Systems and methods for noise reduction using sub-band noise reduction techniques - Patents.com

Abstract

A noise reduction system is provided. The noise reduction system may include a subband noise sensor, multiple subband noise reduction modules, and an output module. The subband noise sensor may be configured to detect noise and generate multiple subband noise signals in response to the detected noise. Each of the multiple subband noise signals may have a characteristic subband of the frequency band of the noise. Each of the subband noise reduction modules may be configured to receive one of the subband noise signals from the subband noise sensor and generate a subband noise correction signal for reducing the received subband noise signal. The output module may be configured to receive the subband noise correction signal and output a noise correction signal for reducing noise based on the subband noise correction signal.

Description

[Technical field]

[0001] FIELD OF THE DISCLOSURE This disclosure relates generally to noise reduction, and more particularly to systems and methods for noise reduction using sub-band noise reduction techniques. [Background technology]

[0002] Noise reduction is often required to suppress noise (e.g., undesirable sounds that are unpleasant, loud, or disruptive to hear). Conventionally, noise may be passively reduced by, for example, removing (or partially removing) the source of the noise, blocking the transmission of the noise, and / or preventing the user's ears from hearing the noise, or any combination thereof. These noise reduction techniques may be passive and have low noise reduction effects under some conditions (e.g., when the noise has a low frequency below a threshold frequency). In recent years, active noise reduction (ANR) techniques have been adopted to actively reduce noise by generating a noise reduction signal (e.g., a signal having an anti-phase with respect to the noise to be reduced). Conventional ANR devices may utilize full-band noise reduction techniques that generate a single noise correction signal having a frequency band that covers the frequency band of the noise to suppress the noise. Sub-band decomposition techniques can be used for noise reduction to improve the noise reduction effect. Therefore, it is desirable to provide a system and method for noise reduction using sub-band noise reduction techniques.

[0003] A system for reduction of noise is provided. The system may include a subband noise sensor, a plurality of subband noise reduction modules, and an output module. The subband noise sensor may be configured to detect noise and generate a plurality of subband noise signals in response to the detected noise. Each of the subband noise signals may have a unique subband of the frequency band of the noise. Each of the subband noise reduction modules may be configured to receive one of the subband noise signals from the subband noise sensor and generate a subband noise correction signal for reducing the received subband noise signal. The output module may be configured to receive the subband noise correction signal and output a noise correction signal for reducing noise based on the subband noise correction signal. Summary of the Invention [Problem to be solved by the invention]

[0004] In some embodiments, the sub-band noise sensor can include an acoustoelectric transducer and a band splitting module. The acoustoelectric transducer can be configured to detect noise and convert the noise into an electrical signal. The band splitting module can be coupled to the acoustoelectric transducer and configured to split the electrical signal into sub-band noise signals.

[0005] In some embodiments, the band splitting module may include a plurality of bandpass filters, each of which may have a unique frequency response and may be configured to generate one of the sub-band noise signals.

[0006] In some embodiments, a first one of the bandpass filters may have a first frequency response and be configured to generate a first sub-band noise signal of the sub-band noise signals. A second one of the bandpass filters may have a second frequency response and be configured to generate a second sub-band noise signal of the sub-band noise signals. The second sub-band noise signal may be adjacent to the first sub-band noise signal of the sub-band noise signals in the frequency domain. The first and second frequency responses may intersect at a frequency point near at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

[0007] In some embodiments, the first frequency response of the first bandpass filter and the second frequency response of the second bandpass filter may have the same frequency bandwidth or different frequency bandwidths.

[0008] In some embodiments, the sub-band noise reduction module may be integrated into the band splitting module.

[0009] In some embodiments, the sub-band noise sensor may include a plurality of acoustoelectric transducers and a plurality of sampling modules. Each of the acoustoelectric transducers may have a unique frequency response and may be configured to generate a sub-band noise electrical signal by processing the noise. Each of the sampling modules may be configured to receive one of the sub-band noise electrical signals and sample the received sub-band noise electrical signal to generate one of the sub-band noise signals.

[0010] In some embodiments, the acoustoelectric transducer of the acoustoelectric transducer may include an acoustic channel component and a sensorineural component. The acoustic channel component may be configured to filter the noise to generate sub-band noise. The sensorineural component may be configured to convert the sub-band noise into a sub-band noise electrical signal.

[0011] In some embodiments, the acoustoelectric transducer of the acoustoelectric transducer may include a sensorineural component that may be configured to convert noise into a sub-band noise electrical signal.

[0012] In some embodiments, a first one of the acoustoelectric transducers may be configured to generate a subband noise electrical signal having a first frequency response and corresponding to a first subband noise signal of the subband noise signals. A second one of the acoustoelectric transducers may be configured to generate a subband noise electrical signal having a second frequency response and corresponding to a second subband noise signal of the subband noise signals. The second subband noise signal may be adjacent to the first subband noise signal of the subband noise signals in the frequency domain. The first and second frequency responses may intersect at a frequency point near at least one of a half-power point of the first frequency response or a half-power point of the second frequency response.

[0013] In some embodiments, the first frequency response of the first acoustoelectric transducer and the second frequency response of the second acoustoelectric transducer have the same frequency bandwidth or different frequency bandwidths.

[0014] In some embodiments, the frequency band of the sub-band noise signal generated by the sub-band noise sensor may cover the frequency band of the noise.

[0015] In some embodiments, at least one of the sub-band noise reduction modules may include a phase modulator and an amplitude modulator. The phase modulator may be configured to receive a corresponding sub-band noise signal and generate a phase modulated signal by modulating a phase of the corresponding sub-band noise signal. The amplitude modulator may be configured to receive the phase modulated signal from the phase modulator and generate a sub-band noise correction signal for reducing the corresponding sub-band noise signal by modulating an amplitude of the phase modulated signal.

[0016] In some embodiments, the phase modulation of the corresponding sub-band noise signal may include inverting the phase of the corresponding sub-band noise signal and, optionally, compensating for a phase shift of the corresponding sub-band noise signal in its transmission from the sub-band noise sensor to the phase modulator.

[0017] In some embodiments, at least one of the sub-band noise reduction modules may include an amplitude modulator and a phase modulator. The amplitude modulator may be configured to receive a corresponding sub-band noise signal and generate an amplitude modulated signal by modulating an amplitude of the corresponding sub-band noise signal. The phase modulator may be configured to receive the amplitude modulated signal from the amplitude modulator and generate a sub-band noise correction signal for reducing the corresponding sub-band noise signal by modulating a phase of the amplitude modulated signal.

[0018] In some embodiments, the phase modulation of the amplitude modulated signal may include inverting the phase of the amplitude modulated signal and, optionally, compensating for a phase shift of the corresponding sub-band noise signal in its transmission from the sub-band noise sensor to the phase modulator.

[0019] In some embodiments, the noise compensation signal may include a sub-band noise compensation signal. The output module may include a plurality of output units. Each of the output units may be configured to receive one of the sub-band noise compensation signals generated by the sub-band noise reduction module and output the received sub-band noise compensation signal.

[0020] In some embodiments, the output module may be configured to receive the sub-band noise compensation signals from the sub-band noise reduction modules. The output module may also be configured to combine the sub-band noise compensation signals to generate the noise compensation signal. The output module may also be configured to output the noise compensation signal.

[0021] In some embodiments, the noise may include ambient noise.

[0022] In some embodiments, the system may further include a residual noise sensor and a residual noise reduction module. The residual noise sensor may be configured to detect the residual noise and generate a residual noise signal in response to the detected residual noise. A distance between the residual noise sensor and the output module may be shorter than a distance between the sub-band noise sensor and the output module. The residual noise reduction module may be configured to receive the residual noise signal and generate a residual noise correction signal to reduce the residual noise.

[0023] In some embodiments, the output module may be further configured to receive the residual noise corrected signal and to output the residual noise corrected signal. The system may further include a second output module configured to receive the residual noise corrected signal and to output the residual noise corrected signal.

[0024] In some embodiments, the residual noise signal generated by the residual noise sensor may include a plurality of sub-band residual noise signals, and the residual noise correction signal may include a plurality of sub-band residual noise correction signals, each of which may be configured to reduce one of the sub-band residual noise signals.

[0025] In some embodiments, the system may include a residual noise sensor and a feedback module. The residual noise sensor may be configured to detect the residual noise and generate a residual noise signal in response to the detected residual noise. A distance between the residual noise sensor and the output module may be less than a distance between the sub-band noise sensor and the output module. The feedback module may be configured to adjust the sub-band noise reduction module in response to the residual noise.

[0026] In some embodiments, the sub-band noise sensor may be mounted near or within the output module, and the noise may include residual noise.

[0027] In some embodiments, the sub-band noise signal may be an analog signal, and the sub-band noise reduction module may include analog signal processing components.

[0028] In some embodiments, the sub-band noise signal may be a digital signal, and the sub-band noise reduction module may include digital signal processing components.

[0029] In some embodiments, the output module may include an electroacoustic transducer configured to convert the noise compensation signal into an audio signal and output the audio signal.

[0030] In some embodiments, the output module may include a signal processor and an electroacoustic transducer. The signal processor may be configured to process the noise compensation signal. The electroacoustic transducer may be configured to convert the processed noise compensation signal into an audio signal and output the audio signal.

[0031] Additional features are set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and the accompanying drawings, or may be learned by the practice or operation of the examples. The features of the disclosure may be realized and attained by practice or use of various aspects of the methods, instrumentalities, and combinations that are described in the detailed examples set forth below.

[0032] The present disclosure will be further described with respect to exemplary embodiments, which will be described in detail with reference to the drawings, which are non-limiting exemplary embodiments, and in which like reference numerals represent like structure throughout the several views of the drawings. [Brief description of the drawings]

[0033] [Figure 1A] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Figure 1B] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Diagram 2] 1 is a schematic diagram illustrating an exemplary noise reduction device according to some embodiments of the present disclosure. [Diagram 3] 1 is a schematic diagram illustrating an exemplary noise reduction device according to some embodiments of the present disclosure. [Figure 4] FIG. 2 is a schematic diagram illustrating an example sub-band noise sensor according to some embodiments of the present disclosure. [Figure 5A] 13 illustrates an example frequency response of a first bandpass filter and an example frequency response of a second bandpass filter of a band splitting module according to some embodiments of the present disclosure. [Figure 5B] 6 illustrates a frequency response of the first bandpass filter of FIG. 5 and another example frequency response of the second bandpass filter of FIG. 5 according to some embodiments of the present disclosure. [Figure 6] FIG. 2 is a schematic diagram illustrating an example sub-band noise sensor according to some embodiments of the present disclosure. [Figure 7] 1 is a schematic diagram illustrating an example sub-band noise reduction module according to some embodiments of the present disclosure. [Figure 8] 4A-4C are schematic diagrams illustrating example phase modulated signals according to some embodiments of the present disclosure. [Figure 9] 1 is a schematic diagram illustrating an example sub-band noise reduction module according to some embodiments of the present disclosure. [Figure 10] 1 is a schematic diagram illustrating an example sub-band noise sensor according to some embodiments of the present disclosure. [Figure 11] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Figure 12] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Figure 13] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Figure 14] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. [Figure 15] 1 is a schematic diagram illustrating an exemplary noise reduction system according to some embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] In the following detailed description, numerous specific details are set forth by way of example to provide a thorough understanding of the relevant disclosure. However, it will be apparent to those skilled in the art that the present disclosure may be practiced without such details. In other instances, well-known methods, procedures, systems, components, and / or circuits have been described at a relatively high level without detail to avoid unnecessarily obscuring aspects of the present disclosure. Various modifications to the disclosed embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. Thus, the present disclosure is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the claims.

