CN107666637B - Self-adjusting active noise elimination method and system and earphone device - Google Patents
Self-adjusting active noise elimination method and system and earphone device Download PDFInfo
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- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
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Abstract
A self-adjusting active noise eliminating method, system and earphone device, the earphone device is set on a measuring tool, the measuring tool is used to receive the audio frequency output by earphone device, it can simulate the sound heard by human ear, the self-adjusting active noise eliminating system obtains the environment noise signal from the microphone in earphone device, the signal generated by system is the reverse noise signal for offsetting environment noise signal, it is used to suppress the environment noise signal continuously received by loudspeaking unit, then the output sound mixing signal can be defined as error signal, in an adjusting mode, the error signal received by self-adjusting tool can be used to update the self-adjusting active noise eliminating parameter, when the error signal is lower than a default threshold, the adjusting process is finished, finally the parameter can be stored as the default value of earphone device of user mode.
Description
Technical Field
The present invention relates to a technique for providing noise reduction parameters of a noise reduction headphone, and more particularly, to a self-adjusting active noise cancellation method and system through ambient noise simulation and error correction, and a headphone apparatus using the noise reduction parameters generated by the system.
Background
The operation principle of a conventional Noise reduction earphone with Active Noise Control (ANC) is to fabricate a sound receiving unit on the earphone for receiving external Noise, and an internal signal processing system can generate signals for destroying external Noise signals (amplitude and frequency) in cooperation with software and hardware processing, for example, generate signals with the same amplitude and frequency but opposite phase to those of the Noise, so as to cancel the external Noise in the Noise reduction earphone, thereby achieving the effect of eliminating the Noise.
An active noise control system applied in an active noise reduction earphone is generally divided into two architectures, namely a feed-forward control architecture and a feedback control architecture, wherein the feedback control architecture has a stability problem, and therefore, much time is required to select electronic components and adjust the gain of a controller in the mass production process; the feedforward control architecture has no stability problem, but still requires time to teach to achieve the desired performance, and the noise reduction effect is not as good as the feedback architecture.
In order to take advantage of both the feedforward control and the feedback control in the prior art, a hybrid architecture has been proposed, which can achieve better noise reduction effect, but because each set of earphone requires four microphones, the complexity of the control circuit is relatively increased, and the overall cost is increased due to the circuit design and the use of electronic components.
Fig. 1 shows a schematic diagram of an active noise reduction earphone in the prior art, which schematically shows a earphone housing 100 covering a human ear 10, and a microphone inside and outside the earphone device, and an in-earphone speaker 103 included in the earphone housing 100, wherein the in-earphone microphone 105 is a microphone for receiving an error signal (error) and the out-earphone microphone 107 is a microphone for receiving a reference signal (reference).
With the active noise reduction architecture, the earphone device receives a reference signal with the microphone 107 outside the ear cup, and receives noise (error signal) inside the ear cup 100 with the microphone 105 inside the ear cup, and the error signal is fed back to the Digital Signal Processor (DSP) 101. the DSP 101 can automatically adapt the parameters of a digital Filter (e.g., a digital FIR Filter) in order to minimize the noise transmitted to the human ear 10.
Disclosure of Invention
The invention provides a self-adjusting active noise elimination method, a system and an earphone device for providing noise adjustment parameters, wherein a related system records the noise adjustment parameters corresponding to the earphone device when the earphone leaves the factory according to environmental noise simulation and an error adjustment signal obtained by an error radio device, so that the earphone device with the active noise reduction function can still take the advantages of two architectures of a feed-forward type control and a feedback type control into consideration under the condition of not increasing the cost of excessive materials.
According to an embodiment of the self-adjusting active noise cancellation method, the proposed self-adjusting active noise cancellation system preferably obtains an ambient noise signal generated by a speaker simulation from the earphone device to form a reference signal, then performs an active noise reduction filtering process, uses a set of self-adjusting active noise cancellation parameters to generate a filtered signal after filtering the reference signal, and outputs the filtered signal to the earphone device, which outputs the filtered signal to cancel the ambient noise signal, and the residual value formed is received by an audio measurement unit as an error signal for evaluating noise reduction performance of the self-adjusting active noise cancellation system.
