Active noise reduction method, device, active noise reduction earphone and storage medium

Abstract

The embodiments of the present application provide an active noise reduction method, device, active noise reduction headphones and storage medium, which relate to the field of audio noise reduction. A processor applied to an active noise reduction headphone, the active noise reduction headphone includes a feedforward active noise reduction filter, the feedforward active noise reduction filter includes an IIR filter and a FIR filter; the active noise reduction method includes: obtaining a current first transfer function value; adjusting the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value; estimating the current overall frequency response required for the feedforward active noise reduction filter under the current first transfer function value; determining the target frequency response of the FIR filter based on the target configuration and the current overall frequency response; adjusting the FIR filter based on the target frequency response to use the adjusted FIR filter for noise reduction. This method helps to reduce the chip area required for the feedforward active noise reduction filter.

Description

Technical Field

[0001] The present application relates to the field of audio noise reduction, and specifically, provides an active noise reduction method, device, active noise reduction headphones and storage medium. Background Art

[0002] The active noise reduction headphones include a feedforward active noise reduction channel, which is used to implement feedforward active noise reduction.

[0003] The feedforward active noise reduction channel includes a feedforward active noise reduction filter, which includes a FIR (Finite Impulse Response, finite unit impulse response filter) filter and an IIR (Infinite Impulse Response, recursive filter) filter. Generally, the IIR filter is a fixed filter and the FIR filter is an adaptive filter. In the process of active noise reduction, the FIR filter adjusts its own filter coefficients to adjust the overall noise reduction capability of the feedforward active noise reduction filter.

[0004] If the feedforward active noise reduction filter is required to have a larger noise reduction capability adjustment range as a whole, the FIR filter needs to have a larger order to support the noise reduction capability adjustment range required by the feedforward active noise reduction filter. This method will cause the FIR filter to occupy a larger chip area, with higher power consumption and cost. Summary of the invention

[0005] In view of this, the present application aims to provide an active noise reduction method, device, active noise reduction headphones and storage medium, so as to reduce the chip area required for the feedforward active noise reduction filter and reduce its power consumption when the adjustment range of the noise reduction capability supported by the feedforward active noise reduction filter varies slightly.

[0006] First, an embodiment of the present application provides an active noise reduction method, which is applied to a processor of an active noise reduction headset, wherein the active noise reduction headset includes a feedforward active noise reduction filter, a feedback microphone and a speaker, and the feedforward active noise reduction filter includes an IIR filter and a FIR filter; the active noise reduction method includes: obtaining a current first transfer function value; the current first transfer function value is a value of a transfer function between the speaker and the feedback microphone; based on the current first transfer function value, adjusting the IIR filter to a target configuration corresponding to the current first transfer function value; estimating a current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value; determining a target frequency response of the FIR filter based on the target configuration and the current overall frequency response; and adjusting the FIR filter based on the target frequency response to perform noise reduction using the adjusted FIR filter.

[0007] IIR filter and FIR filter are two filters with different structures. Both of them can perform filtering and noise reduction, but the noise reduction effects of the two are different in different frequency bands. If the FIR filter needs to filter and adjust the audio signal in the low-frequency band to achieve better active noise reduction, it may be necessary to make the FIR filter have a higher order, thereby occupying a larger chip area and generating larger power consumption. In an embodiment of the present application, the IIR filter is configured as an adjustable filter. When the order of the IIR filter is relatively low, such as the 4th order, the 6th order, the 8th order, etc., the low-frequency band of the audio signal can still be greatly adjusted under appropriate configuration, so that the feedforward active noise reduction filter can achieve the preset noise reduction effect by adjusting the IIR filter. The chip area required and the power consumption generated by this method are often less than the chip area and the power consumption generated by the FIR filter when the same preset noise reduction effect is required. Therefore, by adjusting the configuration of the IIR filter, the noise reduction effect of the active noise reduction headphones can meet the preset noise reduction effect required for the current wearing method, and then the configuration of the FIR filter can be determined and adjusted through the frequency response. This method can reduce the overall chip area and overall power consumption of the feedforward active noise reduction filter and improve the feedforward active noise reduction performance.

[0008] After the user wears the active noise reduction headphones, the user wears the feedforward active noise reduction filter differently in different scenarios, and the noise reduction capabilities required by the feedforward active noise reduction filter are different. The noise reduction effect in the ear of the active noise reduction headphones is different under different wearing methods. The feedback microphone is used to collect the sound from the cavity formed between the ear and the headphone, and the sound played by the speaker is also in the cavity. Therefore, by calculating the value of the transfer function between the speaker and the feedback microphone (that is, the first transfer function value), the first transfer function value is used to characterize different scenarios or different wearing methods, and then determine the target configuration required for each scenario or each wearing method. In addition, the above method does not require the use of an adaptive iterative algorithm, which can effectively avoid the situation of unstable noise reduction caused by adaptive iteration, and effectively reduce the situation where the configuration adjustment time during active noise reduction is too long due to the convergence of adaptive iteration.

[0009] In one embodiment, the active noise reduction headset also includes a speaker and a feedback microphone; adjusting the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value includes: determining the target configuration from a preset first correspondence relationship based on the current first transfer function value, the first correspondence relationship including different configurations of the IIR filter corresponding to different first transfer function values; adjusting the IIR filter according to the target configuration.

[0010] Different first transfer function values ​​can be used to characterize different scenarios. In an embodiment of the present application, a first correspondence between the first transfer function value and different configurations of the IIR filter can be pre-configured. When in use, the required target configuration is determined based on the current first transfer function value and the first correspondence. This method helps to reduce the amount of calculation, improve the adjustment efficiency of the target configuration and reduce computing power consumption.

[0011] In one embodiment, different first function values ​​represent different wearing methods, and the first corresponding relationship is obtained by: simulating the prototype of the active noise reduction headset in different wearing methods respectively; for each wearing method: obtaining the first transfer function value corresponding to the wearing method; adjusting the configuration of the IIR filter until the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the wearing method, and recording the adjusted configuration of the IIR filter; establishing a corresponding relationship between the first transfer function values ​​corresponding to different wearing methods and the adjusted configuration of the IIR filter under different wearing methods, to obtain the first corresponding relationship.

[0012] In an embodiment of the present application, different wearing methods are simulated in advance, and the configuration of the IIR filter is adjusted under each wearing method, so that the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the current wearing method. As a result, the IIR filter configuration corresponding to each wearing method in the first corresponding relationship can have a better noise reduction effect.

[0013] In one embodiment, the noise reduction effect of the prototype matches the noise reduction effect required to be achieved by the wearing method, including: the noise reduction amount of the prototype reaches a preset value, or the noise reduction capability of the prototype reaches a maximum.

[0014] In the embodiment of the present application, when the noise reduction capability has not reached the maximum, the noise reduction effect is that the noise reduction amount reaches a preset value and is considered a match. This method helps to reduce the situation where the audio signal is inaccurate due to filter noise reduction.