[0035] It will be understood that the terms "system," "engine," "unit," "module," and / or "block" as used herein are one way of distinguishing between different components, elements, parts, sections, or assemblies at different levels in ascending order. However, the terms may be substituted by other expressions if they can accomplish the same purpose.

[0036] When a unit, engine, module, or block is referred to as "being," "connected," or "coupled" to another unit, engine, module, or block, it will be understood that the other units, engines, modules, or blocks may be directly adjacent, connected, coupled, or in communication with each other, or there may be intervening units, engines, modules, or blocks, unless the context clearly dictates otherwise. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0037] The terms used herein are for the purpose of describing specific examples and embodiments only and are not intended to be limiting. As used herein, the singular forms "a", "an" and "the" may be intended to include the plural unless the context clearly indicates otherwise. It will be further understood that the terms "include" and / or "comprise", as used in this disclosure, specify the presence of integers, devices, behaviors, described features, steps, elements, operations, and / or components, but do not preclude the presence or addition of one or more other integers, devices, behaviors, features, steps, elements, operations, components, and / or groups thereof.

[0038] Spatial and functional relationships between elements (e.g., between layers) are described using various terms, including "connected," "engaged," "interfaced," and "coupled." Unless a relationship between a first element and a second element is expressly described as "direct" when described in this disclosure, the relationship also includes a direct relationship in which there are no other intervening elements between the first element and the second element, and an indirect relationship in which there are one or more intervening elements (spatially or functionally) between the first element and the second element. In contrast, when an element is referred to as being "directly" connected, engaged, interfaced, or coupled to another element, there are no intervening elements. Furthermore, spatial and functional relationships between elements can be achieved in various ways. For example, a mechanical connection between two elements can include a welded connection, a keyed connection, a pin connection, an interference fit connection, etc., or any combination thereof. Other words used to describe relationships between elements should be interpreted similarly (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.).

[0039] An aspect of the present disclosure relates to a noise reduction system. The noise reduction system may include a subband noise sensor, a plurality of subband noise reduction modules, and an output module. The subband noise sensor may be configured to detect noise and generate a plurality of subband noise signals in response to the detected noise. Each of the plurality of subband noise signals may have a characteristic subband of a frequency band of the noise. Each of the subband noise reduction modules may be configured to receive one of the subband noise signals from the subband noise sensor and generate a subband noise correction signal for reducing the received subband noise signal. The output module may be configured to receive the subband noise correction signal and output the noise correction signal for reducing the noise.

[0040] According to some embodiments of the present disclosure, the system can reduce noise using a sub-band noise reduction technique that can perform noise reduction in multiple sub-bands of the frequency band of the noise. Compared with a full-band noise reduction technique that directly performs noise reduction on the entire frequency band of the noise, the sub-band noise reduction technique can improve the noise reduction effect. In some embodiments, the noise reduction system can be used in various scenarios to reduce various types of noise. For example, an audio broadcasting device may include an ambient noise reduction device for reducing ambient noise and a residual noise reduction device for reducing residual noise after suppressing the ambient noise, each or one of which may be realized by one or more components of the noise reduction system described above. By combining the ambient noise reduction device and the residual noise reduction device, unwanted sounds can be efficiently reduced, thereby improving the performance of the audio broadcasting device.

[0041] 1A is a schematic diagram illustrating an exemplary noise reduction system 100A according to some embodiments of the present disclosure. The noise reduction system 100A may be configured to reduce or cancel noise (e.g., harsh, loud, or undesirable sounds that interfere with listening). The noise reduction system 100A may be applied to various areas and / or devices, such as headphones (e.g., noise-canceling headphones, bone conduction headphones), mufflers, anti-snoring devices, etc., or any combination thereof. In some embodiments, the noise reduction system 100A may be an active noise reduction system that reduces noise by generating a noise reduction signal designed to reduce noise (e.g., a signal with an inverse phase to the noise).

[0042] As shown in FIG. 1A, the noise reduction system 100A may include an ambient noise reduction device 120, a residual noise reduction device 150, and an output module 170. In some embodiments, two or more components of the noise reduction system 100A may be connected and / or communicate with each other. For example, each of the ambient noise reduction device 120 and the residual noise reduction device 150 may be electrically connected to the output module 170. As used herein, a connection between two components may include a wireless connection, a wired connection, any other communication connection that may enable the transmission and / or reception of data, and / or any combination of these connections. The wireless connection may include, for example, a Bluetooth™ link, a Wi-Fi™ link, a WiMax™ link, a WLAN link, a ZigBee link, a mobile network link (e.g., 3G, 4G, 5G, etc.), or the like, or a combination thereof. Wired connections may include, for example, coaxial cable, communication cable (e.g., telecommunications cable), flexible cable, spiral cable, non-metallic sheathed cable, metallic sheathed cable, multi-core cable, twisted pair cable, ribbon cable, shielded cable, double stranded cable, optical fiber, electrical cable, optical cable, telephone line, etc., or any combination thereof.

[0043] The ambient noise reduction device 120 can be configured to reduce the ambient noise 110. For example, as shown in FIG. 1A, the ambient noise reduction device 120 can detect the ambient noise 110 and generate an ambient noise correction signal 130 to reduce the ambient noise 110. As used herein, the ambient noise 110 can refer to any sound other than a desired sound. For example, the ambient noise 110 can include background sounds (e.g., traffic noise, wind noise, water noise, voices coming from outside) that are present when a user wears an audio broadcasting device (e.g., earphones). The ambient noise 110 can be detected by the ambient noise reduction device 120 when the audio broadcasting device is playing audio (e.g., music) or not playing audio.

[0044] In some embodiments, the ambient noise reduction device 120 may be configured to reduce the ambient noise 110 according to a full-band noise reduction technique or a sub-band noise reduction technique. The full-band noise technique may refer to a technique for reducing noise by generating a single noise correction signal having a frequency band that covers the frequency band of the original noise. For example, the noise correction signal may be an analog or digital signal that is inverted in phase with respect to the noise. The sub-band noise technique may refer to a technique for reducing noise by generating multiple sub-band noise correction signals. Each of the sub-band noise correction signals may have a specific sub-band of the frequency band of the noise (i.e., a frequency band that is narrower than and within the frequency band of the noise) and may be configured to reduce a portion of the noise having the specific sub-band.

[0045] In some embodiments, the ambient noise reduction device 120 may include one or more components for implementing sub-band noise reduction techniques. For example, the ambient noise reduction device 120 may include a first sub-band noise sensor and a plurality of first sub-band noise reduction modules. The first sub-band noise sensor may be configured to detect the ambient noise 110 and generate a plurality of sub-band ambient noise signals. The frequency band of each sub-band ambient noise signal may be narrower than and within the frequency band of the ambient noise 110. The frequency bands of the different sub-band ambient noise signals may be different from each other. The first sub-band noise reduction module may be configured to generate a plurality of sub-band ambient noise correction signals based on the sub-band ambient noise signals. Each of the sub-band ambient noise correction signals may be an analog or digital signal used to reduce one of the sub-band ambient noise signals. The sub-band ambient noise correction signals may be processed (e.g., combined) to form or generate the ambient noise correction signal 130. In some embodiments, the ambient noise reduction device 120 may be implemented by a noise reduction device 200 having one or more components as shown in FIG.

[0046] As shown in FIG. 1, the ambient noise compensation signal 130 generated by the ambient noise reduction device 120 may be sent to the output module 170 for output. The output module 170 may include an electroacoustic transducer (e.g., a speaker, an audio player) that can convert an electrical signal into an audio signal to suppress the ambient noise 110. For example, the ambient noise compensation signal 130 may be a first composite signal of the sub-band ambient noise compensation signals. The output module 170 may directly convert the first composite signal into an audio signal for output. Alternatively, the output module 170 may include a signal processor and an electroacoustic transducer. The signal processor may be configured to process the first composite signal, and the electroacoustic transducer may be configured to convert the processed first composite signal into an audio signal for output. By way of example only, the first composite signal may be a digital signal. The signal processor may convert the first composite signal into a pulse width modulated (PWM) signal or an analog signal. Furthermore, the electroacoustic transducer may convert the PWM signal or the analog signal into sound for output. In some alternative embodiments, the signal processing unit of the output module 170 may be integrated into the ambient noise reduction device 120. The ambient noise reduction device 120 may process the first composite signal and send the processed first composite signal to the output module 170 for output.

[0047] In some embodiments, the ambient noise compensation signal 130 may include multiple sub-band ambient noise compensation signals as described above. The output module 170 may include multiple output units, each of which may include an electroacoustic transducer and optionally a signal processing unit. Each of the sub-band ambient noise compensation signals may be sent in parallel to one of the output units for output. The output of the sub-band ambient noise compensation signals by the output units may be performed similarly to the first synthesis signal of the sub-band ambient noise compensation signals by the output module 170, as described above.

[0048] The audio signal for reducing the ambient noise 110 output by the output module 170 may interface with the ambient noise 110, and the interference may suppress or partially suppress the ambient noise 110, as shown by the dotted line connecting the audio signal output by the output module 170 and the ambient noise 110 in FIG. 1A. In some embodiments, residual noise 140 may exist after the suppression of the ambient noise 110. The residual noise reduction device 150 may function as a feedback mechanism of the noise reduction system 100A for reducing the residual noise 140. For example, as shown in FIG. 1A, the residual noise reduction device 150 may detect the residual noise 140 and generate a residual noise correction signal 160 for reducing the residual noise 140.

