CN108495227A - Active denoising method, active noise reduction system and earphone - Google Patents

Abstract

The present invention proposes an active noise reduction method, an active noise reduction system, and earphones, and relates to the field of active noise reduction. The active noise reduction method includes: obtaining a sound transmission characteristic model of the secondary channel of the earphone; The preset filter is corrected to obtain a corrected filter; wherein, the filter is generated based on a sound transmission characteristic model of the earphone secondary channel. Through the combination of offline design and online correction, this method realizes the optimization of noise reduction performance based on the sound transmission characteristics of the ear canal of different earphone wearers. Compared with the existing adaptive active noise reduction method, this method has a small amount of online calculation and short calculation time, which effectively solves the problem of large phase deviation caused by long calculation time, and the method is simple and easy to implement in engineering.

Description

Active Noise Cancellation Method, Active Noise Cancellation System and Headphones

technical field

The invention relates to the field of active noise reduction, in particular to an active noise reduction method, an active noise reduction system and earphones.

Background technique

Active noise reduction earphones are a device that effectively reduces environmental noise. The secondary sound source emits a noise cancellation wave that is equal in amplitude and opposite in phase to the ambient noise to eliminate noise. The phase characteristics of the noise cancellation wave will directly affect the noise reduction. Effect. In the narrow enclosed space formed by the earphone, pinna, and ear canal, individual differences in human ears will cause phase deviations. For a filter with fixed parameters designed based on the sound transmission characteristics of the noise in the enclosed space of the earphone, the above deviation will lead to a decrease in the consistency of the noise reduction performance on the one hand; Noise enhancement occurs due to noise waves.

In order to overcome the above-mentioned problems caused by the filter with fixed parameters, the prior art uses an adaptive filter to achieve an optimal noise reduction effect. Patented a method and system for active noise reduction (201510629511.4), which proposes an adaptive noise reduction method that enables active noise reduction to adapt to the physical response from the speaker to the observation point. For active noise reduction headphones, the physical response from the speaker to the feedback microphone can reflect the propagation characteristics of the noise in the headphones. In theory, patent 201510629511.4 can overcome the above-mentioned phase deviation problem, but since the adaptive noise reduction method is an online design method, A digital filter is required, and the huge amount of calculation will lead to a long time delay. In addition to the circuit delay of the digital filter itself, the phase deviation of the filter caused by the total time delay cannot be ignored.

Contents of the invention

In view of the above problems, the present invention proposes an active noise reduction method, an active noise reduction system and earphones to solve the problem of deteriorating noise reduction performance due to phase difference caused by long online calculation time.

In the first aspect, the embodiment of the present application provides an active noise reduction method, including:

Obtain the sound transmission characteristic model of the earphone secondary channel;

According to the sound transmission characteristics of the user's ear canal, the pre-set filter is modified to obtain a modified filter; wherein, the filter is generated based on the sound transmission characteristic model of the earphone secondary channel.

Optionally, said acquiring the earphone secondary channel sound transmission characteristic model G0 includes:

Based on the input data and output data of the secondary channel of the earphone, a sound transmission characteristic model of the secondary channel of the earphone is established.

Optionally, the filter includes any one of a feedforward filter, a feedback filter, and a composite feedforward and feedback filter.

Optionally, according to the sound transmission characteristics of the user's ear canal, the pre-set filter is modified to obtain a modified filter, including:

Determine the user's ear canal sound transmission characteristic model and ear canal sound transmission characteristic model library;

Using a similarity algorithm to calculate the similarity between the user's ear canal sound transmission characteristic model and any model in the ear canal sound transmission characteristic model library, and obtain the model in the ear canal sound transmission characteristic model library with the highest similarity ;

Based on the model, a modified filter is determined, and based on the filter and the modified filter, a modified filter is obtained.

Optionally, the similarity algorithm includes:

performing alignment processing on the frequency response curve corresponding to the user's ear canal sound transmission characteristic model and a curve in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library, to obtain the aligned curve;

calculating the similarity between the aligned curve and the curve in the frequency response curve family.

Optionally, the aligning the frequency response curve corresponding to the ear canal sound transmission characteristic model of the user with a curve in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library includes:

Determine the parameter k so that ||li-k*l|| ₂ is the smallest;

Among them, in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library {G _i '}, the curves processed by the similarity algorithm, l is the frequency response curve corresponding to the ear canal sound transmission characteristic model, and k is a real number.

