Active noise reduction integrated circuit, method and active noise reduction earphone using the same

Abstract

The present invention relates to an active noise reduction integrated circuit, an active noise reduction method and an active noise reduction earphone using the same. The active noise reduction method is applicable to a sound playing device having a plurality of active noise cancellation filter units. The active noise reduction method comprises: providing a first path to output a first path anti-noise signal, wherein the first path anti-noise signal is converted into a first signal through a physical channel, the first path comprising: a first active noise cancellation filter unit to generate a first anti-noise signal; providing a second path to receive an error signal containing a component of the first signal and output a second path anti-noise signal to the physical channel, the second path comprising: a second active noise cancellation filter unit to generate a second anti-noise signal, wherein the second anti-noise signal derives the second path anti-noise signal; removing the component of the first signal in the second path based on the first anti-noise signal; and playing based on the first path anti-noise signal and the second path anti-noise signal to eliminate noise.

Description

Technical Field

[0001] This invention relates to noise cancellation technology, and more particularly to an active noise cancellation integrated circuit, method, and active noise cancellation headphones that can stack multiple noise-canceling signals. Background Technology

[0002] Noise cancellation technology in headphones is generally divided into passive noise cancellation (PNC) and active noise cancellation (ANC). Passive noise cancellation mainly uses sound-insulating materials or special structures in the headphones to isolate noise as much as possible. This is typically found in in-ear or over-ear headphones; prolonged use can cause ear pain, and excessive sound pressure levels can even affect hearing. Active noise cancellation, on the other hand, incorporates a dedicated noise-canceling circuit within the headphones. This circuit typically uses an audio receiver (such as a miniature microphone) and a noise-canceling output chip to receive and analyze external noise and generate an anti-phase sound wave. The destructive interference of this sound wave cancels out the noise.

[0003] Furthermore, the aforementioned active noise cancellation is generally divided into feed-forward ANC, feedback ANC, and hybrid ANC. Feed-forward ANC places the noise-canceling microphone on the outside of the earphone, receives noise from outside the earphone, processes it through a digital signal processing integrated circuit, and generates an anti-noise signal. Feedback ANC places the noise-canceling microphone on the inside of the earphone, receives the sound signal from inside the ear canal, and feeds it back to the digital signal processing integrated circuit to generate an anti-noise signal. Hybrid ANC uses two or more noise-canceling microphones to receive noise, and generates multiple anti-noise signals through different digital signal processing integrated circuits. These sound wave signals are then superimposed to cancel out the noise. Summary of the Invention

[0004] Because antiphase sound waves are generated by multiple microphones at different locations and through different signal processing methods, the final observation point receives multiple antiphase sound waves superimposed, leading to overcompensation and making the human ear hear more noise. Therefore, how to mitigate or eliminate these deficiencies is a problem that needs to be solved.

[0005] This invention relates to an active noise-canceling headphone, which includes an audio conversion device and an active noise-canceling integrated circuit according to an embodiment of the invention. This active noise-canceling integrated circuit can stack multiple noise-canceling signals. The active noise-canceling integrated circuit includes: a first path for outputting a first path noise-canceling signal, wherein the first path noise-canceling signal is converted into a first signal via a physical channel; the first path includes: a first active noise cancellation filter unit for generating the first noise-canceling signal; a second path for receiving an error signal containing components of the first signal and outputting a second path noise-canceling signal to the physical channel; the second path includes: a second active noise cancellation filter unit for generating a second noise-canceling signal, wherein the second noise-canceling signal derives from the second path noise-canceling signal; and a first decoupling unit for removing components of the first signal from the second path based on the first noise-canceling signal.

[0006] The present invention also relates to an active noise cancellation method capable of stacking multiple noise-canceling signals and applicable to a sound playback device having multiple active noise cancellation filtering units. This active noise cancellation method includes: providing a first path and outputting a first path noise-canceling signal, wherein the first path noise-canceling signal is converted into a first signal via a physical channel; the first path includes a first active noise cancellation filtering unit for generating the first noise-canceling signal; providing a second path, receiving an error signal containing components of the first signal, and outputting a second path noise-canceling signal to the physical channel; the second path includes a second active noise cancellation filtering unit for generating a second noise-canceling signal, wherein the second noise-canceling signal derives from the second path noise-canceling signal; removing components of the first signal from the second path based on the first noise-canceling signal; and playing back based on the first path noise-canceling signal and the second path noise-canceling signal to eliminate noise.

[0007] The spirit of this invention lies in incorporating multiple active noise cancellation filter units within the active noise cancellation device (e.g., an active noise cancellation integrated circuit) of an active noise-canceling headphone. Furthermore, to address the redundant components generated by other active noise cancellation filter units due to the output signal of each active noise cancellation filter unit, these redundant components are eliminated through decoupling. Therefore, the noise cancellation signal output by the active noise cancellation device more closely matches the received noise, thereby effectively eliminating the noise.

[0008] Other advantages of the present invention will be explained in more detail below with reference to the accompanying drawings. Attached Figure Description

[0009] The accompanying drawings, which are provided to further illustrate this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application.

[0010] Figure 1 The illustration shows a schematic diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention.

[0011] Figure 2 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention.

[0012] Figure 3 The drawing is as follows Figure 2 Comparison of noise suppression results in the examples.

[0013] Figure 4 The diagram illustrates a block diagram of the iso-calibrated sampling time of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention.

[0014] Figure 5 The diagram illustrates a block diagram of the iso-calibrated sampling time of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention.

[0015] Figure 6 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention.

[0016] Figure 7 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone without good isolation, according to a preferred embodiment of the present invention.

[0017] Figure 8 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention.

[0018] Figure 9 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention.

[0019] Figure 10 The diagram illustrates a flowchart of an active noise reduction method according to a preferred embodiment of the present invention.