Specifically, according to an embodiment, when the self-adjusting active noise cancellation system evaluates the error signal, it is determined whether the error signal is lower than a threshold, if the error signal is higher than or equal to the threshold, an adaptive algorithm is executed to update the self-adjusting active noise cancellation parameters for adjusting the filter parameters in the active noise reduction filtering process, and after repeating the above-mentioned process, the self-adjusting active noise cancellation parameters are continuously updated until the error signal is lower than the threshold, the self-adjusting active noise cancellation parameters are determined, and the self-adjusting active noise cancellation parameters when the tested earphone device leaves the factory are formed after being stored.
Furthermore, the environmental noise signal is broadcasted by a loudspeaker simulating the environmental noise and then received by a sound receiving unit of the earphone device to form a reference signal. The adaptive algorithm employs a normalized least mean square algorithm.
Specifically, the self-adjusting active noise cancellation method is applicable to an earphone device, and self-adjusting active noise cancellation parameters are stored in a memory of the earphone device and become factory values of the earphone device.
Preferably, the main assembly of the self-adjusting active noise cancellation system described in the embodiments includes an input/output unit for receiving the environmental noise signal obtained from the earphone device to form a reference signal, outputting the filtered signal to the earphone device, and receiving an error signal generated by an audio measuring unit; the system comprises a filtering unit, a filtering unit and a control unit, wherein the filtering unit adopts a filtering equation and performs filtering by using a group of self-adjusting active noise elimination parameters to generate a filtered signal; the system comprises an adaptive calculation unit for calculating the error signal to obtain the number of the filter equation and determining the self-adjusting active noise elimination parameter; the system includes a storage unit for storing the set of self-adjusting active noise cancellation parameters.
Furthermore, the input/output unit includes a radio interface unit, the reference signal is connected to the radio interface unit via a signal line, the input/output unit includes a line connection interface, and the self-adjusting active noise elimination system receives the error signal via the line connection interface.
Further, in the configuration of the self-adjusting active noise cancellation system, the external device includes an audio measuring unit simulating ambient noise, which may be an artificial ear measuring system simulating human ears, for receiving audio output by the earphone device.
Further, the self-adjusting active noise elimination system judges the noise reduction efficiency of the system by evaluating the error signal, evaluates whether the error signal meets the requirement by a threshold, repeatedly generates self-adjusting active noise elimination parameters until the error signal meets the requirement, and stores the corresponding self-adjusting active noise elimination parameters as the factory value of the earphone device.
Preferably, the earphone device comprises a storage unit, a digital signal processor, a radio unit and a loudspeaker unit; the digital signal processor introduces self-adjusting active noise elimination parameters in the storage unit by an active noise control filter equation to generate a reverse noise signal for canceling the external environment noise.
Furthermore, the system also comprises a digital signal processor, a radio unit and a loudspeaker unit; the digital signal processor introduces self-adjusting active noise elimination parameters in the storage unit by an active noise control filter equation to generate a reverse noise signal for counteracting the external environment noise.
For a further understanding of the techniques, methods and functions of the present invention, reference should be made to the following detailed description of the invention, taken in conjunction with the accompanying drawings, which are included to provide a further understanding of the invention, and to the specific features and advantages thereof, and to the accompanying drawings, which are included to provide a further understanding of the invention.
Drawings
Fig. 1 shows a schematic diagram of an active noise reduction earphone in the prior art;
FIG. 2A is a schematic diagram of an embodiment of a self-adaptive active noise cancellation system according to the present invention;
FIG. 2B shows a diagram of a transfer function embodiment for implementing the self-adjusting active noise cancellation system of the present invention;
FIG. 3 schematically depicts a headphone set that derives noise reduction parameters generated by a self-adjusting active noise cancellation system;
FIG. 4 is a block diagram of a circuit embodiment of a self-tuned active noise cancellation system according to the present invention;
FIG. 5 is a diagram illustrating an overall setup embodiment of the self-tuned active noise cancellation system of the present invention;
the flow chart of fig. 6 describes the flow chart of an embodiment of the self-adjusting active noise elimination method of the present invention.
