filter (FIR filter) to diverge, resulting in poor noise reduction.
Disclosure of Invention
The embodiment of the application provides a feedback type active anti-noise system for controlling a biquadratic error rate, which can improve the noise reduction effect.
In a first aspect, an embodiment of the present application provides a feedback active anti-noise system for biquad error rate control, including: an error receiving device, an audio output device, an error shaper and a feedback module. The error receiving device receives the error audio signal and outputs an error signal. The audio output device outputs an audio signal. The input end of the error shaper is connected to the error receiving device to receive the error signal, the error shaper comprises a noise bandwidth detector, a coefficient corrector of which the input end is connected to the noise bandwidth detector and a 1-N order biquad filter of which the input end is connected to the coefficient corrector, the noise bandwidth detector calculates the bandwidth of the error signal, the coefficient corrector corrects the coefficient of the 1-N order biquad filter according to the bandwidth of the error signal, and the 1-N order biquad filter eliminates the high-frequency noise of the error signal of the next sampling according to the corrected coefficient and outputs an error shaping signal. The input terminal of the feedback module is connected to the output terminal of the error shaper and receives the audio signal, the output end of the feedback module is connected to the audio output device, the feedback module comprises a mixer, an LMS operator whose input end is connected with the output end of the error shaper and the output end of the mixer, and an adaptive filter whose input end is connected with the output end of the LMS operator and the output end of the mixer, the input end of the mixer is connected to the output end of the error shaper and receives the audio signal, the mixer mixes the error shaped signal and the audio signal and outputs a mixed signal, the LMS operator updates the weight coefficient of the adaptive filter according to the received error-shaped signal and the mixed signal, the adaptive filter filters the mixed signal according to the updated weight coefficient and outputs a noise reduction signal to the audio output device.
Therefore, compared with the prior art, the method and the device can reduce the high-frequency noise of the error signal, and can further avoid the reduction of the noise reduction effect caused by the operation divergence of the adaptive filter besides adjusting the eliminated high-frequency noise according to the requirement.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive exercise.
FIG. 1 is a block diagram of a bi-quad error control feedback active anti-noise system according to an embodiment of the present application;
FIG. 2 is a block diagram of an error shaper according to an embodiment of the present disclosure;
FIG. 3 is a block diagram of a biquad filter according to another embodiment of the present application;
FIG. 4 is a block diagram illustrating a hierarchical arrangement of a 1-Nth order biquad filter according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of the control logic of a bi-quad error control feedback active anti-noise system according to an embodiment of the present application;
fig. 6 is a schematic flow chart of a feedback active anti-noise system with bi-level error control according to an embodiment of the present application.
Wherein, in the drawings, the reference numerals are mainly as follows:
a feedback active anti-noise system for 100 biquadratic error control; 10 error receiving means;
12 error microphones; 14 a preamplifier; 16 an anti-aliasing filter; 18 analog-to-digital converter;
20 an audio output device; 22 a digital-to-analog converter; 24 a reconstruction filter; 26 a power amplifier;
28 a speaker; 30 error shapers; a 32 noise bandwidth detector; a 34 coefficient corrector;
361 to Nth order biquad filters; 361-36N biquad filter; 40 a feedback module;
41 a first secondary path filter; 42 a mixer; 43 a second secondary path filter;
44 LMS arithmetic unit; 46 an adaptive filter; NS noise.
Detailed Description
The detailed description and technical contents of the present application will be described below with reference to the accompanying drawings. In addition, for convenience of description, the drawings and the proportion thereof are not necessarily drawn to scale, and the drawings and the proportion thereof are not intended to limit the scope of the present application, which is described herein.
The embodiments of the present application can be implemented in a noise reduction device or a noise reduction controller in a personal listening system including a wired headset, a smart phone handset, a wireless headset or other head-worn audio device, which is not limited in the present application.