[0015] In one embodiment, adjusting the FIR filter based on the target frequency response includes: converting the target frequency response into a target FIR filter coefficient group of the FIR filter; wherein the target FIR filter coefficient group includes: among a plurality of consecutive FIR filter coefficients, there are N1 FIR filter coefficients of 0 between every two non-zero FIR filter coefficients, and N1 is a positive integer; adjusting the FIR filter according to the target FIR filter coefficient group to obtain the adjusted FIR filter.

[0016] In the embodiment of the present application, since active noise reduction is generally used to reduce the noise of part of the ambient sound at the mid-low frequency, and the IIR filter can filter out the high-frequency noise components, even if some FIR filter coefficients are set to 0, that is, N1 FIR filter coefficients between every two non-zero FIR filter coefficients are set to 0, the filtering ability of the FIR filter to the high-frequency components of the audio is reduced, and the overall noise reduction effect of the feedforward active noise reduction filter is not greatly affected, and the user's normal listening is not affected. Making some FIR filter coefficients 0 can effectively reduce the amount of calculation of the FIR filter, and then a smaller FIR filter can be configured, reducing the area requirement of the FIR filter, and reducing the power consumption of the FIR filter. The method of reducing the order of the FIR filter can also reduce the amount of calculation, but the noise reduction performance of the FIR filter in the mid-low frequency is related to the order of the FIR filter. Compared with the method of reducing the order of the FIR filter, the method of making some FIR filter coefficients 0 can keep the FIR filter at a higher order and maintain better noise reduction performance in the mid-low frequency band. Therefore, this method can reduce the amount of calculation and power consumption without affecting the overall noise reduction performance of the feedforward active noise reduction filter.

[0017] In one embodiment, the IIR filter and the FIR filter operate at a first sampling rate, and the estimating the current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value includes: estimating the current overall frequency response corresponding to a second sampling rate under the current first transfer function value, and the second sampling rate is less than the first sampling rate; determining the target frequency response of the FIR filter based on the target configuration and the current overall frequency response includes: determining the target frequency response based on the current overall frequency response corresponding to the second sampling rate and the target configuration; converting the target frequency response into a target FIR filter coefficient group of the FIR filter includes: converting the target frequency response into multiple FIR filter coefficients; inserting N1 FIR filter coefficients with a value of 0 between each two adjacent FIR filter coefficients to obtain the target FIR filter coefficient group; wherein, N1=second sampling rate / first sampling rate-1.

[0018] In the embodiment of the present application, when calculating the current overall frequency response, the calculation is performed at the second sampling rate, and the second sampling rate is lower than the first sampling rate, which helps to reduce the power consumption and computing resources of estimating the current overall frequency response. By inserting N1 FIR filter coefficients with a value of 0 between each two adjacent FIR filter coefficients, more FIR filter coefficients can be used by the FIR filter, thereby reducing the amount of calculation when the FIR filter coefficients can be used normally, thereby reducing power consumption.

[0019] In one embodiment, the active noise reduction headset includes a feedforward microphone that estimates the current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value, including: obtaining an estimated error signal; obtaining a current second transfer function value, wherein the current second transfer function value is a value of the transfer function between the feedforward microphone and the feedback microphone; determining the current overall frequency response based on the error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship, wherein the second preset relationship includes a conversion relationship between the error signal, the first transfer function value, the second transfer function value, and the overall frequency response.

[0020] The error signal is related to the frequency response, the first transfer function value, and the second transfer function value of the feedforward active noise reduction filter. In the embodiment of the present application, the relationship between the four is recorded as the second preset relationship. When calculating the frequency response, the error signal to be achieved can be estimated, and then the first transfer function value and the second transfer function value are obtained, and then the current overall frequency response is calculated through the second preset relationship. Compared with the theoretical calculation method of the frequency response, this method helps to simplify the calculation process of the current overall frequency response, reduce power consumption, and improve calculation efficiency.

[0021] In one embodiment, the obtaining of the estimated error signal includes: minimizing the error signal; and determining the overall frequency response based on the error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship includes: determining the current overall frequency response based on the minimized error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship.

[0022] Ideally, when the noise reduction effect is optimal, the error signal should reach the minimum value of 0. Therefore, in the embodiment of the present application, the current overall frequency response can be estimated when the error signal is minimized, so as to obtain the current overall frequency response corresponding to the feedforward active filter with better noise reduction effect as much as possible. Based on the current overall frequency response, the target frequency response of the FIR filter is calculated in turn, and the FIR filter is configured with the target frequency response, so that the feedforward active filter can have an excellent noise reduction effect.

[0023] In a second aspect, an embodiment of the present application provides an active noise reduction device, which is applied to a processor of an active noise reduction headset, wherein the active noise reduction headset includes a feedforward active noise reduction filter, a feedback microphone and a speaker, and the feedforward active noise reduction filter includes an IIR filter and a FIR filter; the active noise reduction device includes: a first configuration module, which obtains a current first transfer function value, and adjusts the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value; wherein the current first transfer function value is the value of the transfer function between the speaker and the feedback microphone; a first calculation module, which is used to estimate the current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value; a second calculation module, which is used to determine the target frequency response of the FIR filter based on the target configuration and the current overall frequency response; and a second configuration module, which is used to adjust the FIR filter based on the target frequency response to use the adjusted FIR filter for noise reduction.

[0024] In a third aspect, an embodiment of the present application provides an active noise reduction headset, comprising: a feedforward active noise reduction channel, comprising a feedforward microphone and a feedforward active noise reduction filter, the feedforward microphone being connected to the feedforward active noise reduction filter; the IIR filter and the FIR filter being configured to allow adjustment of the configuration; a feedback active noise reduction channel, comprising a feedback microphone and a feedback active noise reduction filter, the feedback microphone and a feedback active noise reduction filter speaker being connected to the feedback active noise reduction filter and the feedforward active noise reduction filter; a processor, respectively connected to the feedforward active noise reduction channel and the feedback active noise reduction channel, for executing the active noise reduction method as described in any one of the first aspects.

[0025] In a fourth aspect, an embodiment of the present application provides a readable storage medium, wherein the readable storage medium stores instructions, and the instructions can be executed by one or more processors to implement the active noise reduction method as described in any one of the first aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0027] Figure 1 A schematic diagram of the structure of an active noise reduction headset provided in one embodiment of the present application;

[0028] Figure 2A schematic diagram of an active noise reduction channel provided in an embodiment of the present application;

[0029] Figure 3 A schematic diagram of a feedforward active noise reduction filter provided in an embodiment of the present application;

[0030] Figure 4 A flowchart of an active noise reduction method provided in one embodiment of the present application;

[0031] Figure 5 A schematic diagram of an active noise reduction device provided in one embodiment of the present application.