[0049] In some embodiments, the residual noise reduction device 150 may be configured to reduce the residual noise 140 according to a full-band noise reduction technique or a sub-band noise reduction technique as described above. For example, the residual noise reduction device 150 may generate a single residual noise correction signal 160 having the same frequency band as the residual noise 140 but with an opposite phase to reduce the residual noise 140. As another example, the residual noise reduction device 150 may include one or more components for implementing a sub-band noise reduction technique, such as a second sub-band noise sensor and multiple second sub-band noise reduction modules. The distance between the second sub-band noise sensors may be shorter than the sensor of the ambient noise reduction device 120 for sensing the ambient noise 110 (e.g., the first sub-band noise sensor described above) so that the second sub-band noise sensor can detect the residual noise 140. In response to the residual noise 140, the second sub-band noise sensor may generate multiple sub-band residual noise signals, each of which may have a characteristic sub-band of the frequency band of the residual noise 140. Each of the second sub-band noise reduction modules may be configured to receive one of the sub-band residual noise signals from the second sub-band noise sensor and generate a sub-band residual noise correction signal for reducing the received sub-band residual noise signal. The sub-band residual noise correction signals may form or be processed (e.g., combined) to generate the residual noise correction signal 160. In some embodiments, the residual noise reduction device 150 may be implemented by a noise reduction device 200 having one or more components as shown in FIG. 2 and / or a residual noise reduction device 150C having one or more components as shown in FIG. 14.

[0050] The residual noise compensation signal 160 generated by the residual noise reduction device 150 may be sent to the output module 170 for output. The output of the residual noise compensation signal 160 may be implemented similarly to the output of the ambient noise compensation signal 130 described above. For example, the output module 170 may convert the residual noise compensation signal 160 into an audio signal for reducing the residual noise 140. As described above, the audio signal for reducing the residual noise 140 may be output together with the audio signal for reducing the ambient noise 110. The audio signal for reducing the residual noise 140 may be interfaced with the residual noise 140 as shown by the dotted line connecting the audio signal output by the output module 170 and the residual noise 140 in FIG. 1A. In some embodiments, the output module 170 may output the ambient noise compensation signal 130 and the residual noise reduction device 150 separately. Alternatively, the ambient noise compensation signal 130 and the residual noise compensation signal 160 may be combined to generate a second combined signal that may be further output by the output module 170 to suppress the ambient noise 110 and the residual noise 140.

[0051] In some alternative embodiments, instead of generating the residual noise compensation signal 160, the residual noise reduction device 150 may send a feedback signal to the ambient noise reduction device 120 according to the detected residual noise 140. For example, the feedback signal may be generated by a feedback module of the residual noise reduction device 150 and may include information about the residual noise 140. The ambient noise reduction device 120 may adjust another parameter related to the generation of the ambient noise compensation signal 130, and may thus generate an adjusted ambient noise compensation signal 130 to more efficiently suppress the ambient noise 110. As another example, the feedback signal may include instructions instructing the ambient noise reduction device 120 to adjust one or more parameters related to the generation of the ambient noise compensation signal 130. Further description regarding the feedback module and / or the adjustment of parameters related to the generation of the ambient noise compensation signal 130 may be found elsewhere in this disclosure. See, for example, FIG. 13 and its related description.

[0052] In some embodiments, the noise reduction system 100A may be applied to an audio broadcasting device. The components of the noise reduction system 100A may be mounted at any position of the audio broadcasting device. For example, the ambient noise reduction device 120 or a part thereof (e.g., a sensor for detecting the ambient noise 110) may be implemented outside the audio broadcasting device. The output module 170 may be implemented inside the audio broadcasting device. The output module 170 may be configured to function as an output component of the audio broadcasting device to output the noise correction signal and optionally output the desired audio (e.g., music). The residual noise reduction device 150 or a part thereof (e.g., a sensor for detecting the residual noise 140) may be mounted near or inside the output module 170.

[0053] 1B is a schematic diagram illustrating an exemplary noise reduction system 100B according to some embodiments of the present disclosure. The noise reduction system 100B may be similar to the noise reduction system 100A described in connection with FIG. 1A, except that the noise reduction system 100B may include an output module 170 and an additional output module 180. As shown in FIG. 1B, the output module 170 may be electrically connected to the ambient noise reduction device 120 to output the ambient noise correction signal 130. The output module 180 may be electrically connected to the residual noise reduction device 150 to output the residual noise correction signal 160.

[0054] It should be noted that the above description of the noise reduction systems 100A and 100B is intended to be illustrative and not limiting of the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the noise reduction system 100A and / or the noise reduction system 100B may include one or more additional components. Additionally or alternatively, one or more components of the noise reduction system 100A and / or the noise reduction system 100B described above may be omitted. For example, one of the ambient noise reduction device 120 and the residual noise reduction device 150 may be omitted. As another example, two or more components of the noise reduction system 100A and / or the noise reduction system 100B may be integrated into a single component. By way of example only, in noise reduction system 100B, output module 170 may be integrated into ambient noise reduction device 120 and / or output module 180 may be integrated into residual noise reduction device 150.

[0055] 2 is a schematic diagram illustrating an example noise reduction device 200 according to some embodiments of the present disclosure. The noise reduction device 200 may be configured to reduce noise 210 using sub-band noise reduction techniques, as described elsewhere in this disclosure (e.g., FIG. 1A and related discussion).

[0056] 2, the noise reduction device 200 may include a sub-band noise sensor 220, a plurality of sub-band noise reduction modules 230, and a synthesis module 240. The noise reduction device 200 may be coupled to an output module 170. The sub-band noise sensor 220 may be configured to detect noise 210 (e.g., ambient noise 110 or residual noise 140 as described in connection with FIG. 1) and generate a plurality of sub-band noise signals (e.g., sub-band noise signals S1-Sm) in response to the detected noise. "m" may be any positive integer greater than 1, such as 5, 10, 15, etc.

[0057] The noise 210 may be an audio signal in a certain frequency band. A sub-band noise signal may refer to a signal having a frequency band that is narrower than and within the frequency band of the noise 210. For example, the noise 210 may have a frequency band ranging from 10 Hz to 30,000 Hz. The frequency band of the sub-band noise signal may be 100 to 200 HZ, which is within the frequency band of the noise 210. In some embodiments, a combination of the frequency bands of the sub-band noise signals may cover the frequency band of the noise 210. Additionally or alternatively, at least two of the sub-band noise signals may have different frequency bands. Optionally, each of the sub-band noise signals may have a unique frequency band that is different from the frequency bands of the other sub-band noise signals. The different sub-band noise signals may have the same frequency bandwidth or different frequency bandwidths. In some embodiments, overlap between the frequency bands of a pair of adjacent sub-band noise signals in the frequency domain may be avoided to improve the noise reduction effect. As used herein, two sub-band noise signals whose center frequencies are adjacent to each other among the sub-band noise signals may be considered to be adjacent to each other in the frequency domain. Further description of the frequency bands of a pair of adjacent sub-band noise signals can be found elsewhere in this disclosure. For example, see Figures 5A and 5B and their related descriptions.

[0058] In some embodiments, the sub-band noise signal generated by the sub-band noise sensor 220 may be a digital signal or an analog signal. For illustrative purposes, unless otherwise specified or clear from the context, the present disclosure is described with reference to a sub-band noise signal in the form of a digital signal, and is not intended to limit the scope of the present disclosure. In some embodiments, the sub-band noise sensor 220 may include one or more components as shown in FIG. 4, which may be configured to convert the noise 210 into an electrical signal and split the electrical signal into sub-band noise signals. Alternatively, the sub-band noise sensor 220 may include one or more components as shown in FIG. 6, which may be configured to generate a plurality of sub-band noise electrical signals by processing the noise 210 and sample the sub-band noise electrical signals to generate the sub-band noise signals. Further description regarding the sub-band noise sensor 220 may be found elsewhere in this disclosure. See, for example, FIGS. 4-6 and their associated descriptions.

[0059] The subband noise reduction modules 230 may include a subband noise reduction module 230-1, a subband noise reduction module 230-2, ..., and a subband noise reduction module 230-m, as shown in Figure 2. In some embodiments, the count (or number) of the subband noise reduction modules 230 may be equal to the count (or number) of the subband noise signals generated by the subband noise sensor 220. Each of the subband noise reduction modules 230 may be configured to receive one of the subband noise signals from the subband noise sensor 220 and generate a subband noise correction signal for reducing the received subband noise signal. For example, as shown in Figure 2, the subband noise reduction module 230-i (where i is a positive integer less than or equal to m) may receive a subband noise signal S i from the subband noise sensor 220 and generate a subband noise correction signal C i for reducing the subband noise signal S i .

[0060] In some embodiments, the sub-band noise signals may be transmitted from the sub-band noise sensor 220 to the sub-band noise reduction module 230 via a parallel transmitter. Optionally, the sub-band noise signals may be transmitted via the transmitter according to a specific communication protocol for transmitting digital signals. Exemplary communication protocols may include AES3 (Audio Engineering Society), AES / EBU (European Broadcasting Union), EBU (European Broadcasting Union), ADAT (Automatic Data Storage and Forwarding Conversion), I2S (Inter-IC Sound), TDM (Time Division Multiplexing), MIDI (Musical Instrument Digital Interface), CobraNet, Ethernet AVB (Ethernet Audio / Video Bridge), Dante, ITU (International Telecommunication Union)-T G.728, ITU-T G.711, ITU-T G.722, ITU-T G.722.1, ITU-T G.722.1 Annex C, AAC (Advanced Audio Coding)-LD, etc., or combinations thereof. Digital signals include CD (Compact Disc), WAVE, AIFF (Audio Interchange File Format), MPEG (Moving Picture Experts Group)-1, MPEG-2, MPEG-3, MPEG-4, MIDI (Musical Instrument Digital Interface), WMA (Windows Media Audio), RealAudio, VQF (Transform-domain Weighted Interleave Vector Quantization), AMR (Adaptive Multi-Rate), APE, f L The sub-band noise signal may be transmitted in a predefined format, including Free Lossless Audio Codec (AC), Advanced Audio Coding (AAC), etc., or a combination thereof. In some alternative embodiments, the sub-band noise signal may be processed into a single channel signal, for example using frequency division multiplexing techniques, and sent to the sub-band noise reduction module 230.

[0061] In some embodiments, the subband noise reduction module 230-i may perform phase modulation and / or amplitude modulation on the subband noise signal S i to generate a corresponding subband noise correction signal C i. In some embodiments, the phase modulation and amplitude modulation may be performed sequentially or simultaneously on the subband noise signal S i. For example, the subband noise reduction module 230-i may first perform phase modulation on the subband noise signal S i to generate a phase-modulated signal, and then perform amplitude modulation on the phase-modulated signal to generate a corresponding subband noise correction signal C i. The phase modulation of the subband noise signal S i may include inversion of the phase of the subband noise signal S i. Optionally, in some embodiments, the phase displacement (or shift) of the noise 210 may occur during transmission from the location of the subband noise sensor 220 to the location of the output module 170 (e.g., from a location outside the audio broadcasting device to a location of a speaker within the audio broadcasting device). The phase modulation of the subband noise signal S i may further include compensation for the phase displacement of the subband noise signal S i during signal transmission. Alternatively, the sub-band noise reduction module 230-i may first perform amplitude modulation on the sub-band noise signal S i to generate an amplitude-modulated signal, and then perform phase modulation on the amplitude-modulated signal to generate the sub-band noise correction signal C i . Further description of the sub-band noise reduction module 230-i may be found elsewhere in this disclosure. See, for example, Figures 7-9 and their associated descriptions.