The functions of the device, the module, and the corresponding modules described in this application may be executed cooperatively by a single chip or a combination of multiple chips, and the number of the multiple chip configurations is not limited in the scope of the present application. The chip may be, but is not limited to, a combination of a Processor (Processor), a Central Processing Unit (CPU), a Microprocessor (Microprocessor), a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Programmable Logic Device (PLD), and other devices, and is not limited in this Application. In another embodiment of the present application, the "device", "apparatus", "module", or a combination thereof may be a chip provided for an audio device (e.g., a mobile device, a wearable device), or an audio chip integrated or separated from a wired earphone, a wireless earphone, or a head-mounted device, and the variations are not intended to be limited in scope by the present application.
Referring to fig. 1, a block diagram of a bi-quad error control feedback active anti-noise system according to an embodiment of the present application is shown, in which:
referring to fig. 1, the present embodiment discloses a feedback active anti-noise system 100 for bi-level error control, which mainly includes an error receiver 10, an audio output device 20, an error shaper 30 and a feedback module 40.
The error receiving device 10 is mainly used for receiving an error sound source signal, the error receiving device 10 is generally disposed between a speaker and a human ear, and the audio signal received by the error receiving device 10 mainly includes a difference between the noise NS and a sound output by the speaker, where the difference is defined as the error sound source signal. The error receiving device 10 may be, for example, a microphone, a sound pickup or other devices capable of receiving ambient sound waves and further converting the ambient sound waves into analog and digital audio signals. In one embodiment, the error receiver 10 includes an error microphone 12, a preamplifier 14 connected to a rear end of the error microphone 12, an anti-aliasing filter 16 connected to a rear end of the preamplifier 14, and an analog-to-digital converter 18 connected to a rear end of the anti-aliasing filter 16. Finally, the analog digital-to-converter 18 outputs an error signal to the error shaper 30.
The audio output device 20 is mainly used for outputting a noise reduction signal for canceling the noise NS and the original audio. In an embodiment, the audio output device 20 may be a device for outputting sound, such as a speaker, a loudspeaker and an audio processing chip disposed correspondingly, where the output sound is defined as an audio signal. In an embodiment, the audio output device 20 sequentially includes a speaker 28, a power amplifier 26 connected to a front end of the speaker 28, a reconstruction filter 24 connected to a front end of the power amplifier 26, and a digital-to-analog converter 22 connected to a front end of the reconstruction filter 24. The dac 22 receives the noise reduction signal from the feedback module 40 and the original audio (not shown in the figure, the input position), which is music, voice or other sounds that have not entered the space and are not affected by the noise NS, and is not limited in this application.
The error shaper 30 is mainly used to reduce the high frequency noise of the error signal, and the error signal with reduced high frequency noise is defined as the error shaped signal. Referring to fig. 2, fig. 3, and fig. 4, a block diagram of an error shaper 30, a biquad filter, and a block diagram of a hierarchical arrangement of biquad filters of 1 to N orders according to the present application are shown as follows:
the input of the error shaper 30 is connected to the output of the error receiver 10 for receiving an error signal. In an embodiment, the error shaper 30 comprises, in sequence, a noise bandwidth detector 32, a coefficient corrector 34 having an input connected to the noise bandwidth detector 32, and a 1 to N-th order biquad filter 36 having an input connected to the coefficient corrector 34. Wherein, the input terminal of the noise bandwidth detector 32 is connected to the output terminal of the error receiving device 10; the other input end of the coefficient corrector 34 is connected to the error microphone 12, and a Frequency Detector (not shown) is disposed between the coefficient corrector 34 and the error microphone 12; an input terminal of each of the biquad filters 36 of order 1 to N is connected to the coefficient corrector 34, and specifically, another input terminal of the biquad filter 361 of order 1 of the biquad filter 36 of order 1 to N is connected to the error receiving apparatus 10. Finally, the nth order biquad filter 36N of the 1 to nth order biquad filters 36 outputs an error shaping signal to the feedback module 40.