Optionally, the similarity is Sn=||li-k*l|| ₂ ;

Among them, Sn is the similarity between the aligned curve l' and the curve li in the frequency response curve family.

Optionally, the determining a modified filter based on the model, and obtaining a modified filter based on the filter and the modified filter include:

Establishing a corresponding correction filter library for the ear canal sound transmission characteristic model library;

According to the corresponding model of the ear canal sound transmission characteristic model of the user in the ear canal sound transmission characteristic model library, a corresponding modification filter in the modification filter library is determined.

In the second aspect, the embodiment of the present application provides an active noise reduction system, including: a noise measurement device, a sound transmission device, a filter circuit, and a correction circuit;

The noise measurement device includes: a first input terminal, a first output terminal and a second output terminal;

The filter circuit includes: a first input terminal, a second input terminal and a first output terminal;

The sound transmission device includes: a first input terminal, a second input terminal, a first output terminal and a second output terminal;

The correction circuit includes: a first input terminal, a second input terminal, a first output terminal and a second output terminal;

The first output end of the noise measurement device is electrically connected to the first input end of the filter circuit, and the second output end of the noise measurement device is electrically connected to the first input end of the correction circuit;

The first input end of the filter circuit is electrically connected to the first output end of the noise measuring device, and the second input end of the filter circuit is electrically connected to the first output end of the correction circuit , the first output end of the filter circuit is electrically connected to the first input end of the sound transmission device;

The first input end of the sound transmission device is electrically connected to the first output end of the filter circuit, the second input end of the sound transmission device is electrically connected to the second output end of the correction circuit, The second output end of the sound transmission device is electrically connected to the second input end of the correction circuit;

The first input end of the correction circuit is electrically connected to the second output end of the noise measuring device, the second input end of the correction circuit is electrically connected to the second output end of the sound transmission device, The first output end of the correction circuit is electrically connected to the second input end of the filter circuit, and the second output end of the correction circuit is electrically connected to the second input end of the sound transmission device ;

The noise measurement device is used to detect noise signals;

The filter circuit is used to generate a noise cancellation signal;

The acoustic transmission device is used to convert electrical signals into acoustic signals;

The correction circuit is used to modify the filter of the filter circuit.

Optionally, the filter circuit includes an analog-to-digital conversion circuit, a filter, and a digital-to-analog conversion circuit, and the filter is electrically connected to the analog-to-digital conversion circuit and the digital-to-analog conversion circuit, respectively.

Optionally, the filter is any one of a feedforward filter, a feedback filter, and a feedforward and feedback composite filter.

Optionally, the correction circuit includes a trigger circuit, a storage circuit, a calculation circuit and an analysis circuit;

The trigger circuit includes a first output terminal, a second output terminal and a third output terminal;

The calculation circuit includes a first input terminal, a second input terminal, a third input terminal and a first output terminal;

The analysis circuit includes a first input terminal, a second input terminal and a first output terminal;

The first output end of the trigger circuit is connected to the second input end of the sound transmission device, the second output end of the trigger circuit is electrically connected to the input end of the storage circuit, and the trigger circuit The third output end is electrically connected to the first input end of the calculation circuit;

The first input end of the calculation circuit is electrically connected to the third output end of the trigger circuit, the second input end of the calculation circuit is electrically connected to the second output end of the noise measurement device, and the The third input end of the calculation circuit is electrically connected to the second output end of the sound transmission device;

The input end of the storage circuit is electrically connected to the second output end of the trigger circuit, and the output end of the storage circuit is electrically connected to the first input end of the analysis circuit;

The first input end of the analysis circuit is electrically connected to the output end of the storage circuit, the second input end of the analysis circuit is electrically connected to the first output end of the calculation circuit, and the analysis circuit The first output end of the filter circuit is electrically connected with the second input end of the filter circuit;

The trigger circuit is used to trigger the sound transmission device to emit an acoustic signal, and simultaneously trigger the calculation circuit and the storage circuit;

The calculation circuit is used to calculate the current user's ear canal sound transmission characteristics;

The storage circuit is used to store various ear canal sound transmission characteristic data and corresponding filter parameter data;

The analysis circuit is used to analyze the filter parameters suitable for the current user's ear canal sound transmission characteristics.

In a third aspect, an embodiment of the present application provides an earphone, including a trigger switch for triggering a trigger circuit.