[0062] The combining module 240 may be configured to combine the sub-band noise compensation signals to generate a noise compensation signal, as shown in FIG. 2. The combining module 240 may include any component capable of combining multiple signals. For example, the combining module 240 may generate a mixed signal (i.e., a noise compensation signal) according to a signal combining technique, such as a frequency division multiplexing technique. In some alternative embodiments, the combining module 240 may be an independent component or part of a component other than the noise reduction device 200 (e.g., the output module 170). Alternatively, the combining module 240 may be omitted, and the sub-band noise compensation signals may be sent in parallel to the output module 170 for output, as described in connection with FIG. 3.

[0063] The output module 170 may be configured to receive the noise corrected signal from the synthesis module 240. The output of the noise corrected signal by the output module 170 may be performed similarly to the output of the ambient noise corrected signal 130 as described in connection with FIG 1A. For example, the output module 170 may convert the noise corrected signal into an audio signal for output, or process the noise corrected signal and convert the processed noise corrected signal into an audio signal for output.

[0064] In some embodiments, one or more components of the noise reduction system 100A (or the noise reduction system 100B) may be implemented, respectively or together, in one or more components of the noise reduction device 200. For example, the ambient noise reduction device 120 may be implemented by one or more components of the noise reduction device 200. The sub-band noise sensor 220 of the ambient noise reduction device 120 may be spaced a distance greater than a threshold distance from the output module 170 to detect the ambient noise. By way of example only, the sub-band noise sensor 220 may be mounted external to the audio broadcasting device, and the output module 170 may be mounted within the audio broadcasting device. Additionally or alternatively, the residual noise reduction device 150 may be implemented by one or more components of the noise reduction device 200. The sub-band noise sensor 220 of the residual noise reduction device 150 may be mounted near or inside the output module 170 (e.g., located within a threshold distance from the output module 170) to detect the residual noise in the noise reduction. For example, the sub-band noise sensor 220 and the output module 170 may both be implemented inside an audio broadcasting device in close proximity to each other.

[0065] FIG. 3 is a schematic diagram illustrating an exemplary noise reduction device 300 according to some embodiments of the present disclosure. The noise reduction device 300 may be similar to the noise reduction device 200, except for certain components or features. As shown in FIG. 3, the output module 170 may include multiple output units 170-1, 170-2, ..., and 170-m. The subband noise correction signals generated by the subband noise reduction module 230 may be sent to the output unit 170 in parallel without being combined. Each of the output units may be configured to receive one of the subband noise correction signals and output the received subband noise correction signal. In some embodiments, similar to the noise reduction device 200, the noise reduction device 300 may be used to implement one or more components of the noise reduction system 100A (or the noise reduction system 100B), such as the ambient noise reduction device 120 and / or the residual noise reduction device 150.

[0066] It should be noted that the above description of the noise reduction device 200, 300 is illustrative and is not intended to limit the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the noise reduction device 200 and / or the noise reduction device 300 may include one or more additional components. Additionally or alternatively, one or more components of the noise reduction device 200 and / or the noise reduction device 300 described above, such as the synthesis module 240, may be omitted. As another example, two or more components of the noise reduction device 200 and / or the noise reduction system 300 may be integrated into a single component. By way of example only, the synthesis module 240 and / or the output module 170 of the noise reduction device 200 may be integrated into the sub-band noise reduction module 230 of the noise reduction device 200.

[0067] 4 is a schematic diagram illustrating an example sub-band noise sensor 220A according to some embodiments of the present disclosure. The sub-band noise sensor 220A may be an example embodiment of the sub-band noise sensor 220 as described in connection with FIG. 2. As shown in FIG. 4, the sub-band noise sensor 220A may include an acoustoelectric transducer 410 and a band splitting module 420 coupled to the acoustoelectric transducer 410.

[0068] The acoustoelectric transducer 410 may be configured to detect the noise 210 and convert the noise 210 into an electrical signal. The frequency band of the electrical signal may be the same (or substantially the same) as the frequency band of the noise 210. The acoustoelectric transducer 410 may include a microphone, a hydrophone, an acousto-optical modulator (AOM), or any other device capable of converting an audio signal into an electrical signal, or any combination thereof.

[0069] The band splitting module 420 may be configured to split the electrical signal into a plurality of sub-band noise signals (e.g., sub-band noise signals S1-Sm). In some embodiments, the band splitting module 420 may include a plurality of band-pass filters. Each of the band-pass filters may have a unique frequency response and be configured to generate one of the sub-band noise signals by processing the electrical signal. The frequency response of a band-pass filter may refer to a quantitative measure of the output spectrum of the band-pass filter (i.e., the corresponding sub-band noise signal) in response to an input (i.e., the electrical signal). For example, the frequency response of a band-pass filter may include a center frequency, a frequency bandwidth, a cut-off frequency, etc., or any combination thereof.

[0070] In some embodiments, the combination of frequency bands of the sub-band noise signals can cover the frequency band of the noise 210. The frequency bandwidths of different sub-band noise signals can be the same or different from each other. Additionally or alternatively, overlap between the frequency bands of a pair of adjacent sub-band noise signals in the frequency domain can be avoided. To this end, in some embodiments, the frequency responses of two band-pass filters generating a pair of adjacent sub-band noise signals can intersect at a certain frequency point that meets a certain condition.

[0071] For illustrative purposes, FIG. 5A shows an example frequency response 510 of a first bandpass filter and an example frequency response 520 of a second bandpass filter according to some embodiments of the present disclosure. FIG. 5B shows another example frequency response 510 of a first bandpass filter and a second bandpass filter 530 according to some embodiments of the present disclosure. The first bandpass filter may be configured to process the electrical signal generated by the acoustoelectric transducer 410 to generate a first sub-band noise signal of the sub-band noise signal. The second bandpass filter may be configured to process the electrical signal generated by the acoustoelectric transducer 410 to generate a second sub-band noise signal of the sub-band noise signal. The second sub-band noise signal may be adjacent to the first sub-band noise signal of the sub-band noise signals in the frequency domain.

[0072] In some embodiments, the frequency responses of the first and second bandpass filters may have the same frequency bandwidth. For example, as shown in FIG. 5A, the frequency response 510 of the first bandpass filter has a lower half-power point f1, an upper half-power point f2, and a center frequency f3. As used herein, the half-power point of a particular frequency response may refer to a frequency point having a particular attenuation of a level of power (e.g., -3 dB). The frequency bandwidth of the frequency response 510 may be equal to the difference between f2 and f1. The frequency response 520 of the second bandpass filter has a lower half-power point f2, an upper half-power point f4, and a center frequency f5. The frequency bandwidth of the frequency response 520 may be equal to the difference between f4 and f2. The frequency bandwidths of the first and second bandpass filters may be equal to each other.

[0073] Alternatively, the frequency responses of the first and second bandpass filters may have different frequency bandwidths. For example, as shown in FIG. 5B, the frequency response 530 of the second bandpass filter has a lower half-power point f2, an upper half-power point f7 (greater than f4), and a center frequency f6. The frequency bandwidth of the frequency response 530 of the second bandpass filter may be equal to the difference between f7 and f2, which may be greater than the frequency bandwidth of the frequency response 510 of the first bandpass filter. In this way, fewer bandpass filters may be required in the band splitting module 420 to generate multiple sub-band noise signals to cover the frequency bands of the noise 210.

[0074] In some embodiments, the frequency responses of the first bandpass filter and the second bandpass filter may intersect at a particular frequency point. In some embodiments, the particular frequency point at which the frequency responses of the first and second bandpass filters intersect may be near the half-power point of the frequency response of the first bandpass filter and / or the half-power point of the frequency response of the second bandpass filter. Taking FIG. 5A as an example, the frequency response 510 and the frequency response 520 intersect at the upper half-power point f2 of the frequency response 510, which is also the lower half-power point of the frequency response 520. As used herein, a frequency point may be considered to be near the half-power point if the power level difference between the frequency point and the half-power point is equal to or less than a threshold value (e.g., 2 dB). In such a case, there may be less loss or repetition of energy in the frequency responses of the first and second bandpass filters, which may result in a suitable overlap range between the frequency responses of the first and second bandpass filters. In some embodiments, the overlap range may be considered relatively small if the frequency responses intersect at frequency points with power levels greater than -5 dB and / or less than -1 dB. In some embodiments, the center frequency and / or bandwidth of the frequency responses of the first and second bandpass filters may be adjusted to obtain a narrower or more appropriate overlap range between the frequency responses of the first and second bandpass filters to avoid overlap between the frequency bands of the first and second sub-band noise signals. In some embodiments, the frequency response of the band splitting module 420 may have a variation in power level within ±1 dB.

[0075] It should be noted that the examples shown in Figures 5A and 5B are intended to be illustrative and do not limit the scope of the present disclosure. A person skilled in the art can make multiple variations and modifications under the teachings of the present disclosure. However, these variations and modifications do not depart from the scope of the present disclosure. For example, one or more parameters (e.g., frequency bandwidth, upper half-power point, lower half-power point, and / or center frequency) of the frequency response of the first bandpass filter and / or the second bandpass filter may be variable.

[0076] In some embodiments, the bandpass filters of the band splitting module 420 may include Butterworth filters, Chebyshev filters, Cauer filters, etc., or any combination thereof. The steepness of the edges of the frequency response of the bandpass filters may be associated with the type and / or order of the bandpass filters. For example, the steepness of the edges of a Butterworth filter with a certain order may be greater than the steepness of the edges of a Chebyshev filter with the same order. The steepness of the edges of a Chebyshev filter with a certain order may be greater than the steepness of a Cauer filter with the same order. For a certain bandpass filter with a certain center frequency, the steepness of the edges of the frequency response of the bandpass filter may increase with the order of the bandpass filter. In some embodiments, the type of bandpass filter of the band splitting module 420 may be selected according to the frequency band of the noise 210 to be reduced. For example, a bandpass filter having a high order (e.g., an order greater than the order of the threshold) and a narrow bandwidth (e.g., a frequency bandwidth smaller than a second threshold bandwidth) can be utilized to suppress narrow bandwidth noise (e.g., a frequency bandwidth smaller than a first threshold bandwidth), such as narrow bandwidth low frequency noise or high frequency noise. The first and second threshold bandwidths may be the same or different from each other.

[0077] In some embodiments, the bandpass filters of the band splitting module 420 may be finite impulse response filters whose impulse response is of finite duration, or infinite impulse response filters, which are linearly dependent on a finite number of input samples and a finite number of previous filter outputs.