Detailed Description
The embodiments described herein relate to a self-adjusting active noise cancellation method and system through ambient noise simulation and error correction, and a headphone apparatus using the self-adjusting active noise cancellation parameters for noise reduction generated by the system. One of the objectives of the present invention is to record noise adjustment parameters corresponding to an earphone device when the earphone device leaves a factory, so that the earphone device with an active noise reduction function can still take advantages of two active noise reduction circuit architectures of the aforementioned feed forward control and feedback control into account without adding a noise reduction microphone component.
Referring to the schematic diagram shown in fig. 2A, the basic structure of the self-adjusting active noise cancellation system proposed in the present specification includes a digital signal processor 201, a sound receiving unit 203 for receiving external noise, and a speaker unit 205 for playing sound in a headphone cover 202, and an audio sound receiving unit 207 is disposed in the measurement fixture 22.
When the self-adjusting active noise cancellation system is operating, the earphone device 20 is mounted on the measuring fixture 22, which includes a line-in (not shown in this schematic diagram) for connecting the audio receiving unit 207 of the measuring fixture 22 to the line of the earphone device 20. The digital signal processor 201 can obtain the external environment noise received by the sound receiving unit 203 as a reference signal (reference signal), and perform analog-to-digital conversion to form a noise signal; an error signal (error signal) measured by the measuring tool 22 is received from the audio receiving unit 207 through the line access interface, and the error signal provides a system for evaluating the current noise reduction performance. The dsp 201 performs Active Noise Control (ANC), calculates an adaptive algorithm (e.g., Normalized least mean Square algorithm) to determine self-adjusted Active noise cancellation parameters, the self-adjusted Active noise cancellation parameters are introduced into the filter equation, the reference signal is calculated by the filter equation under the filter mechanism to obtain a filtered signal (filtered noise), and an inverse noise signal is generated and outputted to the speaker unit 205 for broadcasting. When the speaker unit 205 in the earphone device 20 broadcasts the reverse noise signal, the external environment noise continuously received can be cancelled, and the effect of noise reduction can be achieved after the external environment noise is cancelled. As mentioned above, the most commonly used algorithm is the Filter-X LMS algorithm derived based on LMS.
Under the self-adjusting active noise elimination mechanism, the speaker unit 205 outputs the inverse noise signal generated by filtering to counteract the continuously received environmental noise, and the sound signal generated by the cancellation of the two is received by the audio reception unit 207 in the measurement fixture 22 to output an error signal, so as to determine whether the error signal is lower than a system-set noise threshold, and if the calculation is still to be continued, the digital signal processor 201 executes the active noise control again to adapt the calculation to determine another self-adjusting active noise elimination parameter until the error signal is lower than the system-set noise threshold.
Fig. 2B shows a diagram of an embodiment of a transfer function for implementing the self-adjusting active noise cancellation system of the present invention.
In the operation of the self-adjusting active noise elimination system, the environmental noise simulation unit simulates the environmental noise to become the reference signal x (n) inputted into the self-adjusting active noise elimination system, and on the path (first path) of the main signal propagation, the reference signal x (n) is transferred via the housing or ear cover (ear cover transfer function P) of the earphone device, the ear cover transfer function P represents the space response of the reference signal x (n) converted into the noise signal d (n) via the propagation path, and the noise signal d (n) to be eliminated is formed after the transfer.
Another path (second path) of the self-tuned active noise cancellation system is that the aforementioned ambient noise forming reference signal x (n) is filtered (filter parameter W) by an automatically adapted digital filter, which introduces a set of filter parameters W (i.e. self-tuned active noise cancellation parameters) to generate a filtered signal y (n), wherein the actions include analog-to-digital conversion, signal reconstruction, power adjustment, etc. The transfer function S is used to estimate the impulse response of the path, and the impulse response estimated by the transfer function S covers various electronic components required for prediction on the path, such as a microphone, a preamplifier, a pre-low pass filter, an analog-to-digital converter, and/or various electronic components required for the speaker to output sound, such as a digital-to-analog converter, a post-low pass filter, etc., which are not shown in the figure, for the equivalent transfer function of the second path. The filtered signal y (n) is an inverse noise signal, which is an active noise reduction signal d' (n) formed on this path after the transfer function S.