[0020] The symbols in the attached diagram are briefly explained as follows:

[0021] 101: Left wireless earphone; 102: Right wireless earphone; 103: Mobile device; 19: Earphone shell; 20: Active noise cancellation integrated circuit capable of stacking multiple noise-canceling signals; 21: Audio conversion device; 201: First microphone; 202: Second microphone; 203: First active noise cancellation filter unit; 204: Second active noise cancellation filter unit; 205, 72: Physical channels; 301: Noise; 302: Only the first active noise cancellation filter unit 203 is enabled (Feed) Noise suppression results for Forward (FF); 303: Noise suppression results with only the second active noise cancellation filter unit 204 (Feedback (FB) enabled); 304: Expected noise suppression results with both the first and second active noise cancellation filter units 203 and 204 (FF+FB) enabled; 305: Actual noise suppression results with both the first and second active noise cancellation filter units 203 and 204 (FF+FB) enabled; 40, 50, 60: First decoupling unit; 70, 80: Second decoupling unit; 401, 501: First channel Analog filters; 402, 503, 603: First adder circuit; 502, 601: Third active noise cancellation filter unit; 504, 604, 702: Second adder circuit; 601: Third active noise cancellation filter unit; 602, 701, 801: Second channel analog filter; 603: First adder circuit; 604, 702, 802: Second adder circuit; 71: Non-isolated headphones; 91: Third active noise cancellation filter unit; 90: Third decoupling unit; S1001~S1003: Each step of the active noise reduction method for stackable multiple noise-resistant signals according to a preferred embodiment of the present invention. Detailed Implementation

[0022] The embodiments of the present invention will be described below with reference to the accompanying drawings. In these drawings, the same reference numerals denote the same or similar components or method flows.

[0023] It must be understood that the words “comprising” and “including” used in this specification are used to indicate the presence of specific technical features, values, method steps, work processes, components and / or components, but do not preclude the addition of more technical features, values, method steps, work processes, components, components, or any combination thereof.

[0024] In this invention, terms such as "first," "second," and "third" are used to modify components in the claims and are not used to indicate a priority order, a precedence relationship, or that one component precedes another, or the chronological order of the execution of method steps. They are only used to distinguish components with the same name.

[0025] It's important to understand that when a component is described as "connected" or "coupled" to another component, it can be a direct connection or coupling to other components, and there may be intermediate components. Conversely, when a component is described as "directly connected" or "directly coupled" to another component, there are no intermediate components. Other words used to describe the relationship between components can be interpreted in a similar way, such as "between" versus "directly between," or "adjacent" versus "directly adjacent," and so on.

[0026] Figure 1 The illustration shows a schematic diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention. Please refer to... Figure 1 In this embodiment, a wireless earbud is used as an example. The wireless earbud is a pair of devices with wireless communication capabilities, including a left wireless earbud 101 and a right wireless earbud 102, without any physical connection between them. The mobile device 103 and the left wireless earbud 101, as well as the mobile device 103 and the right wireless earbud 102, can use wireless communication protocols to transmit user-carrying voice or music packets, such as Bluetooth's Advanced Audio Distribution Profile (A2DP) packets.

[0027] In other embodiments, other peer-to-peer (P2P) wireless communication protocols such as Wi-Fi Direct may also be used between the mobile device 103 and the left wireless earphone 101, and between the mobile device 103 and the right wireless earphone 102. This invention is not limited thereto.

[0028] In the above embodiments, although the active noise-canceling headphones are exemplified as wireless headphones, those skilled in the art should know that active noise-canceling headphones can also be exemplified as wired headphones, and the present invention is not limited thereto.

[0029] Figure 2 This diagram illustrates the sampled-time block diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention. In this embodiment, the active noise-canceling headphone is an in-ear headphone. Please refer to... Figure 2The active noise-canceling headphones include an active noise-canceling integrated circuit 20 and an audio conversion device 21. In this embodiment, the audio conversion device 21 includes a first microphone 201, a second microphone 202, and a speaker (not shown). In this embodiment, for ease of explanation, a dashed outline is used as an example, representing the headphone housing 19. The first microphone 201 is outside the dashed line, indicating that it is positioned outside the ear canal to receive noise from outside the ear canal, while the second microphone 202 is inside the dashed line, indicating that it is positioned inside the ear canal. This dashed outline will be used in the following embodiments; however, this dashed line is not intended to limit the arrangement of the components of the invention.

[0030] The first microphone 201 is located on the outside of the earphone housing 19 and is mainly used to receive external noise signals from the earbud-type headphones. The external noise signal captured by the first microphone 201 is converted into an electrical signal after orientation and analog-to-digital conversion, and then input to the active noise cancellation integrated circuit 20. The first microphone 201 can be referred to as a reference microphone.

[0031] The second microphone 202 is disposed inside the earphone housing 19, between the earphone housing 19 and the eardrum, and is mainly used to receive noise and echoes inside the user's ear canal, i.e., ear canal echoes. The earphone housing 19 is used to provide passive noise cancellation. For example, the earphone housing 19 includes earphone sound-insulating material. More specifically, the second microphone 202 is used to receive sound signals inside the user's ear canal. The sound signals captured by the second microphone 202 are converted into electrical signals and input to the second active noise cancellation filter unit 204. The second microphone 202 may be referred to as an error microphone.

[0032] The active noise cancellation integrated circuit 20 generates an anti-noise electrical signal based on electrical signals acquired through the first microphone 201 and the second microphone 202. The digital anti-noise electrical signal is converted into an anti-noise signal via, for example, a digital-to-analog converter, a reconstruction filter, a power amplifier, and a speaker. For analysis, the aforementioned transmission will be presented as a transfer function. In short, the anti-noise electrical signal is converted into an anti-noise signal via the aforementioned transmission transfer function. Accordingly, to evaluate the aforementioned transmission transfer function, it is necessary to consider both the anti-noise electrical signal and the anti-noise signal.

[0033] However, in practice, the noise immunity signal cannot be directly obtained. A possible alternative is to receive the noise immunity signal through a second microphone 202 in the absence of external noise signals and convert the noise immunity signal into another electrical signal in analog form. This other electrical signal is then converted into a digital electrical signal, for example, through sequential transmission via a preamplifier, an anti-aliasing filter, and an analog-to-digital converter. This digital signal replaces the noise immunity signal in evaluating the transfer function.

[0034] Although the transfer function obtained in the alternative approach involves not only the transmission from the active noise cancellation integrated circuit 20 to the input of the second microphone 202, but also the transmission from the output of the second microphone 202 to the active noise cancellation integrated circuit 20, for the sake of simplicity, this transfer function can be used to represent the transmission from the active noise cancellation integrated circuit 20 to the input of the second microphone 202, which is represented here by physical channel 205. It should be noted that physical channel 205 includes the aforementioned speaker. In short, the noise-canceling electrical signal output by the active noise cancellation integrated circuit 20 is converted into a noise-canceling signal via the aforementioned physical channel 205.

[0035] On the other hand, external noise signals enter the inner side of the earphone housing 19 from the outside and finally reach the second microphone 202. This transmission is the primary path, not shown. For analysis purposes, the primary path will be represented by a transfer function. In short, the external noise signal is converted into a residual noise signal via the transfer function of the primary path. Therefore, to evaluate the transfer function of the primary path, both the external noise signal and the residual noise signal must be considered.

