Active noise reduction earphone
By designing feedforward noise reduction channels, feedback noise reduction channels, audio echo filters and processors in noise reduction headphones, the SZ transfer function is estimated in real time and adaptive noise reduction is triggered, which solves the problem of poor noise reduction effect in the existing technology, and achieves better noise reduction effect and user experience.
Patent Information
- Application Number
- CN202311779968.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-12-22
- Publication Date
- 2025-06-24
AI Technical Summary
The existing noise-reducing headphones have poor noise reduction effects when dealing with ambient noise and audio echoes, and the changes in the status of the headphones relative to the ears affect the noise reduction effect.
An active noise reduction headset is designed, including a feedforward noise reduction channel, a feedback noise reduction channel, an audio echo filter and a processor. Audio echo is eliminated through an audio echo filter, and the feedback noise reduction filter generates a reverse noise signal. The processor estimates the SZ transfer function in real time and triggers adaptive noise reduction.
It effectively eliminates the echo interference of the audio to be played, improves the effect of active noise reduction, adapts to changes in the earphones relative to the ear state, and improves the user experience.
Smart Images
Figure CN120201340A_ABST
Abstract
Description
Technical Field
[0001] Embodiments of the present application relate to the technical field of electronic devices, and in particular, to an active noise-canceling headphone. Background Art
[0002] With the progress of society and the improvement of people's living standards, headphones have become an essential daily necessity for people. In order to reduce the interference of ambient noise on the audio signal played in the headphones, noise-canceling headphones have gradually entered people's lives, enabling people to obtain a relatively quiet environment in a noisy environment.
[0003] Under the related technology, the noise-canceling headphone reduces the interference of ambient noise on the audio signal played in the headphone through an active noise-canceling method. Among them, the active noise-canceling method means: the headphone actively emits sound waves with opposite phases to cancel the ambient noise inside the headphone.
[0004] However, in actual applications, in addition to the ambient noise interfering with the audio signal played in the headphone, the echo signal of the audio played in the headphone will also cause interference. In addition, during the process of the user wearing the headphone, the state (position, orientation, tightness, etc.) of the headphone relative to the ear often changes, and the headphone always emits sound waves with the same phase to cancel the ambient noise inside the headphone, resulting in a poor noise-canceling effect. Summary of the Invention
[0005] Embodiments of the present application provide an active noise-canceling headphone for eliminating the echo of the audio to be played and actively canceling noise in combination with the state of the headphone relative to the ear, thereby improving the noise-canceling effect.
[0006] On the one hand, embodiments of the present application provide an active noise-canceling headphone, including:
[0007] A feedforward noise-canceling channel, a feedback noise-canceling channel, an audio echo filter, a processor, and a first superimposing module;
[0008] The audio echo filter is configured to filter the audio signal to be played and output an audio echo signal;
[0009] The feedback noise-canceling channel is configured to generate a reverse noise signal after canceling the echo using the audio echo signal;
[0010] The processor is configured to estimate the SZ transfer function, and when the variation value of the SZ transfer function is greater than a preset threshold, trigger the feedforward noise-canceling channel to start adaptive noise cancellation and output a forward noise signal for noise cancellation. The SZ transfer function refers to the transfer function between the input signal of the playback module in the active noise-canceling headphone and the feedback audio signal collected by the feedback noise-canceling channel;
[0011] The first superposition module is configured to superpose the audio signal to be played, the reverse noise signal, and the forward noise signal, and output a target audio signal.
[0012] Optionally, the feedback noise reduction channel includes: a feedback acquisition and conversion module, a feedback noise reduction filter, and a second superposition module;
[0013] The second superposition module is configured to superpose the converted audio signal output by the feedback acquisition and conversion module and the audio echo signal, and output a first noise signal;
[0014] The feedback noise reduction filter is configured to filter the first noise signal and output the reverse noise signal.
[0015] Optionally, when the processor executes the estimation of the SZ transfer function, it is specifically configured to:
[0016] Estimate the SZ transfer function based on the audio signal to be played, the converted audio signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter;
[0017] The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, and the sampling frequencies of the audio signal to be played and the converted audio signal are both second sampling frequencies, and the ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
[0018] Optionally, when the processor executes the estimation of the SZ transfer function based on the audio signal to be played, the converted audio signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, it is specifically configured to:
[0019] Estimate a first transfer function with the audio signal to be played as the input and the converted audio signal as the output;
[0020] Estimate the SZ transfer function based on the first transfer function, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter.