The difference between the noise signal d (n) and the active noise reduction signal d '(n) obtained by the error calculation 211 is the error signal e (n), which is the estimated value of the residual noise, i.e. the noise left after the reverse noise signal (e.g. d' (n)) generated and outputted by the active noise reduction mechanism and the noise signal to be mainly removed (e.g. d (n)) cancel each other out, can be used as the basis for estimating the noise reduction performance of the system and become the self-adjusting active noise removal parameter feedback 209, and the generated self-adjusting active noise removal parameter is used as the basis for adjusting the filter parameter to provide the updated filter parameter W.
In operation, the above transfer operation is repeated to repeatedly obtain new self-adjusting active noise elimination parameters, and the filter parameter W and the obtained error signal e (n) are continuously updated until a better error value and a corresponding self-adjusting active noise elimination parameter required by the system are reached, and the better error value and the corresponding self-adjusting active noise elimination parameter are stored and then used as the default filter parameter W of the tested earphone device.
Fig. 3 illustrates a headphone set 20 optimized by the self-adjusting active noise reduction system according to the present invention, that is, a system provided with the self-adjusting active noise reduction parameters, the headphone set 20 stores the self-adjusting active noise reduction parameters generated by the self-adjusting active noise reduction system in its memory before the headphone set 20 is shipped, and the headphone set 20 is worn on the ear 30, and the headphone housing 202 is schematically illustrated as the ear 30 covered on the headphone set.
In operation, the earphone device 20 is connected to the external sound source 32 through a signal line 321 (corresponding to a line-in interface), such as an interface for receiving sound source, which can input audio from the external sound source 32 to the earphone device 20. The digital signal processor 201 performs the optimized noise reduction processing by introducing the self-adaptive active noise cancellation parameters obtained as described above. In the process, the earphone device 20 obtains the external environment noise through the sound receiving unit 203, and the digital signal processor 201 introduces the self-adjusting active noise cancellation parameters in the storage unit by using an Active Noise Control (ANC) filtering equation to generate an inverse noise signal for canceling the external environment noise, thereby providing an active noise reduction function. Then, the speaker unit 205 outputs a reverse noise signal to cancel the external environmental noise, and the canceled sound signal (including the sound signal generated by the external sound source) is output to the human ear 30.
The self-adjusting active noise cancellation system described above in the tuning mode (tuning phase) as illustrated in fig. 2A and 2B can be implemented by a separate circuitry that generates the self-adjusting active noise cancellation parameters for implementing the noise reduction system in the earphone device, one embodiment of which is illustrated in fig. 4.
The self-adjusting active noise cancellation system 40 may be implemented as a noise reduction system in a headphone set, such an external noise cancellation system being implemented in a tuning mode, i.e. using in-headphone noise reduction circuitry, wherein the functionality may be implemented by a plurality of different circuit elements. The external connection interface of the self-adjusting active noise cancellation system 40 includes a radio interface unit 402(MIC), a SPEAKER interface unit 401(SPEAKER), and a Line-In interface unit 403(Line-In), and the main circuit components for performing signal processing are a filtering unit 407, an analog-to-digital conversion unit 404, an adaptive operation unit 405, and a storage unit 406 for storing data.
When the self-tuned active noise cancellation system 40 is in operation, the external environment generates simulated ambient noise through the ambient noise simulation unit 44, the ambient noise is received by a microphone of the tested earphone device (not shown in the figure, which may be disposed on the audio measurement unit 42) that receives the external noise, and is connected to the self-tuned active noise cancellation system 40 through a signal line, and a reference signal 412 is formed and is shown as being transmitted to the self-tuned active noise cancellation system 40, and the reference signal 412 is input to the system through the radio interface unit 402 of the self-tuned active noise cancellation system 40.
After the reference signal 412 is converted into a digital signal by the in-system analog-to-digital conversion unit 404, a signal generated by the filtering equation operated by the filtering unit 407 (using a set of self-adjusting active noise cancellation parameters) is converted into an analog signal by the analog-to-digital conversion unit 404, the formed signal is a reverse noise signal for canceling ambient noise, and then the signal is output as a filtered signal 411 through the speaker interface unit 401 and is input to the headphone device to be tested.
The filtered signal 411 is the result of filtering the reference signal 412 by the system, using a default set or previously processed set of self-adjusting active noise cancellation parameters. The filtered signal 411 is outputted to the earphone device for playing, so as to cancel the environmental noise generated by the environmental noise simulation unit 44, and the residual value left after the main noise signal to be eliminated (such as the reference signal 412) is cancelled, which is received by the audio measurement unit 42 to form an error signal 413, which is inputted to the self-adjusting active noise elimination system 40 via the line access interface unit 403.