[0036] However, in practice, it is not possible to directly obtain both the external noise signal and the residual noise signal. One possible alternative is to receive the external noise signal via a first microphone 201 and convert it into an analog electrical signal. This additional electrical signal is then converted into a digital electrical signal, for example, through a preamplifier, an anti-aliasing filter, and an analog-to-digital converter. This digital signal replaces the external noise signal in evaluating the transfer function of the main path. Alternatively, the residual noise signal can be received via a second microphone 202 when the active noise cancellation integrated circuit 20 is disabled, and converted into an analog electrical signal. This additional electrical signal is also converted into a digital electrical signal, for example, through a preamplifier, an anti-aliasing filter, and an analog-to-digital converter. This digital signal replaces the residual noise signal in evaluating the transfer function of the main path.

[0037] In actual operation of active noise-canceling headphones (that is, when the active noise-canceling integrated circuit 20 is enabled), the anti-noise signal interferes with the residual noise signal to achieve the effect of active noise cancellation.

[0038] The active noise reduction integrated circuit 20 includes a first path and a second path.

[0039] The first path receives the output signal from the first microphone 201 and outputs a first path noise reduction signal to the physical channel 205. The first path noise reduction signal is converted into a first signal for noise cancellation by the physical channel 205.

[0040] The second path receives the output signal from the second microphone 202 and outputs a second path noise reduction signal to the physical channel 205. The second path noise reduction signal is converted into a second signal for noise cancellation by the physical channel 205.

[0041] The first path includes a first active noise cancellation filter unit 203. More specifically, the first path starts from the output of the first microphone 201, passes through the first active noise cancellation filter unit 203, and ends at the input of the physical channel 205.

[0042] The second path includes a second active noise cancellation filter unit 204. More specifically, the second path starts from the output of the second microphone 202, passes through the second active noise cancellation filter unit 204, and ends at the input of the physical channel 205.

[0043] exist Figure 2 In this embodiment, the first active noise cancellation filtering unit 203 filters the electrical signal output from the first microphone 201 to generate a first anti-noise signal y'1(n). The first anti-noise signal y'1(n) serves as the first path anti-noise signal in this embodiment. The weights of the first active noise cancellation filtering unit 203 are... Figure 2 The first active noise cancellation filter unit 203 can be implemented in various ways, such as using general-purpose hardware (e.g., microcontroller unit, digital signal processor, single processor, multiprocessor with parallel processing capabilities, graphics processor or other processor with computing capabilities), and providing active noise cancellation filtering functionality when executing software and / or firmware instructions.

[0044] The second active noise cancellation filtering unit 204 filters the electrical signal output from the second microphone 202 to generate a second anti-noise signal y'2(n). In this embodiment, the second anti-noise signal y'2(n) serves as the second path anti-noise signal. The weights of the second active noise cancellation filtering unit 204 are... Figure 2 The second active noise cancellation filter unit 204 can be implemented in various ways, such as using general-purpose hardware (e.g., microcontroller unit, digital signal processor, single processor, multiprocessor with parallel processing capabilities, graphics processor or other processor with computing capabilities), and providing active noise cancellation filtering functionality when executing software and / or firmware instructions.

[0045] In this embodiment, the first noise-resistant signal y'1(n) and the second noise-resistant signal y'2(n) are each input to the physical channel 205. However, the present invention is not limited thereto. In some embodiments, the first noise-resistant signal y'1(n) and the second noise-resistant signal y'2(n) can be added in the digital domain, and the summed noise-resistant signal is input to the physical channel 205.

[0046] The audio conversion device 21 converts the first noise-canceling signal y'1(n) and the second noise-canceling signal y'2(n) into an audio signal via the physical channel 205, and synthesizes them into a noise-canceling signal (i.e., the aforementioned noise-canceling signal). When this noise-canceling signal is actually transmitted through the ear canal, echo interference will occur due to the reflection and attenuation of sound waves within the ear canal. In other words, the noise-canceling signal will reach the user's ear and the second microphone 202 through a physical channel in a real environment.

[0047] In this embodiment, the active noise cancellation device (active noise cancellation integrated circuit) 20, which can stack multiple noise cancellation signals, is, for example, a dual noise cancellation system, that is, it has two active noise cancellation filter units 203 and 204, which can output two noise cancellation signals accordingly. The mutual interference of the two noise cancellation signals is generally expected to achieve a further noise suppression effect. However, this is not actually the case, as detailed in the following description... Figure 3 Please refer to this. Figure 3 , Figure 3 The drawing is as follows Figure 2 Comparison of noise suppression results in the examples.

[0048] like Figure 3 As shown, the vertical axis represents the magnitude and the horizontal axis represents the frequency. Label 301 indicates noise; label 302 indicates the noise suppression result when only the first active noise cancellation filter unit 203 (feedforward, FF) is enabled; label 303 indicates the noise suppression result when only the second active noise cancellation filter unit 204 (feedback, FB) is enabled; label 304 indicates the expected noise suppression result when both the first and second active noise cancellation filter units 203 and 204 (FF+FB) are enabled; and label 305 indicates the actual noise suppression result when both the first and second active noise cancellation filter units 203 and 204 (FF+FB) are enabled. Comparing labels 304 and 305, it can be observed that labels 304 and 305 overlap at relatively low frequencies but not at relatively high frequencies. That is, at relatively high frequencies, the actual noise suppression result cannot achieve the expected noise suppression result.

[0049] To explain why this result occurred, refer back to... Figure 2d(n) represents the main noise signal originating from external noise signals, i.e., the aforementioned residual noise signal; y1(n) represents the first signal related to the first anti-noise signal y'1(n) output by the first active noise cancellation filter unit 203, where the first signal y1(n) is an audio signal; y2(n) represents the second signal related to the second anti-noise signal y'2(n) output by the second active noise cancellation filter unit 204, where the second signal y2(n) is an audio signal; and e(n) represents the error signal output by the second microphone 202. It should be noted that, for the sake of simplicity, the process of converting the audio signal into a digital electrical signal is omitted.

[0050] The error signal e(n) output by the second microphone 202 can be regarded as a digital electrical signal.