The order of the 1-nth order biquad filter 36 is as follows, please refer to fig. 4: the output of the 1 st order biquad filter 361 is connected to the other input of the 2 nd order biquad filter 362; the output of the 2 nd order biquad filter 362 is connected to another input of the 3 rd order biquad filter 363, and so on, and the output of the N-1 th order biquad filter 36N-1 is connected to another input of the N th order biquad filter 36N.
The input end of the feedback module 40 is connected to the error shaper 30 and receives the audio signal, so as to perform adaptive operation on the received audio signal and the error shaped signal and utilize the generated inverse signal and noise cancellation to achieve the noise reduction effect, where the signal output by the feedback module 40 for canceling the noise NS is defined as a noise reduction signal. In one embodiment, referring to fig. 5, the feedback module 40 includes a mixer 42, an LMS operator 44(Least Mean Square Filter) having an input connected to an output of the mixer 42, and an Adaptive Filter 46(Adaptive Filter) having an input connected to the LMS operator 44. Wherein the other input of the LMS operator 44 is connected to the output of the error shaper 30; the other input terminal of the adaptive filter 46 is connected to the mixer 42, and the output terminal of the adaptive filter 46 is connected to the audio output device 20. In this embodiment, the signal input to the speaker 28 has a first secondary path filter 41 between the paths fed back to the mixer 42 for filtering the audio signal in advance; a second secondary path filter 43 is provided between the path of the output of the mixer 42 and the input of the LMS operator 44 to filter the mixed signal in advance. The first secondary path filter 41, the second secondary path filter 43 are used as a transfer function for estimating the actual path, so that the LMS operator 44 can generate a noise reduction signal with the same magnitude as the noise NS and opposite phase to the noise NS to the audio output device 20 after adjusting the coefficient of the adaptive filter 46.
The above description is directed to an embodiment of a hardware architecture of the present application, and the operation of the present application will be further described below with reference to fig. 3, fig. 4, fig. 5, and fig. 6, which are schematic control logic diagrams and flow charts of a bi-quad filter, a block diagram of a hierarchical configuration of a 1-N-th order bi-quad filter, and a bi-quad error control feedback active anti-noise system of the present application, and are shown in the following figures:
first, the noise NS and the audio signal are received by the error microphone 12 of the error receiving device 10, and the noise NS and the audio signal are converted into the error signal of digital audio by the error receiving device 10 to the error shaper 30 (step S201). When the system is started, the audio signal is not subjected to noise reduction processing, and the audio signal is the original audio signal.
The noise-bandwidth detector 32 of the error shaper 30 detects the bandwidth of the error signal and outputs a noise-bandwidth signal having the same bandwidth as the center frequency of the error signal to the coefficient corrector 34 (step S202). The center frequency is obtained from the noise bandwidth detector 32 via an error signal according to the following formula:
wherein, k is 0.... am-1; x (n) is the error signal inputted by the error receiving device in n stages, f (k) is the center frequency outputted by the noise bandwidth detector 32, f (k) has M outputs, M is the predetermined number of outputs.
The coefficient corrector 34 receives the error microphone signal and the noise bandwidth signal, and calculates a coefficient correction signal for adjusting the coefficient of the biquad filter to the 1 to N-th order biquad filter 36, so that the 1 to N-th order biquad filter 36 corrects the coefficient according to the bandwidth of the error signal (step S203). In other words, the coefficients of the biquad filter 36 of the present application 1 to nth order can be modified by the coefficient modifier 34 to adjust the high frequency noise to be modified. Referring to fig. 3, the coefficient corrector 34 corrects the coefficients of each biquad filter 361-36N according to the following formula:
wherein, w0Is a central angular frequency value, alpha is a natural frequency parameter, b0、b1、b2、a1、a2For the coefficients of the respective biquad filters 361-36N.