[0021] Optionally, when the processor executes the estimation of the SZ transfer function, it is specifically configured to:
[0022] Estimate the SZ transfer function based on the audio signal to be played, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter;
[0023] The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, and the sampling frequency of the audio signal to be played is a second sampling frequency, and the ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
[0024] Optionally, when the processor estimates the SZ transfer function based on the audio signal to be played, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, it specifically is used for:
[0025] Filter and downsample the first noise signal through a low-pass filtering and downsampling module to obtain a second noise signal, and the sampling frequency corresponding to the second noise signal is a second sampling frequency;
[0026] Use the audio signal to be played as the input and the second noise signal as the output to estimate a second transfer function;
[0027] Estimate the SZ transfer function based on the second transfer function, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter.
[0028] Optionally, when the processor estimates the SZ transfer function, it specifically is used for:
[0029] Estimate the SZ transfer function based on the audio signal to be played, the converted audio signal, and the reverse noise signal;
[0030] The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, the sampling frequencies corresponding to the audio signal to be played and the converted audio signal are both second sampling frequencies, and the ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
[0031] Optionally, when the processor estimates the SZ transfer function based on the audio signal to be played, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, it specifically is used for:
[0032] Filter and downsample the reverse noise signal through a low-pass filtering and downsampling module to obtain a third noise signal, and the sampling frequency corresponding to the third noise signal is a second sampling frequency;
[0033] Use the audio signal to be played as the input and the converted audio signal as the output to estimate a first transfer function; use the audio signal to be played as the input and the third noise signal as the output to estimate a third transfer function;
[0034] Estimate the SZ transfer function based on the first transfer function and the third transfer function.
[0035] Optionally, when the processor estimates the SZ transfer function, it specifically is used for:
[0036] Estimate the SZ transfer function based on the to-be-played audio signal, the converted audio signal, and the target audio signal. The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, and the sampling frequencies of the to-be-played audio signal and the converted audio signal are both a second sampling frequency. The ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
[0037] Optionally, when the processor executes the estimation of the SZ transfer function based on the to-be-played audio signal, the converted audio signal, and the target audio signal, it is specifically configured to:
[0038] Filter and downsample the target audio signal through a low-pass filtering and downsampling module to obtain a fourth noise signal, and the sampling frequency of the fourth noise signal is the second sampling frequency;
[0039] Use the to-be-played audio signal as the input and the converted audio signal as the output to estimate a first transfer function; use the to-be-played audio signal as the input and the fourth noise signal as the output to estimate a fourth transfer function;
[0040] Estimate the SZ transfer function based on the first transfer function and the fourth transfer function.
[0041] In the embodiments of the present application, during the active noise reduction process, the to-be-played audio signal is filtered through an audio echo filter to output an audio echo signal. Then, the converted audio signal output by the feedback acquisition conversion module is superimposed on the audio echo signal to eliminate the interference of the echo of the to-be-played audio signal and obtain a first noise signal; then, the first noise signal is filtered through a feedback noise reduction filter to output a reverse noise signal for noise reduction, thereby improving the effect of active noise reduction using the reverse noise signal. Secondly, by estimating the SZ transfer function in real time, the real-time monitoring of the state of the earphone relative to the ear is realized; and when it is monitored that the change in the SZ transfer function reaches a certain value, the feedforward noise reduction channel is triggered to start adaptive noise reduction and output a forward noise signal matching the current SZ transfer function. Therefore, when using the matching forward noise signal for active noise reduction, it is more matched with the current state of the earphone relative to the ear, so the noise reduction effect is better and the user experience is better. Description of the Drawings
[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.
[0043] Figure 1A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0044] Figure 2 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0045] Figure 3 A schematic diagram of the structure of an active noise reduction headset provided in an embodiment of the present application;
[0046] Figure 4 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION
[0047] In order to make the purpose, technical solution and beneficial effects of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.