[0051] Without any active noise cancellation filtering units 203 and 204 activated, the second microphone 202 only captures the main noise signal d(n) as the error signal e(n), that is, e(n) = d(n). With the second active noise cancellation filtering unit 204 activated, the second microphone 202 captures both the main noise signal d(n) and the second signal y2(n) as the error signal e(n), that is, e(n) = d(n) + y2(n). The main noise signal d(n) and the second signal y2(n) are added together by the adder unit 206. It should be noted that the adder unit 206 shown in the figure is not a physical component, but is only for ease of understanding in the analysis. Similarly, when the active noise cancellation filter units 203 and 204 are turned on, the second microphone 202 captures the main noise signal d(n), the first signal y1(n) and the second signal y2(n) as the error signal e(n), that is, e(n) = d(n) + y1(n) + y2(n).

[0052] The second active noise cancellation filter unit 204 generates a second noise-resistant signal y'2(n) based on the error signal e(n) received by the second microphone 202. However, in this case, based on the equation e(n) = d(n) + y1(n) + y2(n), it can be seen that the error signal e(n) captured by the second microphone 202 has been interfered with by the first signal y1(n), making the second noise-resistant signal y'2(n) generated by the second active noise cancellation filter unit 204 ineffective, thus leading to problems such as over-processing of noise. In short, every sound received by the second microphone 202 contains the first signal y1(n), causing the actual noise to be neither properly suppressed nor over-compensated.

[0053] In the above embodiments, the type of headphones is in-ear headphones. That is, the headphone shell 19 is considered to effectively block the second signal y2(n) from propagating to the outside of the in-ear headphones, so that the first microphone 201 cannot receive the second signal y2(n). If the headphones are open-back and the headphone shell 19 is considered not to effectively block the second signal y2(n) from propagating to the outside of the headphones, the first microphone 201 will receive the second signal y2(n), which will lead to more severe mutual interference, and may result in more severe noise than with only a single noise cancellation system.

[0054] To solve the problems mentioned above, one possible approach is to remove the first signal y1(n) from the error signal e(n) based on the mathematical principles of linear systems, as in this case. Figure 4 Examples of implementations.

[0055] Figure 4 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention. Figure 4 The active noise-canceling headphones employ a composite noise-canceling architecture. (Refer to...) Figure 4 , Figure 4 Active noise-canceling headphones are similar to Figure 2 The difference between active noise-canceling headphones is that... Figure 4 The stackable multiple noise cancellation signal active noise reduction device 20 further includes a first decoupling unit 40. The first decoupling unit 40 is used to remove the first signal y1(n) in the error signal e(n) captured by the second microphone 202 by means of electrical signal processing. In some embodiments, the first decoupling unit 40 is implemented by a digital signal processor. In this embodiment, the first path starts from the output of the first microphone 201, passes through the first active noise cancellation filter unit 203, and goes to the input of the physical channel 205; and the second path starts from the output of the second microphone 202, passes through the second active noise cancellation filter unit 204, and goes to the input of the physical channel 205.

[0056] The first decoupling unit 40 includes a first-channel analog filter 401 and a first adder circuit 402. The first-channel analog filter 401 is, for example, a transfer function simulating the physical channel 205, which is represented by a Z-domain transfer function. In other words, simulated physical channels It is essentially the same as the physical channel S(z)205.

[0057] Physical channel 205 represents the transmission of an ANC filter (e.g., a first active noise cancellation filter unit 203 or a second active noise cancellation filter unit 204) to a second microphone 202, thereby analyzing the transformation of the electrical signal output by the ANC filter after the transmission, where the simulation result is represented by a transfer function S(z). In some possible implementations, external noise sources are removed, and the transfer function S(z) is evaluated based on the electrical signal output by the ANC filter and based on the error signal e(n) obtained via the second microphone 202, where, since there are no external noise sources, there is no main noise signal d(n). Therefore, the error signal e(n) is substantially the same as at least one of the first signal y1(n) and the second signal y2(n) or the sum thereof, depending on the activation status of the first active noise cancellation filter unit 203 and the second active noise cancellation filter unit 204.

[0058] The first channel analog filter 401 receives the first anti-noise signal y1(n) output by the first active noise cancellation filter unit 203 to generate the first decoupling signal. In the simulated physical channel In essence, the simulation of the physical channel S(z)205 is the same as that of the physical channel. The input signal of the physical channel S(z)205 is the first anti-noise signal y'1(n), and the first decoupling signal output by the simulated physical channel is... This is essentially equivalent to the first signal y1(n) output by the physical channel S(z)205. Next, the first input port of the first adder circuit 402 receives the first decoupling signal. The second input port of the first adder circuit 402 receives the error signal e(n). Then, the first adder circuit 402 decouples the first decoupled signal from the error signal e(n). The first signal y1(n) is subtracted (considered as subtracting the first signal y1(n)) and provided to the second active noise cancellation filter unit 204. The error signal e(n) received by the second active noise cancellation filter unit 204 is then essentially equal to d(n) + y2(n), and no longer contains the first signal y1(n). Therefore, the noise suppression effect is significantly improved. In this embodiment, the first decoupling unit 40 subtracts the first signal y1(n) of the error signal e(n) during the signal processing of the circuit to solve the above-mentioned overcompensation problem.

[0059] Figure 5 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention. Figure 5 The active noise-canceling headphones employ a composite noise-canceling architecture. Please refer to [link / reference]. Figure 2 as well as Figure 5In this embodiment, the active noise reduction device 20, which can stack multiple noise-resistant signals, also adds a first decoupling unit 50 to remove the first signal y1(n) by electrical signal processing.

[0060] In this embodiment, the first decoupling unit 50 includes a first channel analog filter 501, a third active noise cancellation filter unit 502, a first adder circuit 503, and a second adder circuit 504.

[0061] The first channel analog filter 501 has the same function as... Figure 4 The first channel analog filter 401 in this embodiment is used to simulate the physical channel 205, receive the first noise-resistant signal y'1(n), and generate the first decoupling signal. The first noise reduction signal y'1(n) is an external noise signal received by the first microphone 201, which is obtained by the first active noise cancellation filter unit 203 after sampling digital-to-analog conversion.

[0062] In this embodiment, the transfer function of the third active noise cancellation filter unit 502 is, for example, the same as the transfer function of the second active noise cancellation filter unit 204, therefore the weight of the third active noise cancellation filter unit 502 is also W2. That is, the filtering operation of the third active noise cancellation filter unit 502 is the same as the filtering operation of the second active noise cancellation filter unit 204. Therefore, when the first decoupling signal... When the input is given to the third active noise cancellation filter unit 502, the third noise reduction signal output by the third active noise cancellation filter unit 502 can be expressed as:

[0063] The second active noise cancellation filter unit 204 receives the error signal output by the second microphone 202, labeled as d(n)+y1(n)+y2(n). Therefore, the signal output by the second active noise cancellation filter unit 204 is labeled as [d(n)+y1(n)+y2(n)]W2.