The present invention proposes an active noise reduction method, an active noise reduction system, and earphones, and relates to the field of active noise reduction. The active noise reduction method includes: obtaining a sound transmission characteristic model of the secondary channel of the earphone; The preset filter is corrected to obtain a corrected filter; wherein, the filter is generated based on a sound transmission characteristic model of the earphone secondary channel. Through the combination of offline design and online correction, this method realizes the optimization of noise reduction performance based on the sound transmission characteristics of the ear canal of different earphone wearers. Compared with the existing adaptive active noise reduction method, this method has a small amount of online calculation and short calculation time, which effectively solves the problem of large phase deviation caused by long calculation time, and the method is simple and easy to implement in engineering.

Description of drawings

In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings that need to be used in the description of the specific embodiments or the prior art. Obviously, the accompanying drawings in the following description The drawings show some implementations of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

FIG. 1 shows a flowchart of an active noise reduction method provided by Embodiment 1 of the present invention;

FIG. 2 shows a schematic structural diagram of an active noise reduction system provided by Embodiment 2 of the present invention;

FIG. 3 shows a schematic structural diagram of a filter circuit provided by Embodiment 2 of the present invention;

FIG. 4 shows a schematic structural diagram of a correction circuit provided by Embodiment 2 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only some of the embodiments of the present invention, but not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "first", "second" and "third" are used for description purposes only, and should not be understood as indicating or implying relative importance. Unless otherwise clearly specified and limited, the terms "connected" and "connected" should be interpreted in a broad sense, for example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection. Connection; it can be a direct connection or an indirect connection through an intermediary, and it can be an internal connection between two elements. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present invention in specific situations.

Example 1

The flow chart of the active noise reduction method shown in Figure 1, the present invention proposes an active noise reduction method, including the following steps:

S10: Obtain the sound transmission characteristic model G0 of the secondary channel of the earphone;

S20: According to the sound transmission characteristic G0 of the user's ear canal, modify the preset filter H0 to obtain the corrected filter H1; wherein, the filter H0 is based on the sound transmission characteristic model of the earphone secondary channel Generated by G0.

The above-mentioned active noise reduction method and the method of obtaining the sound transmission characteristic model of the earphone secondary channel have been introduced in detail in the prior art, and will not be described too much here; step S10 and step S20 are offline establishment and offline design, step S20 is implemented online, which is an active noise reduction method combining offline and online. Compared with all online adaptive design methods, the calculation amount is significantly reduced, the calculation time is shortened, and the phase deviation is also effectively reduced.

The above step S10 includes: based on the input data and output data of the secondary channel, establishing a sound transmission characteristic model of the secondary channel of the earphone, and expressing it with a transfer function formula G0. Preferably, the input time-domain data and output time-domain data of the secondary channel are measured and obtained respectively, and the sound transmission characteristic model of the secondary channel of the earphone is established, and the transfer function is expressed by G0, G0(s)=B ₁ (s)/A ₁ (s), where B ₁ (s) represents the Laplace transform of the output data, which is the numerator of the algebraic formula G0(s), and A ₁ (s) represents the Laplace transform of the input data, which is the algebraic formula G0(s ) denominator polynomial, s represents the differential operator, and the order and parameters of B ₁ (s) and A ₁ (s) are determined by the method of least squares.

In the above step S20, the filter includes any one of a feedforward filter, a feedback filter, and a composite feedforward and feedback filter. For the feedforward filter H0 _FF , it can be determined by solving the following problem: H0 _FF that makes ‖G1-G0×H0 _FF ‖ ₂ the smallest. Among them, G1 is the transfer function expression of the sound transmission characteristic model of the main channel, which is obtained by measuring the input time domain data and output time domain data of the main channel, and using the method of least squares. For the feedback filter H0 _FB , it can be determined by solving the following problem: the feedback filter H0 _FB that minimizes ∥1/(1-G0×H0 _FB )∥ ₂ . For feed-forward and feedback composite filters, the feed-forward filter and the feedback filter can be obtained respectively, and the solution method is the same as the above-mentioned separate feed-forward filter and feedback filter.

The above step S20 includes the following steps S201 to S203:

S201: Determine the user's ear canal sound transmission characteristic model G' and the ear canal sound transmission characteristic model library {G _i '}, where i=1, 2...n is a positive integer greater than or equal to 1, and is the ear canal of n users A collection of sound transmission characteristic models;

S202: Use a similarity algorithm to calculate the similarity between the user's ear canal sound transmission characteristic model G' and any model in the ear canal sound transmission characteristic model library {G _i '}, and obtain the ear canal with the highest similarity. The model G _i ' in the channel sound transmission characteristic model library {G _i '};

S203: Based on the acquired model Gi', determine a modified filter H', and obtain a modified filter H1=H0×H' based on the filter H0 and the modified filter H'.