[0048] refer to Figure 1 , which is a schematic diagram of the structure of an active noise reduction headset provided by the present application, the active noise reduction headset 100 includes:
[0049] Feedforward noise reduction channel 101, feedback noise reduction channel 102, audio echo filter 103, processor 104, first superposition module 105;
[0050] The audio echo filter 103 is used to filter the audio signal to be broadcast and output an audio echo signal;
[0051] Feedback noise reduction channel 102, used to generate a reverse noise signal after echo cancellation using the audio echo signal;
[0052] The processor 104 is used to estimate the SZ transfer function, and when the variation value of the SZ transfer function is greater than a preset threshold, trigger the feedforward noise reduction channel 101 to start adaptive noise reduction and output a forward noise signal for noise reduction.
[0053] The first superposition module 105 is used to superpose the to-be-broadcast audio signal, the reverse noise signal and the forward noise signal to output a target audio signal.
[0054] Specifically, the active noise reduction earphone 100 can be an in-ear earphone, a semi-in-ear earphone, or an earphone in a true wireless stereo (TWS) earphone, an earphone in a headphone, etc.
[0055] The to-be-played audio signal is obtained by performing low-pass filtering and downsampling on the audio source signal. The SZ transfer function refers to the transfer function between the input signal of the playback module in the active noise-canceling headphone 100 and the feedback audio signal collected by the feedback noise-canceling channel 102. When the state (position, orientation, tightness, etc.) of the headphone relative to the ear changes, the SZ transfer function often changes as well. The playback module includes: a digital-to-analog conversion module, a power amplifier module, a speaker, etc.
[0056] In some embodiments, referring to Figure 2 , the feedforward noise-canceling channel 101 includes: a feedforward acquisition and conversion module 201, a feedforward noise-canceling filter 202, and an adaptive control module 203.
[0057] Specifically, the feedforward acquisition and conversion module 201 collects audio data outside the ear through an external ear microphone. The audio data outside the ear includes, but is not limited to, environmental noise signals and audio signals leaked outside the ear played by the headphone speaker. Then, the collected audio data is subjected to gain processing, analog-to-digital conversion processing, low-pass filtering, and downsampling processing, etc.
[0058] The feedforward noise-canceling filter 202 is an adaptive filter; the adaptive control module 203 iteratively updates the filter coefficients of the feedforward noise-canceling filter 202 through an adaptive algorithm.
[0059] In addition, the feedforward noise-canceling filter 202 can be a non-recursive filter or a recursive filter; it can also be a filter structure that combines both a non-recursive filter and a recursive filter.
[0060] It should be noted that when the feedforward noise-canceling filter 202 is a filter structure that combines multiple filters, all the filters in the filter structure can be adaptive filters; or some filters can be adaptive filters, and the other filters can be filters with fixed coefficients. Moreover, the multiple filters in the filter structure can be connected in series or in parallel. In this regard, the present application does not make specific limitations.
[0061] The audio echo filter 103 can be an adaptive filter or a filter with fixed coefficients. In addition, the audio echo filter 103 can be a non-recursive filter or a recursive filter; it can also be a filter structure that combines both a non-recursive filter and a recursive filter.
[0062] The specific operation method in the first superposition module 105 can be set according to the actual situation, such as addition, subtraction, etc., or other combined operations. In this regard, the present application does not make specific limitations.
[0063] For example, the first superimposing module 105 subtracts the reverse noise signal and the forward noise signal from the audio signal to be played, outputs the target audio signal, and then outputs the target audio signal to the playback module for playback.
[0064] When the forward feed noise reduction channel 101 does not output a forward noise signal, the first superimposing module 105 superimposes the audio signal to be played and the reverse noise signal, and outputs the target audio signal. Specifically, the first superimposing module 105 subtracts the reverse noise signal from the audio signal to be played, outputs the target audio signal, and then outputs the target audio signal to the playback module for playback.
[0065] In some embodiments, referring to Figure 3 , the feedback noise reduction channel 102 includes: a feedback acquisition and conversion module 301, a feedback noise reduction filter 302, and a second superimposing module 303.
[0066] The second superimposing module 303 is configured to superimpose the converted audio signal output by the feedback acquisition and conversion module 301 and the audio echo signal, and output a first noise signal;
[0067] The feedback noise reduction filter 302 is configured to filter the first noise signal and output a reverse noise signal.