[0064] The first input port of the first adder circuit 503 receives the third noise suppression signal. The second input port of the first adder circuit 503 receives the second anti-noise signal [d(n)+y1(n)+y2(n)]W2. Because Essentially equivalent to y1(n), the first adder circuit 503 subtracts the two signals, and the output is approximately [d(n) + y2(n)]W2. This [d(n) + y2(n)]W2 removes the component of y1(n). Furthermore, the main noise signal d(n) in the output [d(n) + y2(n)]W2 is negligible. Therefore, the output [d(n) + y2(n)]W2 can be further simplified to the expression [y2(n)]W2, which is represented here as y'2(n). Thus, although the second active noise cancellation filter unit 204 is interfered with by the first signal y1(n), the interference is effectively eliminated by the third active noise cancellation filter unit 502 and the first adder circuit 503.

[0065] The first input port of the second adder circuit 504 is coupled to the output port of the first adder circuit 503 to receive the output y'2(n). The second input port of the second adder circuit 504 receives the first noise reduction signal y'1(n). The two signals are added together to obtain the electrical signal component y'1(n) + y'2(n) of the noise cancellation signal. In some embodiments, the second adder circuit 504 may be omitted.

[0066] The above Figure 5 The embodiment adopts the same as Figure 4 Different decoupling methods can all eliminate redundant components of the first signal y1(n). Another embodiment is presented below, which can also eliminate redundant components of the first signal y1(n), enabling those skilled in the art to implement this invention.

[0067] Figure 6 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention. Figure 6 The active noise-canceling headphones employ a composite noise-canceling architecture. Unlike... Figure 5 The embodiment processes the error signal e(n) provided by the second microphone 202 to achieve decoupling. Figure 6 In this embodiment, the signal provided by the first microphone 201 is processed to achieve the effect of decoupling, as detailed below.

[0068] The first decoupling unit 60 includes a third active noise cancellation filter unit 601, a channel analog filter 602, a first adder circuit 603, and a second adder circuit 604, wherein the channel analog filter 602 has the same function as... Figure 4 The first channel analog filter 401 in the embodiment.

[0069] The operation of the third active noise cancellation filter unit 601 is the same as that of the second active noise cancellation filter unit 204. The main difference is that this third active noise cancellation filter unit 601 receives the first anti-noise signal y'1(n) output by the first active noise cancellation filter unit 203 and outputs the third anti-noise signal y'1(n)W2. Then, it is processed by the first channel analog filter 602 to generate the first decoupling signal.

[0070] Furthermore, the operation of the third active noise cancellation filter unit 601 is similar to Figure 5 The third active noise cancellation filter unit 502 differs in that, in Figure 5 In one embodiment, the first noise-resistant signal y'1(n) is first processed by the first channel analog filter 501, and then by the third active noise cancellation filter unit 502. In this embodiment, however, the first noise-resistant signal y'1(n) is first processed by the third active noise cancellation filter unit 601, and then by the channel analog filter 602. According to the mathematical principles of linear systems, the different configuration order does not substantially change the result, and will not be elaborated upon here. Accordingly, in some embodiments, the first noise-resistant signal y'1(n) can be configured to be processed by the channel analog filter 602 first, and then by the third active noise cancellation filter unit 601.

[0071] The first input port of the first adder circuit 603 receives the first decoupling signal. The second input port of the first adder circuit 603 receives the first anti-noise signal y'1(n), subtracts the two, and then the second adder circuit 604 interferes with the signals on the path of the second active noise cancellation filter unit 204 to eliminate the redundant first signal y1(n) component in the anti-noise signal [d(n)+y1(n)+y2(n)]W2 output by the second active noise cancellation filter unit 204. Specifically, the signal output by the first adder circuit 603... Ingredients The component [y1(n)W2] in the noise-canceling signal [d(n)+y1(n)+y2(n)]W2 output by the second active noise cancellation filter unit 204 is used to eliminate the noise component [y1(n)W2]. Furthermore, the main noise signal d(n) in the noise-canceling signal [d(n)+y1(n)+y2(n)]W2 can be ignored. Therefore, the signal output by the second adder circuit 604 is [y2(n)W2+y'1(n)], which is further simplified to [y'2(n)+y'1(n)].

[0072] In the above embodiments, in-ear headphones are used as examples. Because in-ear headphones provide good isolation between the internal and external microphones, noise received by the internal microphone cannot be received by the external microphone. Therefore, in the above embodiments, echo noise cannot affect the first microphone. The following is an example without good isolation.

[0073] Figure 7 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone without good isolation, according to a preferred embodiment of the present invention. Figure 7 The active noise-canceling headphones employ a composite noise-canceling architecture. Please refer to [link / reference]. Figure 7 In this embodiment, the active noise-canceling headphones are semi-in-ear. The earpiece shell 19 of this type of active noise-canceling headphone cannot effectively block sound from the inside of the active noise-canceling headphone to the outside; therefore, the reverse noise from the echo inside the ear canal can also interfere with the external first microphone 201. Therefore, in addition to the first decoupling unit 40, the active noise-canceling device of the above-described active noise-canceling headphone system, which can stack multiple noise-canceling signals, further includes a second decoupling unit 70.

[0074] This technology is conceptually the same as the aforementioned embodiments. The first decoupling unit 40 generates a first decoupling signal based on the anti-noise signal output by the first active noise cancellation filter unit 203. Similarly, the second decoupling unit 70 generates a second decoupling signal based on the anti-noise signal output by the second active noise cancellation filter unit 204.

[0075] In this embodiment, the first decoupling unit 40 is similar to Figure 4 An embodiment includes a first-channel analog filter 401 and a first adder circuit 402. The first-channel analog filter 401 is substantially the same as the physical channel 205, and it receives the first anti-noise signal y'1(n) output by the first active noise cancellation filter unit 203 to generate a first decoupling signal. This first decoupling signal Essentially, it is almost equal to the first signal y1(n). The first error signal e2(n) received by the second microphone 202 is [d2(n) + y1(n) + y2(n)]. Next, the first input port of the first adder circuit 402 receives the first decoupling signal. The second input port of the first adder circuit 402 receives the first error signal e2(n). Therefore, the first decoupling signal... The y1(n) component of the first error signal e2(n) is subtracted and output to the second active noise cancellation filter unit 204. The signal e2'(n) received by the second active noise cancellation filter unit 204 is then essentially equal to d2(n) + y2(n). In other words, the second active noise cancellation filter unit 204 is no longer interfered with by the first signal y1(n) and can generate an effective anti-noise signal. (For ease of explanation...) Figure 7 In this embodiment, the transfer function of the physical channel 205 is represented as S1(z), and the transfer function of the first channel analog filter 401 is represented as...