[0032] Icon: active noise reduction headphones 100; processor 110; feedforward active noise reduction channel 120; feedforward microphone 121; feedforward active noise reduction filter 122; FIR filter 1221; IIR filter 12221222; feedback active noise reduction channel 130; feedback microphone 131; feedback active noise reduction filter 132; speaker 140; analog gain unit 151; analog-to-digital converter 152; low-pass and downsampling filter 153; limiter 154; audio echo module 155; digital-to-analog converter 156; active noise reduction device 300; first configuration module 310; first calculation module 320; second calculation module 330; second configuration module 340. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solution and advantages of the embodiments of the present application more clear, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present application and are not used to limit the present application.

[0034] First, an embodiment of the present application provides an active noise reduction headset, which can be an in-ear headset, a semi-in-ear headset, an open headset, or a head-mounted headset, without limitation herein.

[0035] See also Figure 1 , Figure 1 The schematic diagram of an active noise reduction headset provided by an embodiment of the present application is as follows. The active noise reduction headset 100 comprises: a processor 110 , a feedforward active noise reduction channel 120 , a feedback active noise reduction channel 130 and a speaker 140 .

[0036] The processor 110 is used to execute the active noise reduction method provided in the embodiment of the present application. The active noise reduction method will be expanded later and will not be described in detail here.

[0037] The feedforward active noise reduction channel 120 and the feedback noise reduction channel of the active noise reduction headset 100 are collectively referred to as active noise reduction channels. The feedforward active noise reduction channel 120 and the feedback active noise reduction channel 130 are both connected to the processor 110, and the feedforward active noise reduction channel 120 and the feedback active noise reduction channel 130 are also connected to the speaker 140. The speaker 140 is used to play the audio signal after the feedforward active noise reduction channel 120 and the feedback active noise reduction channel 130 are subjected to noise reduction.

[0038] See also Figure 2 , Figure 2 A schematic diagram of an active noise reduction channel provided in an embodiment of the present application.

[0039] The feedforward active noise reduction channel includes a feedforward microphone 121, an analog gain unit 151, an analog-to-digital converter 152, a low-pass and down-sampling filter 153, and a feedforward active noise reduction filter 122 connected in sequence. The audio signal collected by the feedforward microphone 121 passes through the feedforward microphone 121, the analog gain unit 151, the analog-to-digital converter 152, the low-pass and down-sampling filter 153, and the feedforward active noise reduction filter 122 in sequence, and is output to the digital-to-analog converter 156, which is converted into an analog signal by the digital-to-analog converter 156 and then output to the speaker 140 for playback. Among them, the microphone of the feedforward active noise reduction channel is placed on the outside of the earphone for collecting sounds outside the ear, so it can also be called an external ear microphone. The feedforward microphone 121 can be composed of multiple microphones, and the audio signal collected by the feedforward microphone 121 can be beamformed first, and then passed through the feedforward active noise reduction filter 122 to reduce noise. In other embodiments, the feedforward microphone 121 can also be a separately arranged microphone, which is not limited here.

[0040] See also Figure 3 , Figure 3 A schematic diagram of a feedforward active noise reduction filter provided in an embodiment of the present application.

[0041] In an embodiment of the present application, the feedforward active noise reduction filter 122 includes a FIR filter 1221 and an IIR filter 1222. The IIR filter 1222 can be connected in parallel with the FIR filter 1221. Figure 3 As shown in IIR filter No. 1 in FIG. 1 , IIR filter 1222 can be connected in series with FIR filter 1221, such as Figure 3 The number of IIR filters can be 1 or 2, and the feedforward active noise reduction filter can only include Figure 3 One of the IIR filter No. 1 and the IIR filter No. 2 shown may also include two IIR filters at the same time.

[0042] In an embodiment of the present application, the FIR filter 1221 and the IIR filter 1222 are both configurable filters, and the configurations of the FIR filter 1221 and the IIR filter 1222 can be modified, such as changing the filter coefficients, to adjust the noise reduction capabilities of the FIR filter 1221 and the IIR filter 1222.

[0043] like Figure 2 As shown, the feedback active noise reduction channel 130 includes a feedback microphone 131, an analog gain unit 151, an analog-to-digital converter 152, a low-pass and down-sampling filter 153, and a feedback active noise reduction filter 132 which are connected in sequence.

[0044] The feedback microphone 131 of the feedback active noise reduction channel 130 is placed inside the earphone, close to the ear canal when worn, and is used to collect the sound in the ear to perform feedback noise reduction based on the sound collected in the ear. Therefore, the feedback microphone 131 can also be called an in-ear microphone. In some embodiments, the in-ear microphone can also be a separately set microphone or a microphone array.

[0045] In addition, the active noise reduction headset 100 may also include an audio echo module 155. In the active noise reduction headset 100, when playing audio, the audio to be played can be output to the digital-to-analog converter 156 for conversion and played by the speaker 140. On the other hand, when the feedback active noise reduction channel 130 is turned on, the audio signal to be played passes through the audio echo module 155 to offset the audio component to be played in the feedback active noise reduction channel 130, so that the sound collected in the feedback active noise reduction channel 130 is not affected by the audio to be played. Specifically, the audio signal to be played is added or subtracted from the output of the audio echo module 155 and the low-pass and down-sampling filter 153 module in the feedback active noise reduction channel 130. After eliminating the influence of the audio to be played on the feedback active noise reduction channel 130, the remaining environmental noise is sent to the feedback active noise reduction filter 132 as the input of the digital-to-analog converter 156. Among them, the echo filter in the audio echo module can be an adaptive or fixed filter, an IIR structure, an FIR structure, or a filter structure mixed with IIR and FIR.

[0046] In some embodiments, when the feedback active noise reduction channel 130 is turned on, the output of the feedforward active noise reduction channel can also pass through the audio echo module 155 to offset the component of the feedforward audio signal in the feedback active noise reduction channel 130, so that the sound collected in the feedback active noise reduction channel 130 is not affected by the feedforward audio signal. In some scenarios, the output of the feedforward active noise reduction channel is added to the played audio as the input of the audio echo module 155.

[0047] The analog gain unit 151, analog-to-digital converter 152, and low-pass and down-sampling filter 153 of the feedback active noise reduction channel 130 and the feedforward active noise reduction channel respectively play the same role, and their structures can be the same or different, which is not limited here.

[0048] In some embodiments, the feedback active noise reduction channel 130 may also be provided with a limiter 154, and the limiter 154 is connected between the feedback active noise reduction filter 132 and the digital-to-analog converter 156. In other embodiments, the limiter 154 may not be provided, which is not limited here.

[0049] In some embodiments, the feedback active noise reduction filter 132 may be an IIR structure, or an FIR structure, or a hybrid filter structure of IIR and FIR.

[0050] In the embodiment of the present application, the feedback active noise reduction filter 132 may be an adaptive filter or other filter with adjustable filter configuration, which is not limited here.

[0051] In an embodiment of the present application, the feedforward microphone and / or the feedback microphone may be an analog microphone to collect audio signals in the form of analog signals. In other embodiments, the feedforward microphone and / or the feedback microphone may also be a digital microphone. Accordingly, if the feedforward microphone and / or the feedback microphone are digital microphones, the corresponding active noise reduction channel may not include an analog-to-digital conversion module and an analog gain module.