[0068] Specifically, the feedback acquisition and conversion module 301 collects audio data inside the earphone through an in-ear microphone. The audio data inside the earphone includes, but is not limited to, environmental noise signals and audio signals played by the earphone speaker. Then, the collected audio data is subjected to gain processing, analog-to-digital conversion processing, low-pass filtering, and downsampling processing, and the converted audio signal is output.
[0069] The feedback noise reduction filter 302 can be an adaptive filter or a filter with a fixed coefficient. In addition, the feedback noise reduction filter 302 can be a non-recursive filter or a recursive filter; it can also be a filter structure that combines both a non-recursive filter and a recursive filter.
[0070] In addition, the specific operation method in the second superimposing module 303 can be set according to the actual situation, such as addition, subtraction, etc., or other combined operations. In this regard, the present application does not make specific limitations.
[0071] For example, the feedback acquisition and conversion module 301 outputs the converted audio signal to the second superimposing module 303; the audio echo filter 103 outputs the audio echo signal to the second superimposing module 303; the second superimposing module 303 subtracts the audio echo signal from the converted audio signal and outputs the first noise signal.
[0072] In practical applications, the feedback noise reduction filter 302, the feedforward noise reduction filter 202, and the audio echo filter 103 are implemented by hardware circuits. The hardware circuits refer to: Application Specific Integrated Circuit (ASIC), Field Programmable Gate Array (FPGA), etc. The hardware circuits can ensure real-time performance, with advantages such as low latency, low power consumption, and fixed latency, and can meet the low latency and fixed latency requirements of the active noise reduction channels (including the feedforward noise reduction channel 101, the feedback noise reduction channel 102, and the audio echo filter 103), thereby ensuring the performance of active noise reduction.
[0073] In the embodiments of the present application, during the active noise reduction process, the audio echo filter is used to filter the audio signal to be played, and an audio echo signal is output. Then, the converted audio signal output by the feedback acquisition conversion module is superimposed on the audio echo signal to eliminate the interference of the echo of the audio signal to be played, and a first noise signal is obtained; then, the first noise signal is filtered by the feedback noise reduction filter, and a reverse noise signal for noise reduction is output, thereby improving the effect of active noise reduction using the reverse noise signal. Secondly, by estimating the SZ transfer function in real time, the real-time monitoring of the state of the earphone relative to the ear is realized; and when it is detected that the change in the SZ transfer function reaches a certain value, the feedforward noise reduction channel is triggered to start adaptive noise reduction, and a forward noise signal matching the current SZ transfer function is output. Therefore, when active noise reduction is performed using the matching forward noise signal, it is more matched with the current state of the earphone relative to the ear, so the noise reduction effect is better and the user experience is better.
[0074] For the process of processing and estimating the SZ transfer function, the present application provides at least the following implementation manners:
[0075] Embodiment 1: Estimate the SZ transfer function based on the audio signal to be played, the converted audio signal, the transfer function of the audio echo filter 103, and the transfer function of the feedback noise reduction filter 302.
[0076] The feedforward noise reduction filter 202 in the feedforward noise reduction channel 101 operates at a first sampling frequency f1, and the sampling frequencies of the audio signal to be played and the converted audio signal are both the second sampling frequency f2. The ratio of the first sampling frequency f1 to the second sampling frequency f2 is a positive integer greater than 1.
[0077] For example, the first sampling frequency f1 can be 768KHz, 384KHz, 192KHz, etc., and correspondingly, the second sampling frequency f2 can be 48KHz, 32KHz, 16KHz, etc.
[0078] The transfer function of the feedback noise reduction filter 302 is: the transfer function of the feedback noise reduction filter 302 at the second sampling frequency f2.
[0079] Taking the audio signal to be played as the input, converting the audio signal as the output, and estimating the first transfer function; that is, the first transfer function is the transfer function between the audio signal to be played and the converted audio signal. The estimation method of the first transfer function can be adaptive iteration, such as least mean square, recursive least mean square, normalized least mean square, etc.; it can also be other time-domain, frequency-domain, Z-domain methods, etc.