[0076] On the other hand, since the earphone's structure in this embodiment is not isolated, the reverse noise from the echo inside the ear canal can also interfere with the external first microphone 201. This other physical channel 72 in the real environment is also represented by the Z-domain transfer function S2(z). In other words, the transfer function S2(z) of this second physical channel 72 represents the transmission between the active noise cancellation integrated circuit 20 and the input to the first microphone 201. Similarly, after the noise cancellation signals y'1(n) and y'2(n) output by the active noise cancellation device 20, which can stack multiple noise cancellation signals, are transmitted via the second physical channel 72, x1(n) represents the sound signal corresponding to the first noise cancellation signal y'1(n), and x2(n) represents the sound signal corresponding to the second noise cancellation signal y'2(n). Regarding the actual sound signal transmission, since signals x1(n) and x2(n) are transmitted from inside the ear canal to the first microphone 201, their channel response is different from the channel response inside the ear canal. Therefore, signals x1(n) and x2(n) are different from sound signals y1(n) and y2(n).

[0077] In addition to receiving signals x1(n) and x2(n), the first microphone 201 also receives an external noise signal d1(n). Accordingly, the first microphone 201 uses the external noise signal d1(n), signals x1(n), and x2(n) as a second error signal e1(n). Furthermore, the external noise signal d1(n) is converted into a main noise signal d2(n) after entering the active noise-canceling headphones. The main noise signal d2(n) is essentially equivalent to... Figure 2 The main noise signal d(n) in the example.

[0078] If the second error signal e1(n) is not processed, and the first active noise cancellation filter unit 203 receives the second error signal e1(n) containing the signal x2(n), it is similar to Figure 2The reason for this embodiment is that the first active noise cancellation filter unit 203 is interfered with by the signal x2(n), and therefore the generated anti-noise signal cannot effectively cancel the noise. Therefore, it is necessary to remove the signal x2(n) from the second error signal e1(n) so that the signal received by the first active noise cancellation filter unit 203 does not contain the signal x2(n).

[0079] Therefore, this embodiment proposes a second decoupling unit 70, including a second-channel analog filter 701 and a second adder circuit 702. Since the signal x2(n) is output by the physical channel 72, in order to effectively eliminate the signal x2(n) in the second error signal e1(n), the second-channel analog filter 701 needs to simulate the physical channel 72, rather than simulating the physical channel 205.

[0080] The second channel analog filter 701 receives the second anti-noise signal y'2(n) output by the second active noise cancellation filter unit 204 to generate the second decoupling signal. This second decoupling signal This is essentially almost equal to the signal x2(n). Next, the first input port of the second adder circuit 702 receives the second decoupling signal. The second input port of the second adder circuit 702 receives the second error signal e1(n). Therefore, the signal x2(n) component in the second error signal e1(n) is subtracted and output to the first active noise cancellation filter unit 203. The signal e1'(n) received by the first active noise cancellation filter unit 203 is then essentially equal to d1(n) + x1(n). The first active noise cancellation filter unit 203 is not affected by the signal x2(n), and thus the generated first anti-noise signal y'1(n) is effective.

[0081] In this embodiment, the first path starts from the output of the first microphone 201, passes through the first active noise cancellation filter unit 203, and reaches the input of physical channels 205 and 72. The second path starts from the output of the second microphone 202, passes through the second active noise cancellation filter unit 204, and reaches the input of physical channels 205 and 72. The noise-canceling signal of the first path is converted into a third signal x1(n) via the second physical channel 72. The noise-canceling signal of the second path is converted into a fourth signal x2(n) via the second physical channel 72. In other words, the first path receives a second error signal e1(n) containing the fourth signal x2(n), causing the first active noise cancellation filter unit 203 in the first path to be interfered with by the fourth signal x2(n). In this embodiment, the second decoupling unit 70 removes the component of the fourth signal x2(n) in the first path based on the second noise-canceling signal y'2(n).

[0082] In other embodiments, only a single microphone is used, but there are examples of dual noise-canceling systems. For example... Figure 8 As shown, Figure 8 The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone according to a preferred embodiment of the present invention. Figure 8 The embodiment of the active noise-canceling headphones employs a feedback noise-canceling architecture. Please refer to... Figure 8 In this embodiment, there is only a second microphone 202 (in-ear canal noise receiving microphone). However, in this embodiment, there is indeed a first active noise cancellation filter unit 203 and a second active noise cancellation filter unit 204.

[0083] Unlike Figure 7 In this embodiment, if the signal received by the first active noise cancellation filter unit 203 is not decoupled, that is, if the error signal e(n) is received directly without decoupling processing, the first active noise cancellation filter unit 203 will be interfered with by the second signal y2(n), instead of... Figure 7 The example signal x2(n). Therefore, in order to effectively eliminate the signal y2(n) in the error signal e(n), the channel analog filter 801 in the second decoupling unit 80 needs to simulate the physical channel 205, rather than the physical channel 72, to generate the second decoupling signal. Similarly, the second adder circuit 802 receives the second decoupling signal. The signal e1'(n) is compared with the error signal e(n), and the signal y2(n) component in the error signal e(n) is subtracted, and then output to the first active noise cancellation filter unit 203. The signal e1'(n) received by the first active noise cancellation filter unit 203 is essentially equal to d(n) + y1(n), so that the first active noise cancellation filter unit 203 will not be interfered with by the signal y2(n), thus generating the first anti-noise signal y'1(n) with effective noise.

[0084] In other words, please refer to Figure 7 and Figure 8 , Figure 7 and Figure 8 The embodiments employ almost the same elimination architecture, the only difference being Figure 8 Only the second microphone 202 is used. Since the method for eliminating redundant components is similar, it will not be described in detail here.

[0085] In this embodiment, the first path starts from the output of the second microphone 202, passes through the first active noise cancellation filter unit 203, and ends at the input of the physical channel 205. The second path starts from the output of the second microphone 202, passes through the second active noise cancellation filter unit 204, and ends at the input of the physical channel 205.