The aforementioned central angular frequency value w0And the natural frequency parameter α is obtained by the coefficient corrector 34 according to the following formula:
wherein f iskIs the center frequency, F, input by the noise bandwidth detector 32sIs the frequency of the error microphone signal input by the error microphone 12, Q is a predetermined quality parameter, w0Is a central angular frequency value, and alpha is a natural frequency parameter. The aforementioned quality parameter Q is determined based on quality factors; the natural frequency parameter α is determined based on the natural frequency factor.
Further, the 1 to N-th order biquad filter 36 corrects the coefficient according to the bandwidth of the received error signal, and eliminates the high frequency noise of the error signal of the next sample according to the corrected coefficient (x (N-1), x (N-2) are regarded as known parameters), and the N-th order biquad filter 36N outputs the error shaping signal (step S204). Each of the biquad filters 361-36N filters the error signal according to the following equation:
y(n)＝b0×x(n)+b1×x(n-1)+b2×x(n-2)-a1×y(n-1)-a2×y(n-2)；
wherein x (n), x (n-1), x (n-2) are error signals received at the nth, nth-1 and nth-2 time points, and y (n), y (n-1) and y (n-2) are nth orderThe error shaping signal outputted at the time points of the n-1 th order and the n-2 nd order, b0、b1、b2、a1、a2For the coefficients of the respective biquad filters 361-36N.
Further, the audio signal and the error-shaped signal passing through the first sub-path filter 41 are mixed by the mixer 42 of the feedback module 40 and output a mixed signal (step S205).
The LMS operator 44 updates the weight coefficient of the adaptive filter 46 by receiving the error shaping signal and the mixed signal passing through the second secondary path filter 43, so that the adaptive filter 46 adjusts the received mixed signal into a noise reduction signal having the same magnitude as the noise NS and the opposite phase, and the adaptive filter 46 outputs the noise reduction signal to the audio output device 20 (step S206).
Finally, the audio output device 20 uses the received noise reduction signal to eliminate the next-order noise NS, and converts the noise reduction signal and the original audio signal into an audio signal of analog audio (step S207). In other words, the audio signal achieves the noise reduction effect through the noise reduction signal of the previous stage, so that the original audio in the audio signal is not affected by the noise NS and enters the human ear.
In summary, compared with the prior art, the present application can reduce the high-frequency noise of the error signal, and can further avoid the operation divergence of the adaptive filter to reduce the noise reduction effect in addition to adjusting the eliminated high-frequency noise according to the requirement.
Although the present application has been described in detail, it should be understood that the above description is only an example of the present application, and not intended to limit the scope of the present application, i.e., the appended claims are intended to cover all such modifications and changes as fall within the true spirit and scope of the present application.
Claims (10)
1. A bi-quad error control feedback active anti-noise system, the system comprising:
an error receiving device for receiving the error sound source signal and outputting an error signal;
an audio output device for outputting an audio signal;
an error shaper, an input end of which is connected to the error receiving device to receive the error signal, the error shaper including a noise bandwidth detector, a coefficient corrector, an input end of which is connected to the noise bandwidth detector, and a 1 to N-order biquad filter, an input end of which is connected to the coefficient corrector, the noise bandwidth detector calculating a bandwidth of the error signal, the coefficient corrector correcting coefficients of the 1 to N-order biquad filter according to the bandwidth of the error signal, the 1 to N-order biquad filter eliminating high-frequency noise of the error signal of a next sample according to the corrected coefficients and outputting an error shaping signal; and
a feedback module, an input end of the feedback module is connected to an output end of the error shaper and receives the audio signal, an output end of the feedback module is connected to the audio output device, the feedback module includes a mixer, an LMS operator whose input end is connected to an output end of the error shaper and an output end of the mixer, and an adaptive filter whose input end is connected to an output end of the LMS operator and an output end of the mixer, an input end of the mixer is connected to an output end of the error shaper and receives the audio signal, the mixer mixes the error shaped signal and the audio signal and outputs a mixed signal, the LMS operator updates a weight coefficient of the adaptive filter according to the received error shaped signal and the mixed signal, the adaptive filter outputs a noise reduction signal to the audio output device after filtering the mixed signal according to the updated weight coefficient, and the adaptive filter outputs a noise reduction signal to the audio output device according to the updated weight coefficient And (6) discharging the device.