It should be noted that the line access interface unit 403 is an interface of the audio input headphone device, in the tuning mode, the error signal 413 is input into the self-adaptive active noise cancellation system 40 through the line access interface unit 403, and after being converted into a digital signal by the analog-to-digital conversion unit 404, the digital error signal is computed by an adaptive algorithm unit 405 to adjust the coefficients of the active noise control filter equation therein, so as to form a set of self-adaptive active noise cancellation parameters. In one embodiment, the instantaneous squared error of the error signal (instanceousssquared error) is minimized by adjusting the self-adjusting active noise cancellation parameters, and one of the methods used is to adjust the coefficients in the adaptive algorithm using a gradient estimation (Stochastic gradient) or Least Mean method (Least Mean Square) as described above.
When the noise reduction performance of the system is optimized by the adaptive calculation, a set of self-adjusting active noise cancellation parameters can be determined, and the self-adjusting active noise cancellation parameters are substituted into the filtering equation, so that the next wave reference signal generated by the earphone device can be calculated by the filtering equation to obtain an optimized filtered signal 411, and then the optimized filtered signal is output through the speaker interface unit 401.
After the filtered signal formed by filtering the updated self-adjusting active noise cancellation parameter is outputted to the earphone device, the effect of canceling the environmental noise is achieved, an error signal 413 is generated by receiving sound from the audio measuring unit 42, the self-adjusting active noise cancellation system 40 evaluates the error signal 413, and if the self-adjusting active noise cancellation parameter meets the requirement set by the system, the related self-adjusting active noise cancellation parameter is stored in the storage unit 406.
In one embodiment, after the self-adaptive active noise cancellation system 40 receives the error signal 413, it may perform an evaluation, for example, evaluate the error signal 413 by a threshold to determine whether it is optimal or has achieved a required noise reduction performance, if the error signal 413 does not achieve the required noise reduction performance, the above processing is continued, and the self-adaptive active noise cancellation parameters are calculated and updated until the error signal 413 is evaluated to achieve the noise reduction requirement, and the corresponding self-adaptive active noise cancellation parameters are stored and applied to the corresponding tested earphone device.
The audio measuring unit 42 is implemented as a measuring tool, which implements a set of artificial ear measuring system (model: ITU-P57type 2) simulating human ears, and has a speaker assembly with a hole at one end for receiving sound internally, and can output an error signal in analog form.
Fig. 5 is a diagram illustrating an overall setup embodiment of the self-adjusting active noise cancellation system 50 according to the present invention, wherein the self-adjusting active noise cancellation system can be implemented as a circuit system of an earphone device with an active noise reduction function, which can be implemented as an Integrated Circuit (IC), an electronic circuit, or firmware.
In the implementation situation diagram of the self-adjusting active noise cancellation system 50, a set of speakers is displayed to continuously broadcast the audio signals simulating the environmental noise, so as to realize the environmental noise simulation units 55,55 ' in the self-adjusting active noise cancellation system of the present invention, and a headphone device 53,53 ' to be tested having two ears is disposed on a measuring fixture, the headphone device 53,53 ' itself has a sound receiving unit 531,531 ' for receiving external sound signals (noise), and the measuring fixture is an artificial ear measurement system simulating human ears, so as to realize the audio measurement units 51,51 ' in the self-adjusting active noise cancellation system of the present invention, and the speakers of the headphone devices 53,53 ' face the sound receiving holes (downward in this example) of the audio measurement units 51,51 ', so that the audio measurement units 51,51 ' can receive the audio signals output by the headphone devices 53,53 ', including the received environmental noise and the noise-suppressed signals obtained by the noise reduction processing. The audio measurement unit 51, 51' then outputs an error signal 511,512 via the output interface to the self-adjusting active noise cancellation system 50.