[0052] For other structures and functions of the active noise reduction headset 100 not described in the above content, reference may be made to the prior art and will not be elaborated here.

[0053] In the embodiment of the present application, the processor of the active noise reduction headset is used to execute the active noise reduction method provided in the embodiment of the present application. Figure 4 , Figure 4 This is a flow chart of an active noise reduction method provided in an embodiment of the present application. The active noise reduction method includes:

[0054] S110, obtaining a current first transfer function value.

[0055] The current first transfer function value is the value of the transfer function between the speaker and the feedback microphone in the current wearing mode. The first transfer function value can be used to determine whether the active noise reduction headset is worn. Among them, the first transfer function Sz is the transfer function between the speaker and the feedback microphone, which can be obtained by collecting the audio signals at the speaker and the feedback microphone respectively, and taking the audio signal of the speaker as input and the audio signal of the feedback microphone as output, and calculating the transfer function between the two.

[0056] The feedback microphone is an in-ear microphone used to collect sound from the cavity formed between the earphone and the ear canal. The speaker can play audio into the ear canal, and the audio signal collected by the feedback microphone will include some audio components played by the speaker. When the active noise reduction earphones are worn and not worn, the audio signals collected by the feedback microphone will be different, and the corresponding first transfer function values ​​under different wearing methods will also be different. Therefore, it is possible to determine whether the earphones are being worn by the first transfer function value between the speaker and the feedback microphone.

[0057] S120: Adjust the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value.

[0058] In the embodiment of the present application, after obtaining the current first transfer function value, the IIR filter 1222 may be adjusted to a target configuration corresponding to the current first transfer function value.

[0059] In this embodiment, the target configuration is obtained after experimentation based on a prototype of an active noise reduction headset, and the prototype has the same structure as the active noise reduction headset. Among them, the prototype of the active noise reduction headset is in any wearing mode, and the prototype is in the target configuration corresponding to the wearing mode, and the noise reduction effect of the prototype of the active noise reduction headset meets the preset noise reduction effect required to be achieved in the wearing mode. That is, in the embodiment of the present application, the active noise reduction headset or the prototype can have a better noise reduction effect in the current wearing mode.

[0060] In one embodiment, adjusting the IIR filter 1222 to a target configuration corresponding to the current first transfer function value may include: determining the target configuration from a preset first corresponding relationship based on the current first transfer function value, and then adjusting the IIR filter according to the target configuration.

[0061] In this embodiment, the first corresponding relationship includes different configurations of IIR filters corresponding to different first transfer function values, and the noise reduction effect achieved by the configuration of the IIR filter 1222 corresponding to each first transfer function value satisfies the preset noise reduction effect required to be achieved by the prototype in the wearing mode corresponding to the first transfer function value, that is, a certain degree of noise reduction effect can be achieved, and the noise reduction effect is obtained by testing in an experiment using a prototype of an active noise reduction headset.

[0062] As mentioned above, different wearing methods will result in different first transfer function values. Therefore, in the embodiments of the present application, different transfer function values ​​can be used to represent wearing methods (or different wearing methods) in different scenarios, and a first correspondence between different transfer function values ​​and different wearing methods can be established in advance. Therefore, when determining the target wearing method, the current first transfer function value under the current wearing method can be calculated first, and then the target configuration corresponding to the current first transfer function value can be determined from the first correspondence.

[0063] The first correspondence is pre-configured and can be obtained by pre-testing and adjusting. Usually, the values ​​of the first transfer function corresponding to different wearing methods are different. Therefore, in one embodiment, the first correspondence is obtained by: simulating the prototype of the active noise reduction headset in different wearing methods respectively; for each wearing method: obtaining the first transfer function value corresponding to the wearing method; adjusting the configuration of the IIR filter 1222 until the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the wearing method, and recording the adjusted configuration of the IIR filter 1222; establishing the correspondence between the first transfer function values ​​corresponding to different wearing methods and the adjusted configuration of the IIR filter 1222 under the different wearing methods, and obtaining the first correspondence.

[0064] Alternatively, the first correspondence can be determined in the following manner: when the noise reduction effect achieved by the prototype of the active noise reduction headset in multiple wearing methods and under the configuration of multiple IIR filters meets the preset noise reduction effect to be achieved, the first transfer function values ​​of the prototype in various wearing methods are measured respectively, and then the first transfer values ​​are compared with the corresponding IIR filter configurations to form a first correspondence.

[0065] In this embodiment, the prototype of the active noise reduction headset can be worn on the ear of a volunteer or an artificial ear, and the position of the prototype can be adjusted so that it can simulate different wearing methods.

[0066] For each wearing mode, the audio signal output by the speaker and the audio signal collected by the feedback microphone may be collected first, and a first transfer function value between the two may be calculated and recorded.

[0067] Then, adjust the IIR filter 1222 in the prototype until the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the current wearing method. Among them, the noise reduction effect of the active noise reduction headphones can be judged based on the audio signals collected by the feedback microphone and the feedforward microphone. The feedforward microphone is an external microphone, and the feedback microphone is an external microphone. When the prototype turns on active noise reduction, the difference between the audio signal collected by the feedforward microphone and the audio signal collected by the feedback microphone can represent the signal difference after the noise reduction is turned on. When the active noise reduction is not turned on, the difference between the audio signals collected by the two microphones can represent the signal difference when the noise reduction is not turned on. Based on the signal difference after the noise reduction is turned on and the signal difference when the noise reduction is not turned on, the noise reduction amount of the prototype, that is, the noise reduction effect, can be determined.

[0068] Since the active noise reduction headphones and prototypes mainly reduce noise in the frequency bands below 2KHz and 3KHz, when calculating the noise reduction amount, the noise reduction amounts of different frequency bands can be calculated separately, and then different weights can be set to weightedly calculate the total noise reduction amount. At the same time, multiple prototypes of active noise reduction headphones with the same configuration can be used to test the noise reduction amount separately, and then the noise reduction amounts of different prototypes can be weighted to obtain the final noise reduction amount.

[0069] In some embodiments, whether the noise reduction effect of the active noise reduction headphones matches the noise reduction effect required to be achieved in the current wearing method can be determined by: the noise reduction amount of the prototype reaches a preset value, or the noise reduction capability of the prototype reaches a maximum.

[0070] The preset value can be 20db, 30db, 40db, etc., and the noise reduction requirements are configured according to the actual application scenarios. The preset values ​​corresponding to different wearing methods may be different. For example, under normal wearing, the headphones already have a certain noise reduction effect due to their obstruction of external sounds. Therefore, a lower preset value can be set. When not worn normally, external sounds may be heard by the user through the gap between the headphones and the ears. Therefore, a larger preset value can be set.