In the above step S201, the ear canal sound transmission characteristic model G' of the ear canal user is determined online, and the ear canal sound transmission characteristic model library {Gi'} is designed offline. The online determination and offline design have been detailed in the prior art. Introduction, no more explanation here.

Preferably, based on the headphones being worn by the current user, a secondary channel sound transmission characteristic model G1(s) based on the user's ear canal sound transmission characteristics is established, and based on the above-mentioned earphone secondary channel sound transmission characteristic model G0(s), Then the user's ear canal sound transmission characteristic model G' can be expressed as G'=G1(s)/G0(s); for the ear canal sound transmission characteristic model library {Gi'}, earphones wearing Or, obtain the secondary channel sound transmission characteristic model G _i (s) of each earphone wearer, based on the earphone secondary channel sound transmission characteristic model G0(s), the ear canal sound transmission characteristic model library {Gi'} can be obtained ={G _i (s)/G0 (s)}. Among them, s represents the differential operator.

In the above step S202, based on the user's ear canal sound transmission characteristic model G' and the ear canal sound transmission characteristic model library {Gi'}, use the similarity algorithm to calculate the frequency response curve corresponding to the user's ear canal sound transmission characteristic model G' The similarity between l and any frequency response curve in the frequency response curve family {li'} corresponding to the ear canal sound transmission characteristic model library {Gi'}, to obtain the ear canal sound transmission characteristic model library {Gi'} with the highest similarity The frequency response curve in Gi'} corresponds to the model Gi'.

The similarity algorithm in the above step S202 includes the following steps S2021 and S2022:

S2021: Align the frequency response curve l corresponding to the user's ear canal sound transmission characteristic model G' with a curve li in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library {Gi'}, to obtain the alignment After the curve l';

S2022: Calculate the similarity between the aligned curve l' and the curve li in the frequency response curve family.

Wherein, the alignment includes determining a parameter k such that ||li-k*l|| ₂ is the smallest.

Among them, li is the curve of the frequency response curve corresponding to the ear canal sound transmission characteristic model library {G _i '}, which is processed by the similarity algorithm, l is the frequency response curve corresponding to the ear canal sound transmission characteristic model G', and k is real number.

The above similarity is Sn=||li-k*l|| ₂ .

Among them, Sn is the similarity between the aligned curve l' and the curve li in the frequency response curve family.

After aligning the current user's ear canal sound transmission characteristic frequency response curve l with all frequency response curves li in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library {Gi'}, calculate the aligned curve l' and The similarity of the curve li in the frequency response curve family can be seen from the formula of the similarity Sn, the smaller the Sn is, the higher the similarity is. That is, the frequency response curve corresponding to the smallest value is selected, and the ear canal sound transmission characteristic model corresponding to the frequency response curve is the ear canal sound transmission characteristic model of the current user of the earphone. The more models there are in the model library {Gi’}, the more accurate the ear canal sound transmission characteristic model of the current earphone user determined according to them is, but the amount of calculation will also increase, and the delay of the noise reduction system will also increase. The values of the models in the model library need to be determined according to the actual situation and the difficulty and effect of engineering practice.

The above step S203 includes the following steps S2031 and S2032:

S2031: For the ear canal sound transmission characteristic model library {Gi'}, establish a corresponding correction filter library {Hi'}, and each ear canal sound transmission characteristic model corresponds to a correction filter;

S2032: According to the user's ear canal sound transmission characteristic model G' corresponding to the model Gi' in the ear canal sound transmission characteristic model library {Gi'}, determine the corresponding correction filter library {Hi'} The modified filter H'.

In the above step S2031, the filter type is consistent with the filter type in step S20. Design a filter for each model Gi' in the model library {Gi'}. For the feedforward filter Hi' _FF , it can be determined by solving the following problem: that is, the Hi' _FF that makes ‖G1-Gi'×H0 _FF ‖ ₂ the smallest. Among them, G1 is the transfer function expression of the sound transmission characteristic model of the main channel, which is obtained by measuring the input time domain data and output time domain data of the main channel, and using the method of least squares. For the feedback filter Hi' _FB , it can be determined by solving the following problem: that is, Hi' _FB that makes ‖1/(1-Gi'×Hi' _FB )‖ ₂ the smallest. For feed-forward and feedback composite filters, the feed-forward filter and the feedback filter can be obtained respectively, and the solution method is the same as the above-mentioned separate feed-forward filter and feedback filter.