In this configuration, the input/output unit 501 of the self-adjusting active noise cancellation system 50 includes several interfaces implemented on the earphone device, such as a speaker interface unit (fig. 4, 401) for outputting audio, a radio interface unit (fig. 4, 402) for receiving external noise signals, and a line access interface unit (fig. 4, 403) for receiving external audio (e.g. music, voice). The input/output unit 501 receives the environmental noise signal from the earphone devices 53, 53' through the circuit, and forms a reference signal 513 in the self-adjusting active noise cancellation system 50. The input/output unit 501 is used to output the filtered signal 514 generated by the self-adaptive active noise cancellation system 50 to form an inverse noise signal sufficient to cancel some or all of the noise. The input/output unit 501 receives the error signal generated by the audio measuring unit 51, 51' through the line access interface. In the user mode, i.e. the non-calibration phase, the line access interface is an interface for receiving audio on the headset.
The self-adjusting active noise cancellation system 50 includes an analog-to-digital conversion unit 503 that performs analog-to-digital signal conversion, including converting input analog audio to digital audio, and converting digital audio to output analog audio.
The adaptive computing unit 507 is configured to compute an adaptive algorithm, such as the Normalized Least Mean Square (LMS) algorithm, for computing the received error signal to obtain the coefficients of the filter equation to determine the self-adjusting active noise cancellation parameters.
The filtering unit 505 introduces a set of self-adjusting active noise cancellation parameters to be introduced into the filtering equation, in this case, the reference signal is filtered to obtain a filtered signal, and an inverse noise signal for canceling the environmental noise is generated.
The self-adjusting active noise elimination system 50 has a storage unit 509, which is a memory for recording self-adjusting active noise elimination parameters adjusted by the system in the self-adjusting active noise elimination system 50 in the adjustment mode; if in the user mode, the storage unit 509, i.e., the headphone set 53,53 ', stores therein the self-adjusting active noise cancellation parameters for performing active noise reduction as the headphone set 53, 53'.
When the system is in operation, the earphone devices 53,53 'continuously receive the analog noise generated by the environmental noise simulation units 55, 55', the self-adjusting active noise cancellation system 50 is introduced into the system through the input/output unit 501 to be the reference signal 513, the reference signal 513 is processed in the system 50, including analog-to-digital conversion, and is filtered by the filtering unit 505 according to a self-adjusting active noise cancellation parameter to form a filtered signal 514, which is output to the earphone devices 53,53 ', and is output to the speaker units of the earphone devices 53, 53', and the played signal includes the continuously received noise. When the headphone assembly 53,53 'cancels the ambient noise signal by the filtered signal, the resulting residual is received by the audio measurement unit 51, 51' and output as an error signal 511,512 that provides an estimate of the noise reduction performance of the self-adjusting active noise cancellation system 50.
Thus, the self-adaptive active noise cancellation system 50 can estimate the error signals 511,512 by a threshold, and when the error signals do not meet the condition, the error signals are processed by the adaptive algorithm unit 507 each time to generate a new set of self-adaptive active noise cancellation parameters, and the filtered signals are continuously generated; when the condition below the set threshold is met, it indicates that a preferable self-adjusting active noise cancellation parameter is obtained, and the parameter can be stored as a factory value of the earphone device 53, 53' by the storage unit 509.
The filtering unit 505 may be implemented as a Finite Impulse Response (FIR) filter for performing active noise control filtering.
The flow chart of fig. 6 describes the flow chart of an embodiment of the self-adjusting active noise elimination method of the present invention.
In step S601, the earphone device is provided with a sound receiving unit for receiving external environmental noise, for example, an environmental noise signal generated by the environmental noise simulation unit, and the environmental noise signal is used as a reference signal of the tuning system and output to the self-adjusting active noise cancellation system. The sound receiving unit of the earphone device is a microphone arranged on the shell of the earphone device and used for receiving sound outwards, and the environmental noise simulation unit is a loudspeaker used for simulating environmental noise.
In step S603, the related calibration circuit obtains the environmental noise received by the earphone device through the connected signal line as a reference signal of the self-adjusting active noise cancellation system. Next, in step S605, filtering is performed in the self-adjusting active noise cancellation system, for example, a Finite Impulse Response (FIR) digital filter is used, after receiving the reference signal, the system performs an active noise reduction filtering process, such as active noise control filtering (ANCfiltering), to generate a filtered signal, wherein the active noise reduction filtering process performs filtering with a set of self-adjusting active noise cancellation parameters, and if the active noise reduction is performed for the first time, the set of self-adjusting active noise cancellation parameters is an initial value.