[0078] In some embodiments, the sub-band noise signals generated by the band splitting module 420 may be output in parallel (e.g., via multiple electrical cables) for further processing. For example, each bandpass filter of the band splitting module 420 may be electrically connected to a sub-band noise reduction module (e.g., the sub-band noise reduction module 230), and the sub-band noise signals generated by the bandpass filters may be sent to the connected sub-band noise reduction module to generate corresponding sub-band noise compensation signals. Alternatively, the sub-band noise signals may be processed to generate single-channel signals, for example, using frequency division multiplexing techniques, and output for further processing. In some embodiments, multiple sub-band noise reduction modules may be integrated into the band splitting module 420. The integrated band splitting module may generate sub-band noise signals and further generate multiple sub-band noise compensation signals for reducing the sub-band noise signals. Further description regarding the integrated band splitting module may be found elsewhere in this disclosure. See, for example, FIG. 10 and its related description.

[0079] It should be noted that the above description of the sub-band noise sensor 220A is illustrative and is not intended to limit the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the sub-band noise sensor 220A can include one or more additional components. Additionally or alternatively, one or more components of the sub-band noise sensor 220A described above may be omitted. As another example, two or more components of the sub-band noise sensor 220A may be integrated into a single component.

[0080] 6 is a schematic diagram illustrating an example sub-band noise sensor 220B according to some embodiments of the present disclosure. The sub-band noise sensor 220B may be an example embodiment of the sub-band noise sensor 220 as described in connection with FIG. The sub-band noise sensor 220B may be configured to detect the noise 210 and generate a plurality of sub-band noise signals (e.g., sub-band noise signals S1-Sm) in response to the detected noise 210.

[0081] As shown in FIG. 6, sub-band noise sensor 220B may include a plurality of acoustoelectric transducers 610 (e.g., acoustoelectric transducers 610-1 to 610-m) and a plurality of sampling modules 620 (e.g., sampling modules 620-1 to 620-m). Each of acoustoelectric transducers 610 may have a unique frequency response and may be configured to generate a sub-band noise electrical signal by processing noise 210. The sub-band noise electrical signal generated by acoustoelectric transducer 610 may be an analog signal. Each of sampling modules 620 may be configured to receive one of the sub-band noise electrical signals and sample the received sub-band electrical signal to generate one of the sub-band noise signals (i.e., a digital signal).

[0082] In some embodiments, the count (or number) of acoustoelectric transducers 610 and the count (or number) of sampling modules 620 may both be equal to the count (or number) of sub-band noise signals (i.e., m). The value of m may be related to the frequency band of noise 210 and the frequency band of the generated sub-band noise signals. For example, a certain number of acoustoelectric transducers 610 may not be utilized such that a combination of the frequency bands of the sub-band noise signals can cover the frequency band of noise 210. Additionally or alternatively, overlap between the frequency bands of a pair of adjacent ones of the sub-band noise signals may be avoided.

[0083] In some embodiments, the acoustoelectric transducer 610 may include an acoustic channel component and a sensorineural component. The acoustic channel component may form a path through which the audio signal (e.g., the noise 210) is transmitted to the sensorineural component. For example, the acoustic channel component may include one or more chamber structures, one or more pipe structures, etc., or a combination thereof. The sensorineural component may convert the audio signal transmitted from the acoustic channel component (e.g., the original noise 210 or the processed noise after passing through the acoustic channel component) into an electrical signal. For example, the sensorineural component 420 may include a diaphragm, a plate, a cantilever, etc. Taking the figure as an example, the diaphragm may be used to convert the change in sound pressure caused by the audio signal on the diaphragm surface into a mechanical vibration of the diaphragm. The sensorineural component may be made of one or more materials, including, for example, plastic, metal, piezoelectric material, etc., or any composite material.

[0084] In some embodiments, the frequency response of the acoustoelectric transducer 610 may be associated with the acoustic structure of the acoustic channel components of the acoustoelectric transducer 610. For example, the acoustic channel components of the acoustoelectric transducer 610-i may have a particular acoustic structure that can process the noise 210 before it reaches the sensorineural components of the acoustoelectric transducer 610-i. In some embodiments, the acoustic structure of the acoustic channel components may have a particular acoustic impedance such that the acoustic channel components may act as filters that filter the noise 210 to generate sub-band noise. The sensorineural components of the acoustoelectric transducer 610-i may then convert the sub-band noise into a sub-band noise electrical signal Ei.

[0085] In some embodiments, the acoustic impedance of the acoustic structure may be set according to the frequency band of the noise 210. In some embodiments, the acoustic structure mainly including the chamber structure may function as a high-pass filter, while the acoustic structure mainly including the pipe structure may function as a low-pass filter. By way of example only, the acoustic channel component may have a chamber-pipe structure. The chamber-pipe structure may be a combination of an acoustic capacitance and an acoustic mass in series, and an inductor-capacitor (LC) resonant circuit may be formed. When an acoustic resistive material is used in the chamber-pipe structure, a resistor-inductor-capacitor (RLC) series loop may be formed, and the acoustic impedance of the RLC series loop may be determined according to the following equation (1):

number

[0086] The chamber-pipe structure can function as a bandpass filter (denoted as F1). The bandwidth of the bandpass filter F1 is given by the acoustic resistance R a The center frequency ω0 of the bandpass filter F1 may be adjusted by adjusting the acoustic mass M a and / or acoustic capacitance C a For example, the center frequency ω0 of the bandpass filter F1 can be calculated according to the following equation (2).

number

[0087] In some embodiments, the frequency response of the acoustoelectric transducer 610 may be related to the physical properties (e.g., material, structure) of the sensory component of the acoustoelectric transducer 610. A sensory component having certain physical properties may be sensitive to a certain frequency band of the noise 210. For example, mechanical vibration of one or more elements in the sensory component may result in a change in the electrical parameter of the sensory component. The sensory component may be sensitive to a certain frequency band of the audio signal. The frequency band of the audio signal may cause a corresponding change in the electrical parameter of the sensory component. In other words, the diagram may function as a filter that processes a sub-band of the audio signal. In some embodiments, the noise 210 may be transmitted to the sensory component through the acoustic channel component without being filtered (or substantially unfiltered) by the acoustic channel component. The physical properties of the sensory component may be adjusted so that the sensory component can function as a filter that filters the noise 210 and converts the filtered noise into a sub-band noise electrical signal.

[0088] By way of example only, the sensory component may include a diaphragm that may function as a bandpass filter (denoted as F2). The center frequency ω′0 of the bandpass filter F2 may be determined according to the following equation (3):

number

[0089] As described above, the acoustic channel components or sensorineural components of acoustoelectric transducer 610 may function as filters. The frequency response of acoustoelectric transducer 610 may be determined by the parameters of the acoustic channel components (e.g., R a , M a , and / or C. a ) or parameters of the sensorineural components (e.g., K m and / or R m ) can be adjusted. In some alternative embodiments, the combination of the acoustic channel components and the sensorineural components may act as a filter. By changing the parameters of the acoustic channel components and the sensorineural components, the frequency response of the combination of the acoustic channel components and the sensorineural components can be adjusted accordingly. Further description regarding acoustic channel components and / or sensorineural components acting as bandpass filters can be found, for example, in PCT Application No. PCT / CN2018 / 105161, filed September 12, 2018, entitled "SIGNAL PROCESSING DEVICE HAVING MULTIPLE ACOUSTIC-ELECTRIC TRANSDUCERS," the contents of which are incorporated herein by reference.

[0090] In some embodiments, the acoustoelectric transducer 610 may have a particular frequency response such that the frequency band of the subband noise signal generated by the subband noise sensor 220B can cover the frequency band of the noise 210 and / or avoid overlap between the frequency bands of a pair of adjacent subband noise signals. To this end, in some embodiments, the frequency response of the acoustoelectric transducer 610 corresponding to a pair of adjacent subband noise signals may have characteristics that are the same as or similar to the characteristics of the bandpass filter that generates the pair of adjacent subband noise signals, as described in connection with FIG.

[0091] For example, a first acoustoelectric transducer 610 having a first frequency response may generate a subband noise electrical signal corresponding to a first subband noise signal of the subband noise signals. A second acoustoelectric transducer 610 having a second frequency response may generate a subband noise electrical signal corresponding to a second subband noise signal adjacent to the first subband noise signal in the frequency domain. The first and second frequency responses may intersect at a frequency point near a half-power point of the first frequency response and / or a half-power point of the second frequency response. By way of example only, the first frequency response of the first acoustoelectric transducer may be similar to a frequency response 510 of a first bandpass filter as shown in FIG. 5A and FIG. 5B. The second frequency response of the second acoustoelectric transducer may be similar to a frequency response 520 of a second bandpass filter as shown in FIG. 5A or a frequency response 530 of a second bandpass filter as shown in FIG. 5B.

[0092] In some embodiments, the acoustoelectric transducer 610 can transmit the generated sub-band noise electrical signal to the sampling module 620 via one or more transmitters. Exemplary transmitters may be a coaxial cable, a communication cable (e.g., a telecommunications cable), a flexible cable, a helical cable, a non-metallic sheathed cable, a metallic sheathed cable, a multi-core cable, a twisted pair cable, a ribbon cable, a shielded cable, a double-stranded cable, an optical fiber, or the like, or a combination thereof. In some embodiments, the sub-band noise electrical signal may be transmitted to the sampling module 620 via multiple sub-band transmitters connected in parallel. Each of the multiple sub-band transmitters may connect to the acoustoelectric transducer 610 and transmit the sub-band noise electrical signal generated by the acoustoelectric transducer 610 to the corresponding sampling module 620. Alternatively, the sub-band noise electrical signal may be processed into a single channel signal, for example, using a frequency division multiplexing technique, and transmitted to the sampling module 620 via a single transmitter.

[0093] In some embodiments, the sampling module 620 may sample the sub-band noise electrical signals using a specific sampling frequency. In some embodiments, the sampling frequencies of the different sampling modules 620 may be the same. For example, the specific sub-band noise electrical signal may have the largest center frequency among all the sub-band noise electrical signals, and the sampling frequency of each sampling module 620 may be greater than twice the highest frequency in the frequency band of the specific sub-band noise electrical signal. This can avoid signal distortion and frequency aliasing between the sub-band noise signals generated by the sampling module 620. However, using a high sampling frequency (e.g., a sampling frequency higher than the threshold frequency) may require more processing load and / or time.

[0094] Alternatively, the sampling frequencies of the different sampling modules 620 may differ according to the frequency band of the sub-band noise electrical signal to be sampled. For example, the sampling frequency of the sampling module 620-i may be greater than twice the highest frequency in the frequency band of the sub-band noise electrical signal Ei. In some embodiments, the sampling module 620-i may sample the sub-band noise electrical signal Ei according to a band-pass sampling technique. For example, the sampling frequency of the sampling module 620-i may be greater than twice the frequency bandwidth of the sub-band noise electrical signal Ei and / or less than four times the frequency bandwidth of the sub-band noise electrical signal Ei. As another example, the frequency band of the sub-band noise electrical signal Ei may be (f L , f H ), the sampling frequency f of the subband noise electrical signal Ei is S can be calculated according to the following formula (4).

number

[0095] In some embodiments, the subband noise signals generated by the sampling modules 620 having different sampling frequencies may have different sampling periods. Multiple subband noise reduction modules (e.g., subband noise reduction modules 230) can receive subband noise signals from the subband noise sensor 220B and generate multiple subband noise correction signals. The subband noise correction signals may have different sampling periods. The subband noise correction signals may need to be combined to generate a noise correction signal according to some embodiments of the present disclosure, as described elsewhere in this disclosure (e.g., FIG. 2 and related descriptions). Before being combined, the subband noise correction signals may be subjected to downsampling or upsampling so that the sampling periods of the subband noise correction signals are adjusted to the same value.