[0080] Based on the first transfer function, the transfer function of the audio echo filter 103, and the transfer function of the feedback noise reduction filter 302, estimate the SZ transfer function, as specifically shown in the following formula (1):
[0081] Sz = Fir1 / [1 + FB * (MC - Fir1)] …………… (1)
[0082] Wherein, Fir1 represents the first transfer function, FB represents the transfer function of the feedback noise reduction filter 302, and MC represents the transfer function of the audio echo filter 103.
[0083] In the embodiments of the present application, when both the feedback noise reduction channel and the audio echo filter are in the working state, combining the influences of the feedback noise reduction channel and the audio echo filter on the SZ transfer function to estimate the SZ transfer function, thereby improving the accuracy of estimating the SZ transfer function, and further improving the active noise reduction effect.
[0084] Embodiment 2. Estimate the SZ transfer function based on the audio signal to be played, the first noise signal, the transfer function of the audio echo filter 103, and the transfer function of the feedback noise reduction filter 302;
[0085] The feedforward noise reduction filter 202 in the feedforward noise reduction channel 101 operates at the first sampling frequency f1, the sampling frequency corresponding to the audio signal to be played is the second sampling frequency f2, and the ratio of the first sampling frequency f1 to the second sampling frequency f2 is a positive integer greater than 1.
[0086] Filter and downsample the first noise signal through the low-pass filtering and downsampling module to obtain the second noise signal, and the sampling frequency corresponding to the second noise signal is the second sampling frequency f2.
[0087] Taking the audio signal to be played as the input and the second noise signal as the output, estimate the second transfer function; that is, the second transfer function is the transfer function between the audio signal to be played and the second noise signal. The estimation method of the second transfer function can be adaptive iteration, such as least mean square, recursive least mean square, normalized least mean square, etc.; it can also be other time-domain, frequency-domain, Z-domain methods, etc.
[0088] Estimate the SZ transfer function based on the second transfer function, the transfer function of the audio echo filter 103, and the transfer function of the feedback noise reduction filter 302, specifically as shown in the following formula (2):
[0089] Sz = (Fir2 + MC) / (1 - FB * Fir2) …………… (2)
[0090] Wherein, Fir2 represents the second transfer function, FB represents the transfer function of the feedback noise reduction filter 302, and MC represents the transfer function of the audio echo filter 103.
[0091] In the embodiments of the present application, when both the feedback noise reduction channel and the audio echo filter are in the working state, the SZ transfer function is estimated by combining the influence of the feedback noise reduction channel and the audio echo filter on the SZ transfer function, thereby improving the accuracy of estimating the SZ transfer function, and further improving the active noise reduction effect.
[0092] Embodiment 3: Estimate the SZ transfer function based on the to-be-played audio signal, the converted audio signal, and the reverse noise signal.
[0093] The feedforward noise reduction filter 202 in the feedforward noise reduction channel 101 operates at the first sampling frequency f1, and the sampling frequencies of the to-be-played audio signal and the converted audio signal are both the second sampling frequency f2. The ratio of the first sampling frequency f1 to the second sampling frequency f2 is a positive integer greater than 1.
[0094] The reverse noise signal is filtered and downsampled by the low-pass filtering and downsampling module to obtain a third noise signal, and the sampling frequency of the third noise signal is the second sampling frequency f2.
[0095] Estimate the first transfer function with the to-be-played audio signal as the input and the converted audio signal as the output.
[0096] Estimate the third transfer function with the to-be-played audio signal as the input and the third noise signal as the output, that is, the third transfer function is the transfer function between the to-be-played audio signal and the third noise signal. The estimation method of the third transfer function can be adaptive iteration, such as least mean square, recursive least mean square, normalized least mean square, etc.; it can also be other time-domain, frequency-domain, Z-domain methods, etc.
[0097] Estimate the SZ transfer function based on the first transfer function and the third transfer function, specifically as shown in the following formula (3):
[0098] Sz = Fir1 / (1 - Fir3) …………… (3)
[0099] Wherein, Fir1 represents the first transfer function, and Fir3 represents the third transfer function.