The filtered signal is preferably an inverse noise signal, and is output to the associated circuitry of the earphone device, as shown in step S607, where the filtered signal, after being output by the earphone device, can cancel the continuously received ambient noise, and the resulting residual value is output by the speaker unit of the earphone device and received by the audio measurement unit, as shown in step S609, where the system then receives the generated noise-reduced error signal from the audio measurement unit. The audio output by the earphone device is the noise-reduced audio which is calculated by the specific self-adjusting active noise elimination parameter, and after the audio is received by the audio measuring unit of the simulated human ear, the system can obtain the noise signal received by the human ear, which is the residual value after noise reduction, and the error signal is formed. The audio measuring unit generates an error signal for monitoring the noise reduction performance of the whole earphone system, so that the error signal can be used as a basis for adjusting the number of filter stages in the earphone device.
Then, a threshold is used to evaluate the noise reduction quality, in step S611, the self-adjusting active noise cancellation system determines whether the error signal is lower than the threshold set by the system, so as to determine whether the error signal is the filtering parameter optimized for the earphone device.
When evaluating the error signal, mainly determining whether the error signal is lower than a threshold set by a system, if the error signal is higher than or equal to the threshold, in step S613, executing the adaptive algorithm to generate a new set of self-adjusting active noise cancellation parameters to update the set of self-adjusting active noise cancellation parameters, in step S615, the updated self-adjusting active noise cancellation parameters can be used to adjust filter parameters in the active noise reduction filtering process, the process returns to step S603, and steps S603 to S611 are repeated, including steps of active noise reduction filtering, outputting filtered signals, receiving error signals, evaluating error signals, and updating the self-adjusting active noise cancellation parameters; when the error signal is lower than the threshold, in step S617, the system stores the corresponding set of self-adjusting active noise cancellation parameters as the self-adjusting active noise cancellation parameters for the earphone device.
Through the continuous loop operation of the flow disclosed in fig. 6, the received reference signal is operated by adjusting the self-adjusting active noise cancellation parameter generated each time, and the noise is outputted and measured until the measured error signal is lower than a specific threshold, that is, the adjusted self-adjusting active noise cancellation parameter obtained next time is stored, and particularly stored in the memory of the earphone device, as the factory value for performing noise reduction of the sub-earphone device.
In the above, according to the self-adjusting active noise cancellation method and the related system carried by the specification, the main idea is to move the microphone of the general active noise reduction earphone device for receiving the noise in the earphone to the measuring jig to simulate the hearing of the human ear, and to use the framework of the mixed feed-forward and feedback active noise control system in the prior art, and to calculate the filter parameter by using the adaptive algorithm, that is, the noise reduction parameter outputted by the self-adjusting active noise cancellation system, and to obtain the optimized noise suppression effect after iteration, that is, the noise reduction parameter is stored in the memory in the earphone device, so as to realize the effect like the feedforward control active noise control framework, for example, the noise reduction effect of four microphones can be achieved by using two microphones according to the present invention.
The above-mentioned embodiments are merely preferred embodiments of the present invention, and all equivalent changes and modifications made within the scope of the claims should be covered by the present invention.
Claims (9)
1. A self-adjusting active noise elimination method is executed in a self-adjusting active noise elimination system and used for generating self-adjusting active noise elimination parameters when an earphone device leaves a factory, the earphone device is arranged on a measuring jig, and the method is characterized by comprising the following steps:
obtaining an environmental noise signal from a radio unit of an earphone device to form a reference signal;
performing an active noise reduction filtering process to generate a filtered signal after filtering the reference signal, wherein the active noise reduction filtering process performs filtering with a set of self-adjusting active noise cancellation parameters;
outputting the filtered signal to the earphone device, outputting the filtered signal by the earphone device to offset the environmental noise signal, and receiving the residual value formed after offset by an audio measuring unit in the measuring jig to form an error signal;
receiving an error signal output by the audio measuring unit; and
evaluating the error signal, determining whether the error signal is below a threshold, if the error signal is above or equal to the threshold, executing an adaptive algorithm to update the set of self-adjusting active noise cancellation parameters for adjusting filter parameters in the active noise reduction filtering process, repeating the steps of the active noise reduction filtering process, outputting the filtered signal, receiving the error signal and evaluating the error signal, and updating the set of self-adjusting active noise cancellation parameters; when the error signal is lower than the threshold, the corresponding set of self-adjusting active noise elimination parameters is obtained, and the set of self-adjusting active noise elimination parameters is stored in a memory of the earphone device and becomes a factory value of the earphone device.