[0071] When the noise reduction capability of the prototype reaches its maximum, the prototype can no longer further improve its noise reduction capability. Therefore, it can be directly regarded as the noise reduction effect at this time reaching the optimal one, and the noise reduction effect of the prototype matches the noise reduction effect required to be achieved by the current wearing method.

[0072] Through the preset first corresponding relationship, a better noise reduction effect can be achieved under the selected target configuration (such as the preset noise reduction effect needs to be achieved under the target configuration). Especially compared with the fixed IIR filter, the embodiment of the present application can adjust the noise reduction capability of the IIR filter, thereby improving the active noise reduction effect. In addition, based on the selected target configuration, especially at low frequencies (such as frequency bands below 200Hz, 300Hz, and 400Hz), there is a good active noise reduction effect. When the IIR filter is of a low order, such as 4th order, 6th order, 8th order, etc., it can still make significant adjustments to the low-frequency band of the audio signal under appropriate configuration, so that the feedforward active noise reduction filter can achieve a preset noise reduction effect by adjusting the noise reduction capability of the IIR filter. The chip area and power consumption required for this method are often smaller than the chip area and power consumption required for further adjusting the noise reduction capability of the FIR filter when the FIR filter has a certain noise reduction capability when the same preset noise reduction effect needs to be achieved. Therefore, the requirements for the order of the FIR can be reduced, so that the adjustment of the FIR filter mainly affects the active noise reduction effect of the low-frequency band (such as 100hz, 200Hz, 300Hz).

[0073] Therefore, in different wearing methods (which may correspond to different first transfer function values), the active noise reduction effect in different wearing methods can be improved by selecting the target configuration of the IIR filter, such as each target configuration of the IIR filter 1222 can achieve a preset noise reduction effect. Among them, the preset noise reduction effect here is not the final noise reduction effect, but the noise reduction effect that the active noise reduction headphones need to achieve when only the IIR filter 1222 is adjusted. The noise reduction effect is the expected and desired effect, which can be obtained by experimental measurement or configured according to demand. After adjusting in combination with the FIR filter 1221, the noise reduction effect achieved by the active noise reduction headphones is the final noise reduction effect.

[0074] In addition, it should be noted that when considering the noise reduction effect, the present application does not consider the noise reduction effect achieved by the feedback active noise reduction channel. If this is considered, the noise reduction effect of the active noise reduction headphones will be further changed. This content is not within the scope of consideration of the present application and will not be further elaborated here.

[0075] S130, estimating a current overall frequency response that the feedforward active noise reduction filter needs to achieve under a current first transfer function value.

[0076] Different from the preset noise reduction effect required to be achieved by the current wearing mode under the target configuration of the aforementioned IIR filter 1222, in the embodiment of the present application, the current overall frequency response refers to the effect expected to be achieved after simultaneously adjusting the IIR filter 1222 and the FIR filter 1221. At this time, the configuration of the FIR filter 1221 cannot be determined, so the current overall frequency response obtained at this time is an estimated result, which is an expected and ideal result.

[0077] In the active noise reduction headset, the overall frequency response of the feedforward active noise reduction filter is actually determined by the configuration of the FIR filter 1221 and the IIR filter 1222. However, the overall frequency response of the feedforward active noise reduction filter also affects the error signal, which is calculated by the overall frequency response, the first transfer function and the second transfer function. Therefore, the overall frequency response can be calculated by the first transfer function and the second transfer function. The second transfer function is the transfer function between the feedforward microphone and the feedback microphone.

[0078] Therefore, in one embodiment, estimating the current overall frequency response that the feedforward active noise reduction filter needs to achieve in the current wearing mode may include:

[0079] Obtain an estimated error signal; obtain a current second transfer function value, wherein the current first transfer function value is the value of the transfer function between the speaker and the feedback microphone in the current wearing mode; the current second transfer function value is the value of the transfer function between the feedforward microphone and the feedback microphone in the current wearing state; determine the current overall frequency response based on the error signal, the current first transfer function value, the current second transfer function value, and the second preset relationship, wherein the second preset relationship includes a conversion relationship between the error signal, the first transfer function value, the second transfer function value, and the overall frequency response.

[0080] The current first transfer function value can be measured after the user wears the headset, based on the music signal, prompt sound signal, call voice signal, etc. played by the speaker. The current second transfer function value can be measured when the user wears the headset and the active noise reduction is turned off, based on the audio signal collected by the feedforward microphone and the audio signal collected by the feedback microphone.

[0081] In some scenarios, the active noise reduction headset may need to perform noise reduction before playing music, prompt sounds, etc. At this time, the current first transfer function value can be determined in the following way when the active noise reduction is turned on:

[0082] Sz=(FB_in–FF_in*Pz) / Y

[0083] Wherein, FF_in is the audio data collected by the feedforward microphone, FB_in is the audio data collected by the feedback microphone, Y is the input signal played by the speaker, Y includes the reverse noise signal played by the speaker to offset the noise in the ear during active noise reduction, Sz is the first transfer function value, and Pz is the second transfer function value.

[0084] The error signal is the ambient sound in the ear when active noise reduction is turned on. The smaller the error signal, the better the noise reduction effect. In the embodiment of the present application, estimating the error signal is to estimate the noise reduction effect that the active noise reduction is ultimately required to achieve. Therefore, the error signal can be estimated according to actual needs, for example, the error signal is less than a preset threshold.

[0085] In the embodiment of the present application, the second preset relationship is the calculation relationship between the error signal, the first transfer function value, and the current second transfer function value. The error signal may be collected by different microphones, and the calculation method of the error signal collected by different microphones is different, and the second preset relationship is different.

[0086] In one embodiment, the error signal may be collected by a feedback microphone, and the second preset relationship may be expressed as:

[0087] E1=FF_in*[Pz-FF_W*Sz] / (1+FB_W*Sz)

[0088] Among them, E1 is the error signal, FF_in is the audio signal collected by the feedforward microphone; FB_W is the feedback noise reduction filter coefficient; FF_W is the overall frequency response of the feedforward active noise reduction filter; Pz is the second transfer function, Sz is the first transfer function, * can represent convolution in the time domain, and multiplication in the frequency domain, Z domain and other transformations.

[0089] In one embodiment, the error signal may be the ambient sound at a preset virtual microphone when active noise reduction is turned on.

[0090] The feedforward microphone in the present application may be one or more feedforward microphones, which are often referred to as external ear microphones, and are usually located near the outer shell of the active noise reduction headset to collect audio data outside the ear of the wearer. The feedback microphone is often referred to as an in-ear microphone, which is usually located on the inner side of the active noise reduction headset near the ear canal to collect audio data inside the ear. The virtual microphone in the present application refers to the position of the ear canal between the ear canal side and the eardrum when the user wears the headset, and particularly refers to the position of the ear canal close to the eardrum. The virtual microphone in the present application refers to placing a microphone independent of the headset at the virtual microphone for collecting audio signals, or refers to placing a microphone independent of the headset at the virtual microphone, and the audio signal that can be collected by the microphone is the audio signal collected by the virtual microphone.