In step S2032, there is a one-to-one correspondence between the model Gi' in the model library {Gi'} and the filter Hi' in the filter library {Hi'}, once the model Gi' in the model library {Gi'} is determined, Then the filter Hi' corresponding to the model Gi' is also determined. The correction filter is H'=Hi'/H0. Through the modified filter H', the original filter H0 is modified to Hi', which realizes online adaptation of different filters based on the sound transmission characteristics of different users' ear canals.

Example 2

The structure diagram of the active noise reduction system shown in Figure 2, the present invention proposes an active noise reduction system, which can be used to implement the active noise reduction method proposed in Embodiment 1, including a noise measurement device 100, a filter circuit 200, and a sound transmission device 300. Correction circuit 400.

The noise measuring device 100 includes a first input terminal, a first output terminal and a second output terminal.

The filtering circuit 200 includes a first input terminal, a second input terminal and a first output terminal.

The sound transmission device 300 includes a first input terminal, a second input terminal, a first output terminal and a second output terminal.

The modification circuit 400 includes a first input terminal, a second input terminal, a first output terminal and a second output terminal.

The first output end of the noise measurement device 100 is electrically connected to the first input end of the filter circuit 200 , and the second output end of the noise measurement device 100 is electrically connected to the first input end of the correction circuit 400 .

The first input end of the filter circuit 200 is electrically connected to the first output end of the noise measurement device 100, the second input end of the filter circuit 200 is electrically connected to the first output end of the correction circuit 400, and the first output end of the filter circuit 200 The terminal is electrically connected to the first input terminal of the sound transmission device 300 .

The first input end of the sound transmission device 300 is electrically connected to the first output end of the filter circuit 200, the second input end of the sound transmission device 300 is electrically connected to the second output end of the correction circuit 400, and the second output end of the sound transmission device 300 The two output terminals are electrically connected to the second input terminal of the correction circuit 400 .

The first input end of the correction circuit 400 is electrically connected to the second output end of the noise measurement device 100, the second input end of the correction circuit 400 is electrically connected to the second output end of the sound transmission device 300, and the first input end of the correction circuit 400 The output end is electrically connected to the second input end of the filter circuit 200 , and the second output end of the correction circuit 400 is electrically connected to the second input end of the sound transmission device 300 .

The noise measurement device 100 is used to detect noise signals.

The filtering circuit 200 is used to generate a noise-canceling signal.

The acoustic transmission device 300 is used to convert electrical signals into acoustic signals;

The modification circuit 400 is used for modifying the filter of the filter circuit.

In one embodiment, the above-mentioned active noise reduction system includes a correction mode and a noise reduction mode; the correction mode is to correct the filter at the initial stage of earphone wearing; the noise reduction mode is to perform noise reduction processing on the environmental noise after the filter is corrected. For the correction mode, the correction circuit 400 sends a trigger signal, and the trigger signal triggers the sound transmission device 300 to emit an acoustic signal, and the noise detection device 100 detects the above-mentioned acoustic signal, and converts the acoustic signal into an electrical signal, and the electric signal is connected with the sound transmission device 300. The input electrical signals are all transmitted to the correction circuit, and the correction circuit calculates and outputs the correction filter, and uses the correction filter to modify the current filter. For the noise reduction mode, the noise detection device 100 transmits the detected noise signal to the filter circuit 200, and outputs a noise reduction signal after being processed by the filter circuit 200. After broadcasting, get the denoised wave.

In one embodiment, as shown in FIG. 3 , the filter circuit 200 includes an analog-to-digital conversion circuit 210 , a filter 220 and a digital-to-analog conversion circuit 230 . The filter 220 is electrically connected to the analog-to-digital conversion circuit 210 and the digital-to-analog conversion circuit 230 respectively. The filter circuit 200 is a digital filter circuit, so that filter parameters can be modified online.

In one embodiment, referring to FIG. 3 , the above-mentioned filter is any one of the feedforward filter 222 , the feedback filter 221 , and the composite feedforward and feedback filter. Feedforward filter and feedback filter can be designed separately.

In one embodiment, the structural diagram of the correction circuit shown in FIG. 4 includes a trigger circuit 410 , a storage circuit 420 , a calculation circuit 430 and an analysis circuit 440 .