[0096] It should be noted that the above description of the sub-band noise sensor 220B is illustrative and is not intended to limit the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, one or more components of the sub-band noise sensor 220B described above may be omitted. In some embodiments, the acoustoelectric transducer 610 may directly generate a sub-band noise signal in the form of a digital signal by processing the noise 210, and the sampling module 620 may be omitted. Additionally or alternatively, the sub-band noise sensor 220B may include one or more additional components.

[0097] 7 is a schematic diagram illustrating an example sub-band noise reduction module 700 according to some embodiments of the present disclosure. The sub-band noise reduction module 700 may be an example embodiment of the sub-band noise reduction module 230-i as described in connection with FIGs. 2 and 3. The sub-band noise reduction module 700 receives one of the sub-band noise signals S from a sub-band noise sensor (e.g., the sub-band noise sensor 220). i (n) and receiving the subband noise signal S i Subband noise correction signal A for reducing (n) t S' i (n). A t may refer to an amplitude attenuation factor for the noise to be reduced (eg, noise 210).

[0098] 7, the sub-band noise reduction module 700 can include a phase modulator 710 and an amplitude modulator 720. The phase modulator 710 converts the sub-band noise signal S i (n) and receiving the subband noise signal S i (n) to obtain a phase-modulated signal S' i For example, as shown in FIG. i (n) is the subband noise signal S i (n). In some embodiments, the phase displacement (or shift) of the noise may be i The phase shift may occur during transmission from the location of the sub-band noise sensor that generates the sub-band noise signal S(n) to the location of the output module (e.g., output module 170) or a portion thereof (e.g., output unit). In some embodiments, the phase shift may be ignored. The phase modulator 710 modulates the sub-band noise signal S i By simply inverting the phase of (n), the phase-modulated signal S' i(n) can be generated. If the frequency of the sound is lower than the cutoff frequency of the ear canal, the sound can be transmitted in the form of a plane wave in the ear canal. For illustrative purposes, the ear canal can be considered as a tubular conduit having a certain radius, and its cutoff frequency can be determined according to the following equation (5).

number

[0099] The amplitude modulator 720 generates a phase modulated signal S' i (n) and receiving the phase modulated signal S' i (n) to obtain the correction signal A t S' i In some embodiments, the amplitude of the noise can be attenuated during transmission from the location of the sub-band noise sensor to the location of the output module (or a portion thereof). To measure the amplitude attenuation of the noise during transmission, an amplitude attenuation coefficient A t can be determined. The amplitude attenuation coefficient A tmay be related to one or more factors including, for example, the material and / or structure of the acoustic channel components along which the noise is transmitted, the position of the sub-band noise sensor relative to the output module (or portion thereof), etc., or any combination thereof. In some embodiments, the amplitude attenuation coefficient A t may be a default setting for the noise reduction system 100A (or 100B) or may be determined prior to actual or simulated experimentation. t may be determined by comparing the amplitude of the audio signal near the sub-band noise sensor (e.g., before it enters the audio broadcasting device) with the amplitude of the audio signal after it has been transmitted to the location of the output module. In some alternative embodiments, e.g., if the attenuation of the amplitude during transmission of the noise is less than a threshold value and / or if the amplitude attenuation coefficient A t is substantially equal to 1, the amplitude attenuation of the noise may be neglected. In such a case, the phase modulated signal S' i (n) is the subband noise signal S i (n) may be specified as the subband noise compensation signal.

[0100] In some embodiments, a noise reduction device (e.g., noise reduction device 200, noise reduction device 300) may include multiple sub-band noise reduction modules 230. Each of the sub-band noise reduction modules 230 may have the same or similar structure as the sub-band noise reduction module 700, as shown in Figure 7, and may be configured to generate a corresponding sub-band noise correction signal. The multiple sub-noise correction signals may be combined into one noise correction signal S(n) according to the following equation (6):

number

[0101] 9 is a schematic diagram illustrating an example sub-band noise reduction module 900 according to some embodiments of the present disclosure. The sub-band noise reduction module 900 may be an example embodiment of the sub-band noise reduction module 230-i described in relation to FIG. 2 and FIG. 3. The sub-band noise reduction module 900 includes a phase modulator 710 for modulating a sub-band noise signal S during signal transmission. i Taking into account the phase shift of (n), the subband noise signal S i 7. The subband noise reduction module 700 may be similar to the subband noise reduction module 700, except that it may be configured to modulate the phase of (n).

[0102] By way of example only, a subband noise signal S i The phase of (n) may have a phase displacement Δφ during transmission from the position of the sub-band noise sensor (e.g., the sub-band noise sensor 220) to the position of the output module (e.g., the output module 170) or a part thereof (e.g., the output unit). The phase displacement Δφ may be determined according to the following equation (7):

number

[0103] To compensate for the phase shift Δφ, the phase modulator 710 performs phase inversion and phase compensation on the subband noise signal S i (n) to generate a phase-modulated signal. In some embodiments, the phase modulator 710 may include an all-pass filter. The filter function of the all-pass filter may be expressed as H(w), where w refers to the angular frequency. In an ideal situation, the magnitude response of the all-pass filter |H(w)| may be equal to 1, and the phase response of the all-pass filter may be equal to the phase displacement Δφ. The all-pass filter may filter the sub-band noise signal S to perform phase compensation. i (n) may be delayed by a time delay ΔT, which may be determined according to equation (8) below:

number

[0104] In such a case, the phase modulator 710 generates the sub-band noise signal S i (n) is subjected to phase inversion and phase compensation to obtain a phase-modulated signal S' i The amplitude modulator 720 may generate an amplitude attenuation coefficient A(n-ΔT) as described in FIG. t Based on the phase modulation signal S' i The amplitude of (n-ΔT) is further modulated to obtain the subband noise signal S i (n) to reduce the subband noise correction signal (i.e., A t S' i (n-ΔT) can be generated.

[0105] In some embodiments, the noise reduction device may include multiple sub-band noise reduction modules 230. Each of the sub-band noise reduction modules 230 may have the same or similar structure as the sub-band noise reduction module 900, as shown in FIG. 9, and may be configured to generate a corresponding sub-band noise correction signal. The multiple sub-noise correction signals are combined into one noise correction signal S according to the following equation (9): i It can be synthesized into (n).

number

[0106] It should be noted that the above description of Figures 7 and 9 is intended to be illustrative and not limiting of the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the sub-band noise reduction module 700 and / or 900 can include one or more additional components. Additionally or alternatively, one or more components of the sub-band noise reduction module 700 and / or 900, such as the amplitude modulator 702 described above, may be omitted.

[0107] In some alternative embodiments, the sub-band noise signal S i (n) may be sent to the amplitude modulator 720 for amplitude modulation and then sent to the phase modulator 710 for phase modulation. For example, the amplitude modulator 720 may be configured to modulate the amplitude attenuation coefficient A t and performing phase modulation (eg, phase inversion and optionally phase compensation) on the amplitude modulated signal to generate a corresponding sub-band noise correction signal.

[0108] 10 is a schematic diagram illustrating an example sub-band noise sensor 220C according to some embodiments of the present disclosure. The sub-band noise sensor 220C may be an example embodiment of the sub-band noise sensor 220A described in relation to FIG. 4. A sub-band noise reduction module (e.g., the sub-band noise reduction module 230) may be integrated into the sub-band noise sensor 220C so that the sub-band noise sensor 220C can implement the functions of both the sub-band noise sensor 220A and the sub-band noise reduction module. In other words, the sub-band noise sensor 220C may be configured to detect the noise 210 and generate a plurality of sub-band noise signals and a plurality of sub-band noise correction signals for correcting the sub-band noise signals.

[0109] As shown in FIG. 10, the sub-band noise sensor 220C may include an acoustoelectric transducer 410 and a band splitting module 1010. Similar to the band splitting module 420 described in relation to FIG. 4, the band splitting module 1010 may include a plurality of bandpass filters, each of which may perform bandpass filtering on the electrical signal generated by the acoustoelectric transducer 410 to generate a plurality of sub-band noise signals. Each bandpass filter may further include a digital signal processor that may implement the functionality of a sub-band noise reduction module (e.g., the sub-band noise reduction module 700 or 900 as described in relation to FIG. 7 and FIG. 9). By way of example only, the digital signal processor may perform phase modulation and / or amplitude modulation on the sub-band noise signals to generate corresponding sub-band noise correction signals. In this manner, the sub-band noise reduction module may be omitted from the noise reduction device, simplifying the structure of the noise reduction device.

[0110] It should be noted that the above description of the sub-band noise sensor 220C is intended to be illustrative and not limiting of the scope of the present disclosure. Many alternatives, modifications, and variations will be apparent to those skilled in the art. The features, structures, methods, and other characteristics of the exemplary embodiments described herein can be combined in various ways to obtain additional and / or alternative exemplary embodiments. For example, the sub-band noise sensor 220C can include one or more additional components. Additionally or alternatively, one or more components of the sub-band noise sensor 220C described above may be omitted. In some embodiments, the band splitting module 1010 can generate the sub-band noise correction signal without performing amplitude modulation.

[0111] 11 is a schematic diagram illustrating an exemplary noise reduction system 1100 according to some embodiments of the present disclosure. The noise reduction system 1100 may be an exemplary embodiment of the noise reduction system 100A described in connection with FIG. 1A. As shown in FIG. 11, the noise reduction system 1100 may include an ambient noise reduction device 120A, a residual noise reduction device 150A, a synthesis module 1120, and an output module 170. The ambient noise reduction device 120A and the residual noise reduction device 150A may be exemplary embodiments of the ambient noise reduction device 120 and the residual noise reduction device 150, respectively.

[0112] The ambient noise reduction device 120A may be configured to reduce the ambient noise 110 using a sub-band noise reduction technique. As shown in FIG. 11, the ambient noise reduction device 120A may have a similar structure to the noise reduction device 200 described in connection with FIG. 2. The ambient noise reduction device 120A may include a sub-band noise sensor 220, a plurality of sub-band noise reduction modules 230, and a synthesis module 240. The sub-band noise sensor 220 may detect the ambient noise 110 and generate a plurality of sub-band ambient noise signals (e.g., sub-band ambient noise signals A1-Am). The sub-band ambient noise signals generated in response to the ambient noise 110 may be similar to the sub-band noise signals generated in response to the noise 210, as described in connection with FIG. 2.