[0091] Accordingly, based on the audio signal collected by the virtual microphone, the second preset relationship can be expressed as:

[0092] E1=FF_in*[Pz*Cp+Pz*FB_W*Sz*(Cp-Cs)-FF_W*Sz*Cs] / (1+FB_W*Sz)

[0093] Among them, Cp is the transfer function between the FB microphone and the virtual microphone, Cs is the transfer function between the FB microphone and the virtual microphone, and the other parameters are the same as above.

[0094] Cp is the transfer function between the input and output of the external ambient sound of the headphones, which is transmitted to the feedback microphone and the virtual microphone respectively after the user wears the headphones. The input is the audio signal collected by the FB microphone, and the output is the audio signal collected by the virtual microphone.

[0095] Cs is the audio signal played by the headphone speaker after the user wears the headphone, which is transmitted to the feedback microphone and the virtual microphone respectively. The input is the audio signal collected by the FB microphone, and the output is the audio signal collected by the virtual microphone, which is the transfer function between the input and the output.

[0096] When end users use active noise reduction headphones, they may not configure a virtual microphone. Therefore, the virtual microphone is actually configured during the design phase, and Cp and Cs are also determined during the design phase. When users use active noise reduction headphones, Cp and Cs are pre-configured fixed values. For each headset, Cp and Cs are obtained by multiple testers using the headset and configuring a microphone independent of the headset at the virtual microphone when the testers wear the headset, and then applied to the headset.

[0097] The above test can be carried out in an audio laboratory. Among them, Cp can be played in the laboratory with the active noise reduction of the headset turned off, and the ambient sound, such as pink noise or various ambient noise scenes, such as a noisy subway or street, can be obtained based on the audio data collected by the feedback microphone and the audio data collected by the independent microphone placed at the virtual microphone. Cs can be obtained by playing an audio signal by a speaker, and then collecting audio data by the feedback microphone and the independent microphone placed at the virtual microphone. In the test phase, the actual Cp and Cs when the user wears it normally are approximated based on the Cp and Cs measured on the prototype. However, due to different headsets, differences between users and testers, and different wearing methods, there will be errors between the two. In the calculation of the aforementioned overall frequency response, the Cp and Cs used are the Cp and Cs measured on the prototype, which are approximations of the Cp and Cs when the user wears the headset. For details, please refer to the prior art, which will not be expanded here.

[0098] The desired overall frequency response can be determined by the estimated error signal, the current first transfer function value and the current second transfer function value determined by the audio signals collected by each microphone, and the second preset relationship.

[0099] In some embodiments of the present application, obtaining the error signal may include: minimizing the error signal. The minimum value of the error signal is 0, and minimizing the error signal is to make the error signal equal to 0. When the error signal is minimum, at this time, based on the minimized error signal, the current first transfer function value and the current second transfer function value, and the second preset relationship, determining the current overall frequency response can enable the active noise reduction headphones to achieve the theoretically optimal noise reduction effect.

[0100] Meanwhile, for the ambient sound at the feedback microphone as the error signal, the second preset relationship can be expressed as: FF_W = Pz / Sz. For the ambient sound at the virtual microphone as the error signal, the second preset relationship can be expressed as: FF_W = [Pz*Cp+Pz*FB_W*Sz*(Cp-Cs)] / (Sz*Cs).

[0101] S140, determining a target frequency response of the FIR filter based on the target configuration and the current overall frequency response.

[0102] The overall frequency response of the feedforward active noise reduction filter is determined by the frequency response of the internal IIR filter 1222 and the frequency response of the FIR filter 1221 .

[0103] For example, if the IIR filter 1222 and the FIR filter 1221 are connected in parallel, the overall frequency response = IIR filter frequency response + FIR filter frequency response.

[0104] If the IIR filter 1222 and the FIR filter 1221 are connected in series, the overall frequency response = IIR filter frequency response * FIR filter frequency response.

[0105] The relationship between the overall frequency response of the feedforward active noise reduction filter and its internal filter structure can be referred to the prior art and will not be elaborated here. In the embodiment of the present application, the frequency response of the FIR filter 1221 can be calculated in reverse by the IIR filter frequency response and the overall frequency response of the feedforward active noise reduction filter.

[0106] S150, adjusting the FIR filter based on the target frequency response, so as to perform noise reduction using the adjusted FIR filter.

[0107] In the embodiment of the present application, the target frequency response is converted into a frequency domain and a time domain to obtain the coefficients of the FIR filter 1221, and then the FIR filter 1221 is configured based on the obtained coefficients of the FIR filter 1221 to complete the adjustment of the FIR filter 1221. The frequency domain and time domain conversion can be an inverse fast Fourier transform, an inverse discrete Fourier transform, etc. The relationship between the frequency response and the filter coefficient can refer to the prior art and will not be expanded here.

[0108] In one embodiment of the present application, adjusting the FIR filter 1221 based on the target frequency response may include: converting the target frequency response into a target FIR filter 1221 coefficient group of the FIR filter 1221; wherein the target FIR filter 1221 coefficient group includes: among a plurality of consecutive FIR filter 1221 coefficients, N1 FIR filter 1221 coefficients between every two non-zero FIR filter 1221 coefficients are 0, and N1 is a positive integer; adjusting the FIR filter 1221 according to the target FIR filter 1221 coefficient group to obtain an adjusted FIR filter 1221.

[0109] In the embodiment of the present application, the target FIR filter 1221 coefficient group has N1 FIR filter 1221 coefficients between each two non-zero FIR filter 1221 coefficients in a continuous plurality of FIR filter 1221 coefficients, and the coefficients are 0. For example, when N1 is 3, there are 3 FIR filter 1221 coefficients with a value of 0 between each two non-zero FIR filter 1221 coefficients. N1 can be a positive integer, such as 3, 7, 11, 15, etc., and can be configured according to requirements.

[0110] The coefficient of the FIR filter 1221 is 0, which can reduce the amount of calculation of the FIR filter 1221 and improve the calculation efficiency. Among the FIR filters 1221 of the same order, the coefficients of some FIR filters 1221 are 0, which can reduce the power consumption generated by filtering. Since the order of the FIR filter 1221 can remain unchanged, the FIR filter 1221 can still have a better active noise reduction performance for medium and low frequencies (such as below 500 Hz).

[0111] The IIR filter 1222 and the FIR filter 1221 operate at the first sampling rate f1. In one embodiment, the target FIR filter 1221 coefficient group can be obtained as follows:

[0112] When estimating the current overall frequency response, estimate the current overall frequency response corresponding to the second sampling rate under the current first transfer function value, then determine the target frequency response based on the current overall frequency response and the target configuration under the second sampling rate, and finally, convert the target frequency response into multiple FIR filter 1221 coefficients; insert N1 FIR filter 1221 coefficients with a value of 0 between every two adjacent FIR filter 1221 coefficients to obtain a target FIR filter 1221 coefficient group; wherein, N1 = second sampling rate / first sampling rate - 1.