The trigger circuit 410 includes a first output terminal in1 , a second output terminal in2 and a third output terminal in3 .

The calculation circuit 430 includes a first input terminal in1 , a second input terminal in2 , a third input terminal in3 and a first output terminal out1 .

The analysis circuit 440 includes a first input terminal in1 , a second input terminal in2 and a first output terminal out1 .

The first output terminal out1 of the trigger circuit 410 is electrically connected to the second input terminal in2 of the sound transmission device 300, the second output terminal out2 of the trigger circuit 410 is electrically connected to the input terminal of the storage circuit 420, and the third output terminal of the trigger circuit 410 The output terminal out3 is electrically connected to the first input terminal in1 of the calculation circuit 430 .

The first input terminal in1 of the calculation circuit 430 is electrically connected to the third output terminal out3 of the trigger circuit 410, the second input terminal in2 of the calculation circuit 430 is electrically connected to the second output terminal out2 of the noise measurement device 100, and the calculation circuit 430 The third input terminal in3 is electrically connected to the second output terminal out2 of the sound transmission device 300 .

The input end of the storage circuit 420 is electrically connected to the second output end out2 of the trigger circuit 410 , and the output end of the storage circuit 420 is electrically connected to the first input end in1 of the analysis circuit 440 .

The first input terminal in1 of the analysis circuit 440 is electrically connected to the output terminal of the storage circuit 420, the second input terminal in2 of the analysis circuit 440 is electrically connected to the first output terminal out1 of the calculation circuit 430, and the first output terminal of the analysis circuit 440 It is electrically connected with the second input terminal in2 of the filter circuit 200 .

The trigger circuit 410 is used for triggering the sound transmission device 300 to emit an acoustic signal, and simultaneously triggering the calculation circuit 430 and the storage circuit 420 . The trigger circuit 410 triggers the sound transmitting device 300 to receive an electrical signal, converts the electrical signal into an acoustic signal and sends it out; at the same time triggers the calculation circuit 430 and the storage circuit 420, and after the calculation circuit 430 and the storage circuit 420 are powered on, they are started and ready to work.

The calculation circuit 430 is used to calculate the sound transmission characteristics of the current user's ear canal. The calculation circuit 430 receives the input electrical signal of the acoustic transmission device 300, and the electrical signal of the acoustic signal emitted by the acoustic transmission device 300 detected by the noise detection device 100, and according to the input electrical signal of the above-mentioned acoustic transmission device and the electrical signal detected by the noise monitoring device , calculate and output the current user's ear canal sound transmission characteristic model data to the analysis circuit.

The storage circuit 420 is used for storing various kinds of acoustic transmission characteristic data of the ear canal and corresponding filtering parameters. After the storage circuit 420 is triggered, the stored data is transmitted to the analysis circuit 440 . Preferably, in order to save the storage space of the analysis circuit 440 , the storage circuit 420 may send data to the analysis circuit 440 in groups.

The analysis circuit 440 is used to analyze the modified filter parameters suitable for the current user's ear canal sound transmission characteristics. According to the current user's ear canal sound transmission characteristic model data from the calculation circuit 430 and the model library and filter library data from the storage circuit 420 , corrected filter parameters can be obtained, and the filter parameters are output to the filter circuit 200 . Preferably, the analysis circuit 440 analyzes the calculation results based on the current user's ear canal sound transmission characteristic model data and the current set of model data and corresponding filter data from the storage circuit 420 and records the analysis results, when the storage circuit 420 All the grouped data in have been output to the analysis circuit 440 , and the corrected filter parameters corresponding to the optimal result can be selected from all the analysis results as the output of the analysis circuit 440 .

The invention proposes an active noise reduction method, an active noise reduction system, and an earphone. The method realizes the optimization of noise reduction performance based on the sound transmission characteristics of ear canals of different earphone wearers through the combination of offline design and online correction. Compared with the existing adaptive active noise reduction method, this method has a small amount of online calculation and short calculation time, which effectively solves the problem of large phase deviation caused by long calculation time, and the method is simple and easy to implement in engineering.