[0100] In the embodiments of the present application, first, estimate the first transfer function between the audio signal to be played and the converted audio signal, and estimate the third transfer function between the audio signal to be played and the third noise signal. Then, based on the first transfer function and the third transfer function, estimate the SZ transfer function, effectively reducing the interference of the noise in the converted audio signal and the third noise signal on the estimation of the SZ transfer function, thereby improving the accuracy of the SZ transfer function estimation. Secondly, when both the feedback noise reduction channel and the audio echo filter are in the working state, estimate the SZ transfer function, so that both the audio echo to be played can be eliminated and the SZ transfer function can be accurately estimated.
[0101] Embodiment 4: Estimate the SZ transfer function based on the audio signal to be played, the converted audio signal, and the target audio signal.
[0102] The feedforward noise reduction filter 202 in the feedforward noise reduction channel 101 operates at the first sampling frequency f1, and the sampling frequencies of the audio signal to be played and the converted audio signal are both the second sampling frequency f2. The ratio of the first sampling frequency f1 to the second sampling frequency f2 is a positive integer greater than 1.
[0103] Filter and downsample the target audio signal through the low-pass filtering and downsampling module to obtain the fourth noise signal, and the sampling frequency of the fourth noise signal is the second sampling frequency f2.
[0104] Use the audio signal to be played as the input and the converted audio signal as the output to estimate the first transfer function.
[0105] Use the audio signal to be played as the input and the fourth noise signal as the output to estimate the fourth transfer function; that is, the fourth transfer function is the transfer function between the audio signal to be played and the fourth noise signal. The estimation method of the fourth noise signal can be adaptive iteration, such as least mean square, recursive least mean square, normalized least mean square, etc.; it can also be other time-domain, frequency-domain, Z-domain methods, etc.
[0106] Based on the first transfer function and the fourth transfer function, estimate the SZ transfer function, as specifically shown in the following formula (4):
[0107] Sz = Fir1 / Fir4 …………… (4)
[0108] Wherein, Fir1 represents the first transfer function, and Fir3 represents the fourth transfer function.
[0109] In the embodiments of the present application, first, the first transfer function between the audio signal to be played and the converted audio signal is estimated, and the fourth transfer function between the audio signal to be played and the fourth noise signal is estimated. Then, based on the first transfer function and the fourth transfer function, the SZ transfer function is estimated, effectively reducing the interference of the noise in the fourth noise signal on the estimation of the SZ transfer function, thereby improving the accuracy of the SZ transfer function estimation. Secondly, when both the feedback noise reduction channel and the audio echo filter are in the working state, the SZ transfer function is estimated, so that both the audio echo to be played can be eliminated and the SZ transfer function can be accurately estimated.
[0110] In the process of estimating the SZ transfer function described in the above Embodiment 1 to Embodiment 4, it is all implemented by software, that is, using the processor 104 to implement by writing a program. However, the echo cancellation of the audio signal to be played is implemented by the hardware audio echo filter 103, that is, the component of the audio signal to be played in the first noise signal is eliminated, so that the audio signal to be played heard by the user is not affected by the feedback noise reduction channel 102. To achieve this function, it is required that the audio echo filter 103 has a fixed low latency. Therefore, the audio echo filter 103 operates at the first sampling frequency f1 which is relatively higher than the second sampling frequency f2, and is implemented by hardware.
[0111] In some embodiments, when the transfer function of the audio echo filter 103 is the SZ transfer function, the echo cancellation of the audio signal to be played can be completely achieved. Therefore, the SZ transfer function can be obtained by using a tester or an artificial ear to normally wear the prototype for testing, and used as the transfer function of the audio echo filter 103. However, when the state (position, orientation, tightness, etc.) of the headphone relative to the ear changes, the SZ transfer function often changes. When different users wear the headphones, their SZ transfer functions will also be different. Therefore, when using a tester or an artificial ear to normally wear the prototype to test or debug the SZ transfer function and using this SZ transfer function as the transfer function of the audio echo filter 103, there is often a deviation from the SZ transfer function obtained by real-time estimation. Therefore, in the present application, the SZ transfer function is estimated at a lower frequency in a software manner (that is, the scheme described in any of the above embodiments) and used as the transfer function of the audio echo filter 103. Since the SZ transfer function is monitored in real time by software, low power consumption and resource saving can be achieved.