[0113] The subband noise reduction module 230 may generate a plurality of subband ambient noise compensation signals (e.g., subband ambient noise compensation signals A1′-Am′), each of which is used to reduce one of the subband ambient noise signals. The subband ambient noise compensation signals for reducing the subband ambient noise signals may be similar to the subband noise compensation signals for reducing the subband noise signals as described in relation to FIG. 2. The synthesis module 240 may combine the subband ambient noise compensation signals to generate the ambient noise compensation signal 130 and send the ambient noise compensation signal 130 to the synthesis module 1120.

[0114] The residual noise reduction device 150A may be configured to reduce the residual noise 140 using a full-band noise reduction technique. The residual noise reduction device 150A may include a residual noise sensor 1130 and a residual noise reduction module 1110. The residual noise sensor 1130 may be configured to detect the residual noise 140 and generate a residual noise signal in response to the detected residual noise 140. For example, the residual noise sensor 1130 may include a single acoustoelectric transducer that generates a residual noise signal having the same (or substantially the same) frequency band as the residual noise 140. In some embodiments, the residual noise sensor 1130 may be mounted near or within the output module 170. For example, the residual noise sensor 1130 may be mounted within the output module 170 near an acoustic channel in which an audio signal for reducing the ambient noise 110 is generated. The residual noise reduction module 1110 may be configured to receive the residual noise signal from the residual noise sensor 1130 and generate a residual noise correction signal 160 for reducing the residual noise 140. The residual noise compensation signal 160 generated by the residual noise reduction module 1110 may be transmitted to the synthesis module 1120 .

[0115] In some alternative embodiments, the residual noise reduction device 150A may utilize a sub-band noise reduction technique to reduce the residual noise 140. By way of example only, the residual noise reduction device 150A may have a structure similar to the noise reduction device 200 as described in connection with FIG. 2. The residual noise sensor 1130 and the residual noise reduction module 1110 may have functions similar to the sub-band noise sensor 220 and the sub-band noise reduction module 230, respectively. The residual noise signal generated by the residual noise sensor 1130 may include multiple sub-band residual noise signals, each of which may have a narrower frequency band than the residual noise 140. The residual noise correction signal 160 generated by the residual noise reduction module 1110 may include multiple sub-band residual noise correction signals for reducing the sub-band residual noise signal, or may be a composite signal of the sub-band residual noise correction signals.

[0116] The combination module 1120 may be configured to combine the ambient noise compensated signal 130 and the residual noise compensated signal 160 to generate a combined signal, which may be sent to the output module 170 for output. In some embodiments, the combined signal generated by the combination module 1120 may be a digital signal, and the output module 170 may convert the combined signal into an audio signal for output.

[0117] FIG. 12 is a schematic diagram illustrating an exemplary noise reduction system 1200 according to some embodiments of the present disclosure. The noise reduction system 1200 may be an exemplary embodiment of the noise reduction system 100B described in relation to FIG. 1B. The noise reduction system 1200 may be similar to the noise reduction system 1100 described in relation to FIG. 11, except for certain components or features. Compared with the noise reduction system 1100, the noise reduction system 1200 may further include a D / A converter 1210, a D / A converter 1230, and an output module 180. The ambient noise correction signal 130 generated by the ambient noise reduction device 120A and the residual noise correction signal 160 generated by the residual noise reduction device 150A may be processed and output respectively without being combined.

[0118] In some embodiments, the ambient noise compensation signal 130 and the residual noise compensation signal 160 may be digital signals. The D / A converters 1210 and 1230 may be configured to convert the ambient noise compensation signal 130 and the residual noise compensation signal 160 to analog signals 1220 and 1240, respectively. The analog signal 1220 may be further transmitted from the D / A converter 1210 to the output module 170 for output. The analog signal 1240 may be further transmitted from the D / A converter 1230 to the output module 180 for output.

[0119] 13 is a schematic diagram illustrating an exemplary noise reduction system 1300 according to some embodiments of the present disclosure. The noise reduction system 1300 may be similar to the noise reduction system 1100 described in connection with FIG. 11, except for certain components or features. As shown in FIG. 13, the noise reduction system 1300 may include an ambient noise reduction device 120A, a residual noise reduction device 150B, and an output module 170. The ambient noise correction signal 130 generated by the ambient noise reduction device 120A may be output by the output module 170.

[0120] The residual noise reduction device 150B may include a residual noise sensor 1130 and a feedback module 1310. The feedback module 1310 may be configured to adjust the sub-band noise reduction modules 230 according to the residual noise 140 to suppress the residual noise 140. For example, the adjustment unit may send instructions to one or more of the sub-band noise reduction modules 230 to adjust one or more parameters of the sub-band noise reduction modules 230. By way of example only, as described elsewhere in this disclosure (e.g., FIGS. 7-9 and related descriptions), the sub-band noise reduction modules 230 may include a phase modulator (e.g., phase modulator 710) and / or an amplitude modulator (e.g., amplitude modulator 720). The feedback module 1310 may adjust a time delay (e.g., ΔT) of the phase modulator and / or an amplitude decay coefficient (e.g., A) of the amplitude modulator such that the residual noise is absent or substantially absent after the ambient noise 110 is suppressed by the ambient noise compensation signal 130. t ) can be sent to the sub-band noise reduction module 230 to adjust the residual noise 140. In this way, the sub-band noise reduction module 230 can be automatically adjusted according to the residual noise 140, thereby improving the accuracy and stability of the noise reduction system 1300.

[0121] It should be noted that the above description of FIGS. 11-13 is provided for illustrative purposes only and is not intended to limit the scope of the present disclosure. A person skilled in the art can make multiple variations and modifications under the teachings of the present disclosure. However, those variations and modifications do not depart from the scope of the present disclosure. The noise reduction system (e.g., any of the noise reduction systems 1100, 1200, and 1300) may include one or more additional components, and / or one or more components of the noise reduction system may be omitted. By way of example only, the D / A converter 1210 may be omitted from the noise reduction system 1200 or may be integrated into the output module 170. As another example, in the noise reduction system 1200, the synthesis module 240 may be omitted and the sub-band noise ambient correction signals may be sent to multiple output units of the output module 170 for output.

[0122] 14 is a schematic diagram illustrating an example residual noise reduction device 150C according to some embodiments of the present disclosure. The residual noise reduction device 150C may be an example embodiment of the residual noise reduction device 150, which may be used to reduce the residual noise 140 using sub-band noise reduction techniques.

[0123] As shown in FIG. 14, the residual noise reduction device 150C may have a similar structure to the noise reduction device 200 described in relation to FIG. 2. The residual noise reduction device 150C may include a sub-band noise sensor 220, a plurality of sub-band noise reduction modules 230, and a synthesis module 240. The sub-band noise sensor 220 may be mounted near the output module 170 to detect the residual noise 140 and generate a plurality of sub-band residual noise signals (e.g., sub-band residual noise signals R1 to Rk). The sub-band noise reduction module 230 may generate a plurality of sub-band residual noise compensation signals (e.g., sub-band residual noise compensation signals R'1 to R'k), one of which is for reducing one of the sub-band residual noise signals. The synthesis module 240 may synthesize the sub-band residual noise compensation signals to generate the residual noise compensation signal 160. The residual noise compensation signal 160 may be further sent to the output module 170 for output.

[0124] In some embodiments, the subband noise reduction module 230-i may include a phase modulator (e.g., a phase inverter) configured to perform phase inversion on the corresponding subband residual noise signal Ri. Since the subband noise sensor 220 for detecting the residual noise 140 may be mounted near the output module 170, the subband noise reduction module 230-i may generate the corresponding subband residual noise correction signal Ri′ without performing phase compensation and / or amplitude modulation on the subband residual noise signal Ri.

[0125] 15 is a schematic diagram illustrating an exemplary noise reduction system 1500 according to some embodiments of the present disclosure. The noise reduction system 1500 can be similar to the noise reduction system 1100 described in connection with FIG. 11, except that the noise reduction system 1500 can unitize analog signal processing techniques to reduce noise. As shown in FIG. 15, the noise reduction system 1500 may include an ambient noise reduction device 120B, a residual noise reduction device 150D, a synthesis module 1505, and an output module 170.

[0126] The ambient noise reduction device 120B may include a sub-band noise sensor (not shown in FIG. 15), a plurality of analog signal processing components 1501 (e.g., analog signal processing components 1501-1 to 1501-m), and a synthesis module 1504. The sub-band noise sensor of the ambient noise reduction device 120B may detect the ambient noise 110 and generate sub-band ambient noise signals (e.g., sub-band ambient noise signals N1 to Nm). The sub-band ambient noise signals generated by the sub-band noise sensor of the ambient noise reduction device 120B may be analog signals.

[0127] The analog signal processing component 1501 may have a similar function to the subband noise reduction module 230 of the ambient noise reduction device 120A as described in relation to FIG. 11. For example, the analog signal processing component 1501 may receive a subband ambient noise signal and generate a plurality of subband ambient noise compensation signals (e.g., subband ambient noise compensation signals N1' to Nm'). The subband ambient noise compensation signals generated by the analog signal processing component 1501 may be analog signals. The subband ambient noise compensation signals may be synthesized into the ambient noise compensation signal 130', which may be an analog signal for reducing ambient noise by the synthesis module 1504.

[0128] In some embodiments, the analog signal processing component 1501-i may include one or more first analog circuit components for performing phase modulation on the sub-band ambient noise signal Ni. The phase modulation by the first analog circuit components may be performed in a manner similar to that performed by a phase modulator (e.g., phase modulator 710) as described elsewhere in this disclosure (e.g., FIGS. 7-9 and related descriptions). For example, the first analog circuit components may include an amplifier (e.g., an inverting amplifier) ​​used to perform phase inversion on the sub-band ambient noise signal Ni. Additionally or alternatively, the first analog circuit components may include an analog delay line (e.g., an inductor-capacitor (LC) circuit delay line, active analog delay line) used to perform phase displacement compensation on the sub-band ambient noise signal Ni.

[0129] The residual noise reduction device 150D may include a residual noise sensor 1503 and an analog signal processing component 1502. The residual noise sensor 1503 may detect the residual noise 140 and generate a residual noise signal in the form of an analog signal. The analog signal processing component 1502 may be configured to generate a residual noise compensation signal 160', which may be an analog signal for reducing the residual noise 140. The combination module 1505 may be configured to combine the ambient noise compensation signal 130' and the residual noise compensation signal 160' to generate a combined analog signal. The combined analog signal may be output by the output module 170.

[0130] By using analog signal processing components, the noise reduction system 1500 can reduce the ambient noise and residual noise 140 without a sampling module (e.g., sampling module 620), a D / A converter (e.g., D / A converters 1210, 1230), an A / D converter, etc., thereby simplifying the noise reduction system 1500 and improving the operating speed of the noise reduction system 1500.