Example 3

The present invention also proposes an earphone, which includes the active noise reduction system in Embodiment 2, and also includes a trigger switch for triggering the trigger circuit. The starting switch can be turned on in a manual mode or an automatic mode. When it is in manual mode, the user manually turns on the trigger switch, trigger circuit 410 starts to work, and starts the correction mode; when it is in automatic mode, the earphone detects that a wearer is wearing the earphone and wears it, then automatically turns on the trigger switch, and triggers the circuit 410 starts to work and starts the correction mode. The earphone with the active noise reduction system proposed in Embodiment 2 can modify the filter parameters online according to the user's ear canal sound transmission characteristics, and has good adaptability to the user's ear canal sound transmission characteristics, and is better than using an adaptive algorithm The active noise reduction earphones have a small calculation amount and a very short calculation time, which can ensure good noise reduction performance.

Apparently, those skilled in the art can clearly understand that each step of the above-mentioned design method can be implemented by a general-purpose computing device, and they can be concentrated on a single computing device, or distributed on a network composed of multiple computing devices , alternatively, they can be implemented with executable program codes of the computing device, thus, they can be stored in the storage device and executed by the computing device, or they can be made into individual integrated circuit modules respectively, or the Multiple modules or steps are implemented as a single integrated circuit module. As such, the present invention is not limited to any specific combination of hardware and software.

Relative steps, numerical expressions and numerical values of components and steps set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise.

The implementation principles and technical effects of the device provided by the embodiment of the present invention are the same as those of the foregoing method embodiment. For brief description, for the parts not mentioned in the device embodiment, reference may be made to the corresponding content in the foregoing method embodiment.

In all examples shown and described herein, any specific values should be construed as merely exemplary and not limiting, and thus other examples of the exemplary embodiments may have different values.

It should be noted that like numerals and letters denote similar items in the following figures, therefore, once an item is defined in one figure, it does not require further definition and explanation in subsequent figures.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in a flowchart or block diagram may represent a module, program segment, or part of code that includes one or more Executable instructions. It should also be noted that, in some alternative implementations, the functions noted in the block may occur out of the order noted in the figures. For example, two blocks in succession may, in fact, be executed substantially concurrently, or they may sometimes be executed in the reverse order, depending upon the functionality involved. It should also be noted that each block of the block diagrams and/or flowchart illustrations, and combinations of blocks in the block diagrams and/or flowchart illustrations, can be implemented by a dedicated hardware-based system that performs the specified function or action , or may be implemented by a combination of dedicated hardware and computer instructions.

Claims (13)