2. The self-adjusting active noise cancellation method of claim 1, wherein the ambient noise signal is broadcast by a speaker simulating ambient noise and received by a sound receiving unit of the earphone device to form the reference signal.
3. The method of claim 1 wherein the adaptive algorithm uses a normalized least mean square algorithm.
4. A self-adjusting active noise elimination system is used for generating self-adjusting active noise elimination parameters when an earphone device leaves a factory, the earphone device is arranged on a measuring jig, and the system is characterized by comprising:
an output/input unit for receiving the environmental noise signal from an earphone device and forming a reference signal in the self-adjusting active noise elimination system; outputting the filtered signal generated by the self-adjusting active noise elimination system; and receiving an error signal generated from an audio measurement unit;
a filtering unit, using a filtering equation, performing filtering with a set of self-adjusting active noise cancellation parameters, filtering the reference signal and generating the filtered signal;
an adaptive calculation unit for calculating the error signal to obtain the coefficient of the filter equation and determining the set of self-adjusting active noise elimination parameters;
a storage unit for storing the set of self-adjusting active noise cancellation parameters as self-adjusting active noise cancellation parameters for performing active noise reduction of the earphone device;
the self-adjusting active noise elimination system outputs the filtered signal to the earphone device through the input/output unit, the earphone device cancels the environmental noise signal through the filtered signal, a residual value formed after cancellation is received by the audio measuring unit in the measuring jig to form an error signal, and the self-adjusting active noise elimination system receives the error signal output by the audio measuring unit; the self-adjusting active noise elimination system evaluates the error signal, judges whether the error signal is lower than a threshold, if the error signal is higher than or equal to the threshold, executes an adaptive algorithm to update the set of self-adjusting active noise elimination parameters to adjust the filter parameters in the active noise reduction filtering processing, repeats the steps of the active noise reduction filtering processing, outputting the filtered signal, receiving the error signal and evaluating the error signal, and updates the set of self-adjusting active noise elimination parameters; when the error signal is lower than the threshold, the corresponding set of self-adjusting active noise elimination parameters is obtained, and the set of self-adjusting active noise elimination parameters is stored in a memory of the earphone device and becomes a factory value of the earphone device.
5. The self-adjusting active noise cancellation system of claim 4, wherein the input/output unit comprises a radio interface unit, and the reference signal is coupled to the radio interface unit via a signal line.
6. The self-adjusting active noise cancellation system of claim 4, wherein the input/output unit includes a line access interface, the self-adjusting active noise cancellation system receiving the error signal through the line access interface.
7. The self-adjusting active noise cancellation system of claim 4, 5 or 6, wherein said audio measurement unit is implemented as an artificial ear measurement system simulating a human ear.
8. An earphone device, comprising a storage unit for storing the self-adjusting active noise cancellation parameters generated by the self-adjusting active noise cancellation method according to claim 1.
9. The earphone device of claim 8, further comprising a digital signal processor, a radio unit, and a speaker unit; the digital signal processor introduces self-adjusting active noise elimination parameters in the storage unit by an active noise control filter equation to generate a reverse noise signal for canceling the external environment noise.
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| CN108551603A (en) * | 2018-02-28 | 2018-09-18 | 东莞市晨新电子科技有限公司 | A kind of noise cancelling headphone and test and the method for adjusting the earphone noise reduction parameters |
| CN109741727B (en) * | 2019-01-07 | 2020-11-06 | 哈尔滨工业大学（深圳） | Active noise reduction earphone based on active noise control algorithm, noise reduction method and storage medium |
| CN111862924A (en) * | 2019-04-25 | 2020-10-30 | 瑞昱半导体股份有限公司 | Audio adjusting method for active noise reduction and related audio adjusting device |
| CN115206278A (en) * | 2022-06-08 | 2022-10-18 | 荣耀终端有限公司 | Method and device for reducing noise of sound |
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