[0086] Figure 9The diagram illustrates the iso-calibrated sampling time block diagram of an active noise-canceling headphone with good isolation, according to a preferred embodiment of the present invention. Figure 9 The active noise-canceling headphones employ a composite noise-canceling architecture. Please refer to [the relevant documentation / reference]. Figure 9 as well as Figure 8 , Figure 9 and Figure 8 The difference lies in the addition of feedforward noise reduction, which means adding a first microphone 201 and a third active noise cancellation filter unit 91.

[0087] For the first active noise cancellation filter unit 203, if the signal received by the first active noise cancellation filter unit 203 is not decoupled, the first active noise cancellation filter unit 203 will be interfered with by signals y0(n) and y2(n). Therefore, the channel analog filter 901 and the adder circuit 902 in the third decoupling unit 90 are used to eliminate the interference of signal y0(n), and the second decoupling unit 80 is used to eliminate the interference of signal y2(n). The principle of interference elimination is the same as that in the aforementioned embodiments, and will not be repeated here.

[0088] For the second active noise cancellation filter unit 204, if the signal received by the second active noise cancellation filter unit 204 is not decoupled, the second active noise cancellation filter unit 204 will be interfered with by signals y0(n) and y1(n). Therefore, the channel analog filter 901 and the adder circuit 903 in the third decoupling unit 90 are used to eliminate the interference of signal y0(n), and the first decoupling unit 40 is used to eliminate the interference of signal y1(n). The principle of interference elimination is the same as that in the aforementioned embodiments, and will not be repeated here. In addition, in this embodiment, in order to simplify the wiring complexity in the component schematic diagram, Figure 9 The relative positions of the additive unit 206 and the second microphone 202 are plotted and Figure 8 The positions of the addition unit 206 and the second microphone 202 in the figure are swapped. However, those skilled in the art should be able to infer that the relative positions of the addition unit 206 and the second microphone 202 in the figure cannot be used to limit the component configuration of the present invention.

[0089] As described above, this embodiment further includes a third path, which starts from the output of the first microphone 201, passes through the third active noise cancellation filter unit 91, and ends at the input of the physical channel 205. The third noise reduction signal y'0(n) output by the third active noise cancellation filter unit 91 is, in this embodiment, for example, the third path noise reduction signal, and the third noise reduction signal y'0(n) is converted into a third signal y0(n) by the physical channel 205. Since both the first and second paths receive error signals e(n) containing the third signal y0(n), the third decoupling unit 90 proposed in this embodiment removes the component of the third signal y0(n) from the first and second paths based on the third noise reduction signal y'0(n).

[0090] To address the aforementioned problems, this invention proposes an active noise reduction method that can stack multiple noise-resistant signals. Figure 10 The flowchart illustrates an active noise reduction method for stackable multiple noise-resistant signals according to a preferred embodiment of the present invention. Please refer to... Figure 10 This active noise reduction method, which can stack multiple noise-resistant signals, includes the following steps:

[0091] Step S1001: Provide a first path and output a first path noise reduction signal, wherein the first path noise reduction signal is converted into a first signal via a physical channel. The first path includes: a first active noise cancellation filter unit for generating a first noise reduction signal; provide a second path, receive an error signal containing a component of the first signal, and output a second path noise reduction signal to the physical channel. The second path includes: a second active noise cancellation filter unit for generating a second noise reduction signal, wherein the second noise reduction signal derives from the second path noise reduction signal.

[0092] Step S1002: Remove the components of the first signal in the second path based on the first noise reduction signal. For example... Figure 4 As shown, by passing the first noise-reducing signal through the first channel analog filter 401, the component of the first signal y1(n) in the error signal e(n) received by the second active noise cancellation filter unit 204 is removed at the input of the second active noise cancellation filter unit 204. Furthermore, as... Figure 5 As shown, the first noise-reducing signal is passed through the first channel analog filter 501 and the third active noise cancellation filter unit 502 (this unit has the same transfer function as the second active noise cancellation filter unit 204) to generate a decoupling signal, and decoupling is performed at the output of the second active noise cancellation filter unit 204. Similarly, as Figure 6As shown, a decoupling signal is generated by passing the first noise-canceling signal through the audio channel analog filter 602 and the third active noise cancellation filter unit 601 (this unit has the same transfer function as the second active noise cancellation filter unit 204), and decoupling is performed after the output of the second active noise cancellation filter unit 204. In other words, as long as there are at least two active noise cancellation filter units, and the noise-canceling signals generated by the aforementioned active noise cancellation filter units are mutually coupled, a decoupling signal can be generated through one specific noise-canceling signal to eliminate the component of the specific noise-canceling signal in the paths of other active noise cancellation filter units. Thus, the present invention can eliminate the aforementioned mutual interference. Figure 7 , 8 Embodiments 9 and 9 are examples derived from this spirit. Therefore, this invention does not aim to... Figure 4 , 5 Limited to 6.

[0093] Step S1003: Play back based on the first path noise reduction signal and the second path noise reduction signal to eliminate noise.

[0094] In summary, the spirit of this invention lies in setting up multiple active noise cancellation filter units within the active noise cancellation device of an active noise-canceling headphone. The output signal of each active noise cancellation filter unit causes redundant components generated by other active noise cancellation filter units. These redundant components are eliminated through decoupling. Therefore, the signals output by the multiple active noise cancellation filter units can be appropriately stacked to match the real noise, resulting in a noise cancellation signal that better matches the received noise and more effectively cancels the noise.

[0095] Although Figures 1 to 9 It includes the elements described above, but does not preclude the use of other additional elements to achieve better technical effects without departing from the spirit of the invention. Furthermore, although... Figure 10 The flowchart describes the steps in a specified order. However, those skilled in the art can modify the order of these steps to achieve the same effect without violating the spirit of the invention. Therefore, the present invention is not limited to using only the order described above. Furthermore, those skilled in the art can integrate several steps into one step, or perform more steps sequentially or in parallel in addition to these steps, and the present invention is not limited thereto.

[0096] The above description is only a preferred embodiment of the present invention, but it is not intended to limit the scope of the present invention. Any person skilled in the art can make further improvements and changes on this basis without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope defined in the claims of this application.