[0113] The second sampling rate is less than the first sampling rate, the second sampling rate matches the sampling rate of the non-zero FIR filter 1221 coefficients, and the first sampling rate matches the sampling rate of all FIR filter 1221 coefficients including 0 and non-0 in the target FIR filter 1221 coefficient group. The target frequency response determined at the second sampling rate is also the second sampling rate, so it can be restored to the first sampling rate by inserting a 0 value, and the FIR filter 1221 coefficients of 0 are also inserted.

[0114] IIR filter 1222 and FIR filter 1221 are two filters with different structures, both of which can perform filtering and noise reduction, but the noise reduction effects of the two are different in different frequency bands, and the two are usually used to reduce the noise of audio signals in different frequency bands. FIR filter 1221 is mainly used to reduce the noise of audio signals in the low-frequency band. When actively reducing noise, the noise is usually a low-frequency signal. Therefore, usually only the configuration of FIR filter 1221 is adjusted to achieve noise reduction of low-frequency signals. However, when the noise reduction ability of FIR filter 1221 reaches a certain level, if FIR filter 1221 needs to further adjust the noise reduction ability, it may be necessary to make FIR filter 1221 have a higher order, occupy a larger chip area, and generate greater power consumption. In the embodiment of the present application, the IIR filter 1222 is configured as an adjustable configuration filter. Although the IIR filter 1222 has a better noise reduction effect in the high-frequency band, it still has a certain noise reduction effect on the low-frequency band. The noise reduction capability of the IIR filter 1222 is adjusted so that the feedforward active noise reduction filter achieves a preset noise reduction effect. The chip area required and the power consumption generated by this method are both smaller than the chip area and the power consumption required for further adjusting the noise reduction capability of the FIR filter 1221 when the FIR filter 1221 already has a certain noise reduction capability. For example, the FIR filter 1221 is of order 512, and the IIR filter 1222 is of order 256. The noise reduction capability of the FIR filter 1221 reaches a certain threshold. If the noise reduction capability needs to be further improved, it needs to reach order 1024, which requires a larger area and generates higher power consumption. However, if the IIR filter 1222 is adjusted, since the noise reduction capability of the IIR filter 1222 has not yet reached a certain threshold, if the feedforward active noise reduction filter achieves the same performance, adjusting the FIR filter 1221 may only need to reach order 512. Compared with adjusting the FIR filter 1221, the area required and the power consumption generated by adjusting the IIR filter 1222 will be lower.

[0115] Therefore, by adjusting the configuration of the IIR filter 1222, the noise reduction effect of the active noise reduction headphones can meet the preset noise reduction effect required for the current wearing method, and then the configuration of the FIR filter 1221 can be determined and adjusted through the frequency response. This method can reduce the overall chip area and overall power consumption of the feedforward active noise reduction filter.

[0116] In addition, the above method does not need to use an adaptive iterative algorithm, which can effectively avoid the situation where the noise reduction is unstable due to adaptive iteration, and effectively reduce the situation where the configuration adjustment time during active noise reduction is too long due to the convergence of adaptive iteration.

[0117] Based on the same inventive concept, the embodiment of the present application further provides an active noise reduction device 300, which can be applied to the processor of the active noise reduction headset provided in the aforementioned embodiment.

[0118] See also Figure 5 , Figure 5 The active noise reduction device 300 provided in one embodiment of the present application is a schematic diagram. The active noise reduction device 300 includes: a first configuration module 310 , a first calculation module 320 , a second calculation module 330 and a second configuration module 340 .

[0119] The first configuration module 310 is used to obtain the current first transfer function value; the current first transfer function value is the value of the transfer function between the speaker and the feedback microphone in the current wearing mode; based on the current first transfer function value, the IIR filter is adjusted to the target configuration corresponding to the current first transfer function value.

[0120] The first calculation module 320 is used to estimate the current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value.

[0121] The second calculation module 330 is used to determine the target frequency response of the FIR filter 1221 based on the target configuration and the current overall frequency response.

[0122] The second configuration module 340 is used to adjust the FIR filter 1221 based on the target frequency response, so as to use the adjusted FIR filter 1221 to perform noise reduction.

[0123] In one embodiment, the first configuration module 310 is used to determine a target configuration from a preset first correspondence based on the current first transfer function value, the first correspondence including different configurations of the IIR filter corresponding to different first transfer function values; and adjust the IIR filter according to the target configuration.

[0124] In one embodiment, different first function values ​​represent different wearing methods, and the first corresponding relationship configured in the first configuration module 310 is obtained by: simulating the prototype of the active noise reduction headset in different wearing methods respectively; for each wearing method: obtaining the first transfer function value corresponding to the wearing method; adjusting the configuration of the IIR filter 1222 until the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the wearing method, and recording the adjusted configuration of the IIR filter 1222; establishing the corresponding relationship between the first transfer function values ​​corresponding to the different wearing methods and the adjusted configuration of the IIR filter 1222 under the different wearing methods, and obtaining the first corresponding relationship.

[0125] In one embodiment, the noise reduction effect of the active noise reduction headset matches the noise reduction effect required to be achieved by the current wearing method, including: the noise reduction amount of the prototype reaches the preset value, or the noise reduction capability of the prototype reaches the maximum.

[0126] In one embodiment, the second calculation module 330 is used to convert the target frequency response into a target FIR filter 1221 coefficient group of the FIR filter 1221; wherein the target FIR filter 1221 coefficient group includes: among a plurality of consecutive FIR filter 1221 coefficients, there are N1 FIR filter 1221 coefficients of 0 between every two non-zero FIR filter 1221 coefficients, and N1 is a positive integer; the FIR filter 1221 is adjusted according to the target FIR filter 1221 coefficient group to obtain the adjusted FIR filter 1221.

[0127] In one embodiment, the IIR filter 1222 and the FIR filter 1221 operate at a first sampling rate, and the first calculation module 320 is used to estimate the current overall frequency response corresponding to the second sampling rate under the current first transfer function value, and the second sampling rate is less than the first sampling rate. The second calculation module 330 is used to determine the target frequency response based on the current overall frequency response corresponding to the second sampling rate and the target configuration. The second calculation module 330 is also used to convert the target frequency response into a plurality of FIR filter 1221 coefficients; insert N1 FIR filter 1221 coefficients with a value of 0 between each two adjacent FIR filter 1221 coefficients to obtain the target FIR filter 1221 coefficient group; wherein, N1 = second sampling rate / first sampling rate-1.

[0128] The first calculation module 320 is also used to obtain an estimated error signal; obtain a current first transfer function value and a current second transfer function value, wherein the current first transfer function value is the value of the transfer function between the speaker and the feedback microphone in the current wearing mode; the current second transfer function value is the value of the transfer function between the feedforward microphone and the feedback microphone in the current wearing state; determine the current overall frequency response based on the error signal, the current first transfer function value, the current second transfer function value and a second preset relationship, wherein the second preset relationship includes a conversion relationship between the error signal, the first transfer function value, the second transfer function value and the overall frequency response.