[0112] Based on the same technical concept, the embodiments of the present application provide an electronic device, and this computer device can be Figure 1 the active noise-canceling headphone shown in Figure 4 shown, including at least one processor 401 and a memory 402 connected to at least one processor. In the embodiments of the present application, the specific connection medium between the processor 401 and the memory 402 is not limited. Figure 4Take the example of the connection between the central processor 401 and the memory 402 through a bus. The bus can be divided into an address bus, a data bus, a control bus, etc.
[0113] In the embodiments of the present application, the memory 402 stores instructions executable by at least one processor 401. By executing the instructions stored in the memory 402, the at least one processor 401 can perform the above-mentioned active noise reduction process.
[0114] Among them, the processor 401 is the control center of the computer device, which can connect various parts of the computer device through various interfaces and lines. By running or executing the instructions stored in the memory 402 and calling the data stored in the memory 402, active noise reduction can be achieved. Optionally, the processor 401 may include one or more processing units. The processor 401 may integrate an application processor and a modem processor. Among them, the application processor mainly processes the operating system, user interface, application programs, etc., and the modem processor mainly processes wireless communication. It can be understood that the above-mentioned modem processor may not be integrated into the processor 401. In some embodiments, the processor 401 and the memory 402 can be implemented on the same chip. In some embodiments, they can also be separately implemented on independent chips.
[0115] The processor 401 can be a general-purpose processor, such as a central processing unit (CPU), a digital signal processor, an application specific integrated circuit (ASIC), a field programmable gate array or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, which can implement or execute the various methods, steps and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor can be a microprocessor or any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present application can be directly embodied as being executed by a hardware processor, or by a combination of hardware and software modules in the processor.
[0116] The memory 402, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules. The memory 402 can include at least one type of storage medium. For example, it can include flash memory, hard disks, multimedia cards, card-type memories, random access memory (RAM), static random access memory (SRAM), programmable read-only memory (PROM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), magnetic memories, magnetic disks, optical disks, and so on. The memory 402 is any other medium that can be used to carry or store the desired program code in the form of instructions or data structures and can be accessed by a computer device, but is not limited thereto. The memory 402 in the embodiments of the present application can also be a circuit or any other device capable of implementing a storage function, for storing program instructions and / or data.
[0117] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk memories, CD-ROMs, optical memories, etc.) that contain computer-usable program code.
[0118] The present invention is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present invention. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and the combination of flows and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processors of general-purpose computers, special-purpose computers, embedded processors, or other programmable data processing devices to generate a machine, such that the instructions executed by the processors of the computer device or other programmable data processing devices generate means for implementing the functions specified in Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.
[0119] These computer program instructions can also be stored in a computer-readable memory that can direct a computer device or other programmable data processing device to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction means that implements the functions specified in one or more processes and / or blocks Figure 1 in the process Figure 1 or processes and / or blocks
[0120] These computer program instructions can also be loaded onto a computer device or other programmable data processing device, such that a series of operational steps are performed on the computer device or other programmable device to produce a process implemented by the computer device, and thus the instructions executed on the computer device or other programmable device provide steps for implementing the functions specified in one or more processes and / or blocks Figure 1 in the process Figure 1 or processes and / or blocks
[0121] Although the preferred embodiments of the present invention have been described, additional changes and modifications can be made by those skilled in the art once they learn the basic inventive concept. Therefore, the appended claims are intended to be construed to include the preferred embodiments as well as all changes and modifications that fall within the scope of the present invention
[0122] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations
Claims
1. An active noise-canceling headphone, characterized in that, Including: A feedforward noise reduction channel, a feedback noise reduction channel, an audio echo filter, a processor, and a first superposition module; The audio echo filter is used to filter the to-be-played audio signal and output an audio echo signal; The feedback noise reduction channel is used to generate a reverse noise signal after echo cancellation using the audio echo signal; The processor is used to estimate the SZ transfer function, and when the change value of the SZ transfer function is greater than a preset threshold, trigger the feedforward noise reduction channel to start adaptive noise reduction and output a forward noise signal for noise reduction. The SZ transfer function refers to the transfer function between the input signal of the playback module in the active noise-canceling headphones and the feedback audio signal collected by the feedback noise reduction channel; The first superposition module is used to superpose the to-be-played audio signal, the reverse noise signal, and the forward noise signal and output a target audio signal.