1. The active noise reduction method is characterized in that, comprising: Obtain the sound transmission characteristic model of the earphone secondary channel; According to the sound transmission characteristics of the user's ear canal, the pre-set filter is modified to obtain a modified filter; wherein, the filter is generated based on the sound transmission characteristic model of the earphone secondary channel. 2. The active noise reduction method according to claim 1, wherein said obtaining the earphone secondary channel sound transmission characteristic model G0 comprises: Based on the input data and output data of the secondary channel of the earphone, a sound transmission characteristic model of the secondary channel of the earphone is established. 3. The active noise reduction method according to claim 1, wherein the filter comprises any one of a feedforward filter, a feedback filter, and a feedforward and feedback composite filter. 4. The active noise reduction method according to claim 1, wherein, according to the sound transmission characteristics of the user's ear canal, the pre-set filter is modified to obtain a modified filter, including: Determine the user's ear canal sound transmission characteristic model and ear canal sound transmission characteristic model library; Using a similarity algorithm to calculate the similarity between the user's ear canal sound transmission characteristic model and any model in the ear canal sound transmission characteristic model library, and obtain the model in the ear canal sound transmission characteristic model library with the highest similarity ; Based on the model, a modified filter is determined, and based on the filter and the modified filter, a modified filter is obtained. 5. The active noise reduction method according to claim 4, wherein the similarity algorithm comprises: performing alignment processing on the frequency response curve corresponding to the user's ear canal sound transmission characteristic model and a curve in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library, to obtain the aligned curve; calculating the similarity between the aligned curve and the curve in the frequency response curve family. 6. The active noise reduction method according to claim 5, wherein the frequency response curve corresponding to the user's ear canal sound transmission characteristic model and the frequency response corresponding to the ear canal sound transmission characteristic model library A curve in the curve family is aligned, including: Determine the parameter k so that ||li-k*l|| ₂ is the smallest; Among them, in the frequency response curve family corresponding to the ear canal sound transmission characteristic model library {G _i '}, the curves processed by the similarity algorithm, l is the frequency response curve corresponding to the ear canal sound transmission characteristic model, and k is a real number. 7. The active noise reduction method according to claim 6, wherein the similarity is Sn=||li-k*l|| ₂ ; Among them, Sn is the similarity between the aligned curve l' and the curve li in the frequency response curve family. 8. The active noise reduction method according to claim 4, wherein the determination of the modified filter based on the model, and obtaining the modified filter based on the filter and the modified filter include: Establishing a corresponding correction filter library for the ear canal sound transmission characteristic model library; According to the corresponding model of the ear canal sound transmission characteristic model of the user in the ear canal sound transmission characteristic model library, a corresponding modification filter in the modification filter library is determined. 9. The active noise reduction system is characterized in that it includes: a noise measurement device, a sound transmission device, a filter circuit, and a correction circuit; The noise measurement device includes: a first input terminal, a first output terminal and a second output terminal; The filter circuit includes: a first input terminal, a second input terminal and a first output terminal; The sound transmission device includes: a first input terminal, a second input terminal, a first output terminal and a second output terminal; The correction circuit includes: a first input terminal, a second input terminal, a first output terminal and a second output terminal; The first output end of the noise measurement device is electrically connected to the first input end of the filter circuit, and the second output end of the noise measurement device is electrically connected to the first input end of the correction circuit; The first input end of the filter circuit is electrically connected to the first output end of the noise measuring device, and the second input end of the filter circuit is electrically connected to the first output end of the correction circuit , the first output end of the filter circuit is electrically connected to the first input end of the sound transmission device; The first input end of the sound transmission device is electrically connected to the first output end of the filter circuit, the second input end of the sound transmission device is electrically connected to the second output end of the correction circuit, The second output end of the sound transmission device is electrically connected to the second input end of the correction circuit; The first input end of the correction circuit is electrically connected to the second output end of the noise measuring device, the second input end of the correction circuit is electrically connected to the second output end of the sound transmission device, The first output end of the correction circuit is electrically connected to the second input end of the filter circuit, and the second output end of the correction circuit is electrically connected to the second input end of the sound transmission device ; The noise measurement device is used to detect noise signals; The filter circuit is used to generate a noise cancellation signal; The acoustic transmission device is used to convert electrical signals into acoustic signals; The correction circuit is used to modify the filter of the filter circuit. 10. The active noise reduction system according to claim 9, wherein the filtering circuit comprises an analog-to-digital conversion circuit, a filter and a digital-to-analog conversion circuit, and the filter is connected to the analog-to-digital conversion circuit and the digital-to-analog conversion circuit respectively. The digital-to-analog conversion circuit is electrically connected. 11. The active noise reduction system according to claim 10, wherein the filter is any one of a feedforward filter, a feedback filter, and a composite feedforward and feedback filter. 12. The active noise reduction system according to claim 9, wherein the correction circuit comprises a trigger circuit, a storage circuit, a calculation circuit and an analysis circuit; The trigger circuit includes a first output terminal, a second output terminal and a third output terminal; The calculation circuit includes a first input terminal, a second input terminal, a third input terminal and a first output terminal; The analysis circuit includes a first input terminal, a second input terminal and a first output terminal; The first output end of the trigger circuit is connected to the second input end of the sound transmission device, the second output end of the trigger circuit is electrically connected to the input end of the storage circuit, and the trigger circuit The third output end is electrically connected to the first input end of the calculation circuit; The first input end of the calculation circuit is electrically connected to the third output end of the trigger circuit, the second input end of the calculation circuit is electrically connected to the second output end of the noise measurement device, and the The third input end of the calculation circuit is electrically connected to the second output end of the sound transmission device; The input end of the storage circuit is electrically connected to the second output end of the trigger circuit, and the output end of the storage circuit is electrically connected to the first input end of the analysis circuit; The first input end of the analysis circuit is electrically connected to the output end of the storage circuit, the second input end of the analysis circuit is electrically connected to the first output end of the calculation circuit, and the analysis circuit The first output end of the filter circuit is electrically connected with the second input end of the filter circuit; The trigger circuit is used to trigger the sound transmission device to emit an acoustic signal, and simultaneously trigger the calculation circuit and the storage circuit; The calculation circuit is used to calculate the current user's ear canal sound transmission characteristics; The storage circuit is used to store various ear canal sound transmission characteristic data and corresponding filter parameter data; The analysis circuit is used to analyze the filter parameters suitable for the current user's ear canal sound transmission characteristics. 13. The earphone, comprising the active noise reduction system according to any one of claims 9 to 12, characterized in that it comprises a trigger switch for triggering the trigger circuit.