[0131] Having thus described the basic concepts, it will be rather clear to those skilled in the art after reading this detailed disclosure that the foregoing detailed disclosure is intended to be presented by way of example only, and is not limiting. Although not expressly stated herein, various changes, improvements, and modifications may be made and are contemplated by those skilled in the art. These changes, improvements, and modifications are intended to be suggested by this disclosure and are within the spirit and scope of the exemplary embodiments of the present disclosure.

[0132] Furthermore, certain terms are used to describe the embodiments of the present disclosure. For example, the terms "one embodiment," "embodiment," and / or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present disclosure. Thus, it is emphasized and should be understood that two or more references to "one embodiment" or "an embodiment" or "alternative embodiments" in various parts of this specification do not necessarily all refer to the same embodiment. Furthermore, certain features, structures, or characteristics can be combined as appropriate in one or more embodiments of the present disclosure.

[0133] Moreover, as will be appreciated by those skilled in the art, aspects of the present disclosure may be illustrated and described herein in any of several patentable classes or contexts, including any new and useful process, machine, manufacture, or composition of matter, or any new and useful improvement thereof. Accordingly, aspects of the present disclosure may be implemented entirely in hardware, entirely in software (including firmware, resident software, microcode, etc.), or in a combination of software and hardware implementations, which may all be referred to generally herein as "units," "modules," or "systems." Furthermore, aspects of the present disclosure may take the form of a computer program product embodied in one or more computer readable medium(s) having computer readable program code embodied therein.

[0134] A computer-readable signal medium may include a propagated data signal having computer-readable program code embodied therein, for example in baseband or as part of a carrier wave. Such a propagated signal may take any of a variety of forms, including electromagnetic, optical, etc., or any suitable combination thereof. A computer-readable signal medium may be any computer-readable medium that can communicate, propagate, or transport a program for use by or in connection with an instruction execution system, apparatus, or device, other than a computer-readable storage medium. The program code embodied on the computer-readable signal medium may be transmitted using any suitable medium, including wireless, wired, fiber optic cable, RF, etc., or any suitable combination thereof.

[0135] Computer program code for performing operations for aspects of the present disclosure can be written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Java, Scala, Smalltalk, Eiffel, JADE, Emerald, C++, C#, VB.NET, Python, the "C" programming language, traditional procedural programming languages ​​such as Visual Basic, Fortran 2003, Perl, COBOL 2002, PHP, ABAP, dynamic programming languages ​​such as Python, Ruby, and Groovy, or other programming languages. The program code can run entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer, partially on a remote computer, or entirely on a remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer via any type of network, including a local area network (LAN) or wide area network (WAN), or the connection may be to an external computer (e.g., via the Internet using an Internet Service Provider) or in a cloud computing environment, or may be provided as a service, such as Software as a Service (SaaS).

[0136] Furthermore, the recited order of processing elements or sequences, or the use of numbers, letters, or other designations, are therefore not intended to limit the claimed processes and methods to any order, unless otherwise stated in the claims. While the above disclosure describes by various examples what are presently believed to be various useful embodiments of the present disclosure, it is to be understood that such details are for the purpose only, and that the appended claims are not limited to the disclosed embodiments, but on the contrary, are intended to cover modifications and configurations that are within the spirit and scope of the disclosed embodiments. For example, implementations of the various components described above may be implemented in hardware devices, but may also be implemented as software-only solutions, such as installation on existing servers or mobile devices.

[0137] Similarly, in the foregoing description of embodiments of the present disclosure, it should be understood that various features may be grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure to aid in understanding one or more of the various embodiments. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed subject matter requires more features than are expressly recited in each claim. Rather, the claimed subject matter may be less than all features of a single foregoing disclosed embodiment. [Explanation of symbols]

[0138] 100A Noise Reduction System 100B Noise Reduction System 110 Ambient Noise 120 Ambient Noise Reduction Device 120A Ambient Noise Reduction Device 120B Ambient Noise Reduction Device 130 Ambient noise compensation signal 130' Ambient noise compensation signal 140 Residual Noise 150 Residual Noise Reduction Device 150A Residual Noise Reduction Device 150B Residual Noise Reduction Device 150C Residual Noise Reduction Device 150D Residual noise reduction device 160 Residual noise correction signal 160' Residual noise correction signal 170 Output module, output unit 180 Additional Output Module 200 Noise Reduction Device 210 Noise 220 Sub-band noise sensor 220A Sub-band Noise Sensor 220B Sub-band Noise Sensor 220C Sub-band Noise Sensor 230 Sub-band Noise Reduction Module 240 Synthesis Module 300 Noise reduction device, noise reduction system 410 Acoustoelectric Transducer 420 Band division module, sensorineural components 510 Frequency response of the first bandpass filter 520 Frequency response of the second bandpass filter 530 Frequency response of the second bandpass filter 610 Acoustoelectric Transducer 620 Sampling Module 700 Sub-band Noise Reduction Module 702 Amplitude Modulator 710 Phase Modulator 720 Amplitude Modulator 900 Sub-band Noise Reduction Module 1010 Band Splitting Module 1100 Noise Reduction System 1110 Residual Noise Reduction Module 1120 Synthesis Module 1130 Residual Noise Sensor 1200 Noise Reduction System 1210 D / A Converter 1220 Analog Signal 1230 D / A Converter 1240 Analog Signal 1300 Noise Reduction System 1310 Feedback Module 1500 Noise Reduction System 1501 Analog Signal Processing Components 1502 Analog Signal Processing Components 1503 Residual Noise Sensor 1504 Synthesis Module 1505 Synthesis Module

Claims

1. 1. A system for noise reduction, comprising: a subband noise sensor configured to detect noise and generate a plurality of subband noise signals in response to the detected noise, each of the subband noise signals having a characteristic subband of a frequency band of the noise; a plurality of subband noise reduction modules, each of the subband noise reduction modules configured to receive one of the subband noise signals from the subband noise sensor and generate a subband noise correction signal to reduce the received subband noise signal; an output module configured to receive the sub-band noise compensation signal and output a noise compensation signal for reducing the noise based on the sub-band noise compensation signal; The sub-band noise sensor includes: a plurality of acoustoelectric transducers, each of the plurality of acoustoelectric transducers having a unique frequency response, the plurality of acoustoelectric transducers being configured to process the noise to generate a sub-band noise electrical signal; a plurality of sampling modules, each of the sampling modules configured to receive one of the sub-band noise electrical signals and sample the received sub-band noise electrical signal to generate one of the sub-band noise signals; Including, the plurality of acoustoelectric transducers have a particular frequency response such that a combination of frequency bands of the subband noise signals covers the frequency band of the noise, and between the plurality of acoustoelectric transducers: a first one of the acoustoelectric transducers configured to generate a sub-band noise electrical signal having a first frequency response and corresponding to a first one of the sub-band noise signals; a second one of the acoustoelectric transducers configured to generate a sub-band noise electrical signal having a second frequency response and corresponding to a second one of the sub-band noise signals, the second sub-band noise signal being adjacent in the frequency domain to the first one of the sub-band noise signals; the first frequency response and the second frequency response intersect at a frequency point near at least one of a half-power point of the first frequency response or a half-power point of the second frequency response. system.

2. The sampling frequencies of the plurality of sampling modules are different according to the frequency bands of the sub-band noise signals to be sampled, the sampling frequency of each of the plurality of sampling modules is equal to or greater than twice the frequency bandwidth of the corresponding sub-band noise signal; The system of claim 1 .

3. Each of the subband noise reduction modules: a phase modulator configured to receive a corresponding sub-band noise signal of the sub-band noise reduction module and generate a phase modulated signal by modulating a phase of the corresponding sub-band noise signal; an amplitude modulator configured to receive the phase modulated signal from the phase modulator and generate the sub-band noise correction signal for reducing the corresponding sub-band noise signal by modulating the amplitude of the phase modulated signal; The system according to claim 1 or 2, comprising:

4. modulating the phase of the corresponding sub-band noise signal inverting the phase of the corresponding subband noise signal; compensation for phase shifts of the corresponding sub-band noise signals in their transmission from the sub-band noise sensors to the phase modulators; The system of claim 3 , comprising:

5. the noise correction signal comprises the sub-band noise correction signal; the output module includes a plurality of output units; each of the output units is configured to receive one of the subband noise-compensated signals generated by the subband noise reduction modules and to output the received subband noise-compensated signal; A system according to any one of claims 1 to 4.

6. The output module includes: receiving the subband noise-compensated signal from the subband noise reduction module; combining the sub-band noise compensation signals to generate the noise compensation signal; outputting the noise correction signal The system according to claim 1 , configured to:

7. the noise comprises ambient noise, and the system comprises: a residual noise sensor configured to detect residual noise and generate a residual noise signal in response to the detected residual noise, wherein a distance between the residual noise sensor and the output module is less than a distance between the sub-band noise sensor and the output module; a residual noise reduction module configured to receive the residual noise signal and generate a residual noise correction signal to reduce the residual noise; The system of claim 1 , further comprising:

8. the residual noise signal generated by the residual noise sensor comprises a plurality of sub-band residual noise signals; the residual noise correction signal comprises a plurality of sub-band residual noise correction signals, each of the sub-band residual noise correction signals configured to reduce one of the sub-band residual noise signals. The system of claim 7.

9. the noise comprises ambient noise, and the system comprises: a residual noise sensor configured to detect residual noise and generate a residual noise signal in response to the detected residual noise, wherein a distance between the residual noise sensor and the output module is less than a distance between the sub-band noise sensor and the output module; a feedback module configured to adjust the subband noise reduction module in response to the residual noise; The system of claim 1 , further comprising:

10. the sub-band noise sensor is mounted adjacent to or within the output module; The noise includes residual noise. A system according to any one of claims 1 to 6.

11. One of the acoustoelectric transducers comprises: an audio channel component configured to filter the noise to generate sub-band noise; a sensorineural component configured to convert the sub-band noise into a sub-band noise electrical signal; The system of claim 1 , comprising:

12. One of the acoustoelectric transducers comprises: a sensorineural component configured to convert the noise into a sub-band noise electrical signal; The system of claim 1 , comprising:

13. The system of claim 1 , wherein the first frequency response of the first acoustoelectric transducer and the second frequency response of the second acoustoelectric transducer have different frequency bandwidths.

14. Each of the subband noise reduction modules comprises: an amplitude modulator configured to receive the corresponding sub-band noise signal and generate an amplitude modulated signal by modulating an amplitude of the corresponding sub-band noise signal; a phase modulator configured to receive the amplitude modulated signal from the amplitude modulator and generate the sub-band noise correction signal for reducing the corresponding sub-band noise signal by modulating a phase of the amplitude modulated signal; The system according to claim 1 or 2, comprising:

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