[0129] The first calculation module 320 is further configured to minimize the error signal; and determine the current overall frequency response based on the minimized error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship.

[0130] Based on the same inventive concept, an embodiment of the present application further provides a readable storage medium, in which instructions are stored. The instructions can be executed by one or more processors to implement the active noise reduction method provided in the above embodiment.

[0131] The readable storage medium may be any available medium that can be accessed by the processor 110 or a data storage device that includes one or more available media. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a magnetic tape), an optical medium (e.g., a DVD (digital video disc)), or a semiconductor medium (e.g., an SSD (Solid State Disk)).

[0132] If the control method for howling suppression is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, ROM, RAM, disk or optical disk, and other media that can store program codes.

[0133] In the embodiments provided in the present application, it should be understood that the disclosed method can also be implemented in other ways. The functional modules in the various embodiments of the present application can be integrated together to form an independent part, or each module can exist separately, or two or more modules can be integrated to form an independent part.

[0134] The above embodiments can be freely combined without conflict, and the embodiments obtained by the combination are included in the protection scope of this application.

[0135] The above detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0136] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0137] In the description of this application, it is also necessary to explain that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0138] The above description is only an embodiment of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An active noise reduction method, characterized in that: A processor applied to an active noise reduction headset, wherein the active noise reduction headset includes a feedforward active noise reduction filter, a feedback microphone and a speaker, wherein the feedforward active noise reduction filter includes an IIR filter and a FIR filter; The active noise reduction method comprises: Acquire a current first transfer function value; the current first transfer function value is a value of a transfer function between the loudspeaker and the feedback microphone; adjusting the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value; estimating a current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value; Determining a target frequency response of the FIR filter based on the target configuration and the current overall frequency response; The FIR filter is adjusted based on the target frequency response to perform noise reduction using the adjusted FIR filter.

2. The active noise reduction method according to claim 1, characterized in that: The active noise reduction headset also includes a speaker and a feedback microphone; The adjusting the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value comprises: Determining the target configuration from a preset first correspondence relationship based on the current first transfer function value, the first correspondence relationship including different configurations of the IIR filter corresponding to different first transfer function values; The IIR filter is adjusted according to the target configuration.

3. The active noise reduction method according to claim 2, characterized in that: Different first function values ​​represent different wearing methods, and the first corresponding relationship is obtained in the following manner: Simulating the prototype of the active noise reduction headset in different wearing modes respectively; For each wearing mode: obtaining a first transfer function value corresponding to the wearing mode; adjusting the configuration of the IIR filter until the noise reduction effect of the prototype matches the preset noise reduction effect required to be achieved by the wearing mode, and recording the adjusted configuration of the IIR filter; A correspondence between the first transfer function values ​​corresponding to different wearing modes and the adjusted configurations of the IIR filter under different wearing modes is established to obtain the first correspondence.

4. The active noise reduction method according to claim 3, characterized in that: The noise reduction effect of the prototype matches the noise reduction effect required to be achieved by the wearing method, including: the noise reduction amount of the prototype reaches a preset value, or the noise reduction capability of the prototype reaches a maximum.

5. The active noise reduction method according to claim 1, characterized in that: The adjusting the FIR filter based on the target frequency response comprises: Converting the target frequency response into a target FIR filter coefficient group of the FIR filter; wherein the target FIR filter coefficient group includes: among the plurality of continuous FIR filter coefficients, there are N1 FIR filter coefficients of 0 between every two non-zero FIR filter coefficients, and N1 is a positive integer; The FIR filter is adjusted according to the target FIR filter coefficient group to obtain the adjusted FIR filter.

6. The active noise reduction method according to claim 5, characterized in that: The IIR filter and the FIR filter operate at a first sampling rate, and the estimating a current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value includes: estimating a current overall frequency response corresponding to a second sampling rate under the current first transfer function value, the second sampling rate being less than the first sampling rate; The determining the target frequency response of the FIR filter based on the target configuration and the current overall frequency response includes: determining the target frequency response based on the current overall frequency response corresponding to the second sampling rate and the target configuration; The converting the target frequency response into a target FIR filter coefficient group of the FIR filter comprises: Converting the target frequency response into a plurality of FIR filter coefficients; Insert N1 FIR filter coefficients with a value of 0 between every two adjacent FIR filter coefficients to obtain the target FIR filter coefficient group; wherein N1=the second sampling rate / the first sampling rate-1.

7. The active noise reduction method according to any one of claims 1 to 6, characterized in that: The active noise reduction headset includes a feed-forward microphone; The estimating the current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value includes: obtaining an estimated error signal; Acquire a current second transfer function value, where the current second transfer function value is a value of a transfer function between the feedforward microphone and the feedback microphone; The current overall frequency response is determined based on the error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship, wherein the second preset relationship includes a conversion relationship between the error signal, the first transfer function value, the second transfer function value, and the overall frequency response.

8. The active noise reduction method according to claim 7, characterized in that: The obtaining of the estimated error signal comprises: minimizing the error signal; The determining the overall frequency response based on the error signal, the current first transfer function value, the current second transfer function value and a second preset relationship comprises: The current overall frequency response is determined based on the minimized error signal, the current first transfer function value, the current second transfer function value, and a second preset relationship.

9. An active noise reduction device, characterized in that: A processor applied to an active noise reduction headset, wherein the active noise reduction headset includes a feedforward active noise reduction filter, a feedback microphone and a speaker, wherein the feedforward active noise reduction filter includes an IIR filter and a FIR filter; The active noise reduction device comprises: A first configuration module, configured to obtain a current first transfer function value, and adjust the IIR filter to a target configuration corresponding to the current first transfer function value based on the current first transfer function value; wherein the current first transfer function value is a value of a transfer function between the speaker and the feedback microphone; A first calculation module, configured to estimate a current overall frequency response that the feedforward active noise reduction filter needs to achieve under the current first transfer function value; A second calculation module, configured to determine a target frequency response of the FIR filter based on the target configuration and the current overall frequency response; The second configuration module is used to adjust the FIR filter based on the target frequency response to perform noise reduction using the adjusted FIR filter.

10. An active noise reduction headset, characterized in that: include: A feedforward active noise reduction channel, comprising a feedforward microphone and a feedforward active noise reduction filter, wherein the feedforward microphone is connected to the feedforward active noise reduction filter; the feedforward active noise reduction filter comprises an IIR filter and a FIR filter; A feedback active noise reduction channel, comprising a feedback microphone and a feedback active noise reduction filter; A speaker connected to the feedback active noise reduction filter and the feedforward active noise reduction filter; A processor is connected to the feedforward active noise reduction channel and the feedback active noise reduction channel respectively, and is used to execute the active noise reduction method according to any one of claims 1 to 8.

11. A readable storage medium, characterized in that: The readable storage medium stores instructions, and the instructions can be executed by one or more processors to implement the active noise reduction method according to any one of claims 1 to 8.

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