2. The active noise-canceling earphone according to claim 1, wherein, The feedback noise reduction channel includes: a feedback acquisition and conversion module, a feedback noise reduction filter, and a second superposition module; The second superposition module is used to superpose the converted audio signal output by the feedback acquisition and conversion module and the audio echo signal and output a first noise signal; The feedback noise reduction filter is used to filter the first noise signal and output the reverse noise signal.
3. The active noise-canceling headphones according to claim 2, characterized in that, When the processor executes the estimation of the SZ transfer function, specifically: Estimate the SZ transfer function based on the to-be-played audio signal, the converted audio signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter; The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, and the sampling frequencies of the to-be-played audio signal and the converted audio signal are both the second sampling frequency. The ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
4. The active noise-canceling earphone according to claim 3, characterized in that, When the processor executes the estimation of the SZ transfer function based on the to-be-played audio signal, the converted audio signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, specifically: Estimate a first transfer function with the to-be-played audio signal as the input and the converted audio signal as the output; Estimate the SZ transfer function based on the first transfer function, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter.
5. The active noise-canceling earphone according to claim 2, wherein, When the processor executes the estimation of the SZ transfer function, specifically: Estimate the SZ transfer function based on the to-be-played audio signal, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter; The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, and the sampling frequency of the to-be-played audio signal is the second sampling frequency. The ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
6. The active noise-canceling earphone according to claim 5, characterized in that, When the processor executes the estimation of the SZ transfer function based on the to-be-played audio signal, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, specifically: Filter and downsample the first noise signal through a low-pass filtering and downsampling module to obtain a second noise signal, and the sampling frequency corresponding to the second noise signal is a second sampling frequency; Estimate a second transfer function with the to-be-broadcast audio signal as the input and the second noise signal as the output; Estimate the SZ transfer function based on the second transfer function, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter; 7. The active noise-canceling earphone according to claim 2, wherein When the processor executes the estimation of the SZ transfer function, it is specifically used for: Estimate the SZ transfer function based on the to-be-broadcast audio signal, the converted audio signal, and the reverse noise signal; The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, the sampling frequencies corresponding to the to-be-broadcast audio signal and the converted audio signal are both second sampling frequencies, and the ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
8. The active noise-canceling headphones according to claim 7, wherein, When the processor executes the estimation of the SZ transfer function based on the to-be-broadcast audio signal, the first noise signal, the transfer function of the audio echo filter, and the transfer function of the feedback noise reduction filter, it is specifically used for: Filter and downsample the reverse noise signal through a low-pass filtering and downsampling module to obtain a third noise signal, and the sampling frequency corresponding to the third noise signal is a second sampling frequency; Estimate a first transfer function with the to-be-broadcast audio signal as the input and the converted audio signal as the output; Estimate a third transfer function with the to-be-broadcast audio signal as the input and the third noise signal as the output; Estimate the SZ transfer function based on the first transfer function and the third transfer function; 9. The active noise-canceling earphone according to claim 2, wherein When the processor executes the estimation of the SZ transfer function, it is specifically used for: Estimate the SZ transfer function based on the to-be-broadcast audio signal, the converted audio signal, and the target audio signal. The feedforward noise reduction filter in the feedforward noise reduction channel operates at a first sampling frequency, the sampling frequencies corresponding to the to-be-broadcast audio signal and the converted audio signal are both second sampling frequencies, and the ratio of the first sampling frequency to the second sampling frequency is a positive integer greater than 1.
10. The active noise-canceling earphone according to claim 9, wherein, When the processor executes the estimation of the SZ transfer function based on the to-be-broadcast audio signal, the converted audio signal, and the target audio signal, it is specifically used for: Filter and downsample the target audio signal through a low-pass filtering and downsampling module to obtain a fourth noise signal, and the sampling frequency corresponding to the fourth noise signal is a second sampling frequency; Estimate a first transfer function with the to-be-broadcast audio signal as the input and the converted audio signal as the output; Estimate a fourth transfer function with the to-be-broadcast audio signal as the input and the fourth noise signal as the output; Estimate the SZ transfer function based on the first transfer function and the fourth transfer function.