2. The system of claim 1, wherein the error receiving device comprises an error microphone, a preamplifier coupled to a rear end of the error microphone, an anti-aliasing filter coupled to a rear end of the preamplifier, and an analog-to-digital converter coupled to a rear end of the anti-aliasing filter.
3. The system of claim 1, wherein the audio output device comprises a speaker, a power amplifier connected to a front end of the speaker, a reconstruction filter connected to a front end of the power amplifier, and a digital-to-analog converter connected to a front end of the reconstruction filter.
4. The system of claim 2, wherein an input of the noise bandwidth detector is connected to the error receiving device to detect a bandwidth of the error signal and output a noise bandwidth signal having a bandwidth equal to a center frequency of the error signal;
wherein, the input end of the coefficient corrector is connected to the error microphone to receive an error microphone signal, and calculates and outputs a coefficient correction signal for adjusting the coefficient of the biquad filter to the 1 to N-order biquad filter according to the error microphone signal and the noise bandwidth signal;
wherein, the input end of the 1 st order biquad filter in the 1 st to N th order biquad filters is connected to the error receiving device to receive the error signal, and the 1 st to N th order biquad filters update coefficients according to the coefficient correction signal and output the error integer signal by the N th order biquad filter in the 1 st to N th order biquad filters after correcting the error signal of the next sampling according to the coefficients.
5. The system of claim 4, wherein each of the biquad filters the error signal according to the following equation:
y(n)＝b0×x(n)+b1×x(n-1)+b2×x(n-2)-a1×y(n-1)-a2×y(n-2)；
wherein x (n), x (n-1), x (n-2) are error signals received by the nth, the nth-1 and the nth-2 time points, y (n), y (n-1) and y (n-2) are the error integer signals output by the nth, the nth-1 and the nth-2 time points, b0、b1、b2、a1、a2For each of said biquad filteringThe coefficients of the machine.
6. The system of claim 5 wherein said coefficient modifier modifies the coefficients of each of said biquad filters according to the following equation:
wherein, w0Is a central angular frequency value, alpha is a natural frequency parameter, b0、b1、b2、a1、a2For each of the biquad filter coefficients.
7. The system of claim 6, wherein the central angular frequency value and the natural frequency parameter are obtained by the coefficient modifier according to the following equations:
wherein f iskIs the center frequency, F, input by the noise bandwidth detectorsFor the frequency input by the error microphone, Q is a predetermined quality parameter, w0Is a central angular frequency value, and alpha is a natural frequency parameter.
8. The system of claim 7 wherein the center frequency is derived from the error signal by the noise bandwidth detector according to the following equation:
wherein, k is 0.... am-1; x (n) is the error signal inputted by the error receiving device in n stages, f (k) is the center frequency outputted by the noise bandwidth detector, f (k) has M outputs, M is the preset output number.
9. The system of claim 7, wherein the quality parameter is determined based on a quality factor and the natural frequency parameter is determined based on a natural frequency factor.
10. The system of claim 1, wherein a first secondary path filter is provided between the paths of the output of the audio output device and the input of the mixer; and a second secondary path filter is arranged between the paths of the output end of the mixer and the input end of the LMS operator.
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| Application Number | Priority Date | Filing Date | Title |
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| TW109127584 | 2020-08-13 | ||
| TW109127584A TW202207214A (en) | 2020-08-13 | 2020-08-13 | Biquad error controling feedback type active noise cancellation system |
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| TWI822031B (en) * | 2022-05-05 | 2023-11-11 | 律芯科技股份有限公司 | Intelligent biquad feedforward active noise cancellation system |
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| TWI822031B (en) * | 2022-05-05 | 2023-11-11 | 律芯科技股份有限公司 | Intelligent biquad feedforward active noise cancellation system |
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