Claims

1. An active noise reduction integrated circuit capable of stacking multiple noise-resistant signals, characterized in that, The active noise reduction integrated circuit includes: A first path outputs a first path noise-resistant signal, wherein the first path noise-resistant signal is converted into a first signal via a physical channel, and the first path includes: The first active noise cancellation filter unit is used to generate the first anti-noise signal; The second path receives an error signal containing components of the first signal and outputs a second path noise-resistant signal to the physical channel. The second path includes: A second active noise cancellation filter unit is used to generate a second anti-noise signal, wherein the second anti-noise signal derives from the second path anti-noise signal; and The first decoupling unit is used to remove the component of the first signal in the second path based on the first noise reduction signal.

2. The active noise reduction integrated circuit as described in claim 1, characterized in that, The first decoupling unit includes: A first-channel analog filter, used to simulate the physical channel, receives the first noise-resistant signal to generate a first decoupling signal; and The first adder circuit includes a first input port, a second input port, and an output port. The first input port of the first adder circuit receives the first decoupling signal, the second input port of the first adder circuit receives the error signal, and the output port of the first adder circuit is coupled to the second active noise cancellation filter unit.

3. The active noise reduction integrated circuit as described in claim 1, characterized in that, The first decoupling unit includes: A first-channel analog filter, used to simulate the physical channel, receives the first noise-resistant signal to generate a first decoupling signal; and The third active noise cancellation filter unit, wherein the filtering operation of the third active noise cancellation filter unit is the same as the filtering operation of the second active noise cancellation filter unit, wherein the third active noise cancellation filter unit receives the first decoupling signal and generates a third anti-noise signal; A first adder circuit includes a first input port, a second input port, and an output port, wherein the first input port of the first adder circuit receives the third noise-resistant signal, and the second input port of the first adder circuit receives the second noise-resistant signal; and The second adder circuit includes a first input port, a second input port, and an output port. The first input port of the second adder circuit is coupled to the output port of the first adder circuit. The second input port of the second adder circuit receives the first noise reduction signal. The first noise reduction signal, the second noise reduction signal, and the first decoupling signal are combined into a noise cancellation signal by superimposing the signals from the first adder circuit and the second adder circuit.

4. The active noise reduction integrated circuit as described in claim 1, characterized in that, The first decoupling unit includes: The third active noise cancellation filter unit, wherein the filtering operation of the third active noise cancellation filter unit is the same as the filtering operation of the second active noise cancellation filter unit, wherein the third active noise cancellation filter unit receives the first anti-noise signal and generates a third anti-noise signal; A first channel analog filter is used to simulate the physical channel and receive the third noise-resistant signal to generate a first decoupling signal; A first adder circuit includes a first input port, a second input port, and an output port, wherein the first input port of the first adder circuit receives the first decoupling signal, and the second input port of the first adder circuit receives the first noise reduction signal; and The second adder circuit includes a first input port, a second input port, and an output port. The first input port of the second adder circuit is coupled to the output port of the first adder circuit. The second input port of the second adder circuit receives the second noise reduction signal. The first noise reduction signal, the second noise reduction signal, and the first decoupling signal are combined into a noise cancellation signal by superimposing the signals from the first adder circuit and the second adder circuit.

5. The active noise reduction integrated circuit as described in claim 1, characterized in that, The physical channel is the first physical channel. The second path noise reduction signal is converted into a fourth signal via a second physical channel. Wherein, the error signal is the first error signal. The first path receives a second error signal containing components of the fourth signal. The active noise reduction integrated circuit further includes: The second decoupling unit is used to remove the component of the fourth signal in the first path based on the second noise reduction signal.

6. The active noise reduction integrated circuit as described in claim 1, characterized in that, The second path noise reduction signal is converted into a second signal via the physical channel, wherein the error signal further contains a component of the second signal, wherein the first path receives the error signal, and wherein the active noise reduction integrated circuit further comprises: The second decoupling unit is used to remove the component of the second signal in the first path based on the second noise reduction signal.

7. The active noise reduction integrated circuit as described in claim 6, characterized in that, The active noise reduction integrated circuit further includes: The third path outputs a third-path noise-resistant signal, wherein the third-path noise-resistant signal is converted into a third signal via the physical channel, and the error signal further contains components of the third signal. The third path includes: A third active noise cancellation filter unit is used to generate a third anti-noise signal; and The third decoupling unit is used to remove the component of the third signal in the second path based on the third noise reduction signal, and further to remove the component of the third signal in the first path based on the third noise reduction signal.

8. The active noise reduction integrated circuit as described in claim 6, characterized in that, The second decoupling unit includes: A second-channel analog filter, used to simulate the physical channel, receives the second noise-resistant signal to generate a second decoupling signal; and The second adder circuit includes a first input port, a second input port, and an output port. The first input port of the second adder circuit receives the second decoupling signal, the second input port of the second adder circuit receives the error signal, and the output port of the second adder circuit is coupled to the first active noise cancellation filter unit.

9. An active noise-canceling headphone, characterized in that, The active noise-canceling headphones include: The active noise reduction integrated circuit as described in any one of claims 1 to 8; and Audio conversion devices, including: A loudspeaker for playing based on the first path noise-reducing signal and the second path noise-reducing signal to eliminate noise, wherein the loudspeaker is part of the physical channel; and A microphone is used to receive noise from the ear canal echo and convert it into the error signal.

10. An active noise reduction method, capable of stacking multiple noise-resistant signals and applicable to sound playback devices with multiple active noise cancellation filtering units, characterized in that, The active noise reduction method includes: A first path is provided, and a first path noise reduction signal is output, wherein the first path noise reduction signal is converted into a first signal via a physical channel. The first path includes: a first active noise cancellation filter unit for generating the first noise reduction signal; A second path is provided to receive an error signal containing a component of the first signal and to output a second path noise reduction signal to the physical channel. The second path includes a second active noise cancellation filter unit for generating a second noise reduction signal, wherein the second noise reduction signal derives from the second path noise reduction signal. Based on the first noise reduction signal, remove the component of the first signal in the second path; and Playback is performed based on the first path noise reduction signal and the second path noise reduction signal to eliminate noise.

11. The active noise reduction method as described in claim 10, characterized in that, Removing components of the first signal from the second path based on the first noise-reducing signal includes: The first noise-resistant signal is converted into a decoupled signal according to the physical channel; and At the input of the second active noise cancellation filter unit, decoupling is performed by the decoupling signal to remove the component of the first signal in the second path.

12. The active noise reduction method as described in claim 10, characterized in that, Removing components of the first signal from the second path based on the first noise-reducing signal includes: Based on the physical channel and the transfer function of the second active noise cancellation filter unit, a decoupling signal is generated; and At the output of the second active noise cancellation filter unit, decoupling is performed by the decoupling signal to remove the component of the first signal in the second path.

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