Apparatus, system, and method for acoustic feedback (AFB) mitigation

Abstract

For example, an acoustic feedback (AFB) mitigator may mitigate AFB between at least one acoustic transducer and at least one acoustic sensor. For example, the AFB mitigator may include a first filter for generating a first filtered signal by filtering a first input signal, where the first input signal may be based on a transducer acoustic pattern output by the acoustic transducer, and a second filter for generating a second filtered signal by filtering the first input signal, where the second filter may include an adaptive filter that may be adapted based on a difference between the AFB mitigated signal and the second filtered signal. For example, the AFB mitigated signal may be based on a difference between the second input signal and the first filtered signal, where the second input signal is based on a sensor acoustic pattern sensed by the acoustic sensor.

Description

[Technical field]

[0001] cross reference This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 308,708, entitled “APPARATUS, SYSTEM, AND METHOD OF ACOUSTIC FEEDBACK (AFB) MITIGATION,” filed February 10, 2022, the entire disclosure of which is incorporated herein by reference.

[0002] Technical Field Aspects described herein generally relate to acoustic feedback (AFB) mitigation. [Background technology]

[0003] In some devices and / or systems, there may be a need for a technical solution to address one or more technical issues of acoustic feedback (AFB) between an acoustic transducer, e.g., a speaker, and an acoustic sensor, e.g., a microphone.

[0004] For simplicity and clarity of illustration, elements shown in the figures have not necessarily been drawn to scale. For example, dimensions of some elements may be exaggerated relative to other elements for clarity of presentation. Furthermore, reference numerals may be repeated among the figures to indicate corresponding or similar elements. The figures are listed below. [Brief description of the drawings]

[0005] [Figure 1] FIG. 1 is a schematic block diagram of an active acoustic control (AAC) system, in accordance with some demonstrative aspects. [Diagram 2] 2 is a schematic diagram of a deployment of components of the AAC system of FIG. 1 in accordance with some demonstrative aspects. [Diagram 3] 1 is a schematic block diagram of an adaptive acoustic feedback (AFB) mitigator implemented within an AAC system in accordance with some demonstrative aspects. [Figure 4] 1 is a schematic block diagram of an adaptive AFB mitigator implemented within an AAC system in accordance with some demonstrative aspects. [Diagram 5] 1 is a schematic block diagram of an adaptive AFB mitigator implemented within an AAC system in accordance with some demonstrative aspects. [Figure 6] 1 is a schematic block diagram of a controller implementing AFB mitigation in accordance with some demonstrative aspects. [Figure 7] 1 is a schematic block diagram of a multiple-input multiple-output (MIMO) prediction unit in accordance with some demonstrative aspects. [Figure 8] 1 is a schematic block diagram of a controller implementing AFB mitigation in accordance with some demonstrative aspects. [Figure 9] FIG. 1 is a schematic diagram of a vehicle including an AAC system, according to some demonstrative embodiments. [Figure 10] 1 is a schematic block diagram of an AFB mitigator, in accordance with some demonstrative aspects. [Figure 11] 1 is a schematic block diagram of a computing device including an AFB mitigator, in accordance with some demonstrative aspects. [Figure 12] 1 is a schematic flow diagram of a method for adaptive AFB mitigation, in accordance with some demonstrative aspects. [Figure 13] FIG. 1 is a schematic block diagram of a product in accordance with some demonstrative aspects. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of some aspects. However, it will be understood by those skilled in the art that some aspects may be practiced without these specific details. In other instances, well-known methods, procedures, components, units and / or circuits have not been described in detail so as not to obscure the description.

[0007] For example, descriptions herein utilizing terms such as "processing," "computing," "calculating," "determining," "establishing," "analyzing," "checking," or the like, may refer to operation(s) and / or process(es) of a computer, computing platform, computing system, or other electronic computing device that manipulates and / or transforms data represented as physical (e.g., electronic) quantities in the computer's registers and / or memory into other data similarly represented as physical quantities in the computer's registers and / or memory or other information storage medium that may store instructions for performing the operations and / or processes.

[0008] The terms "plurality" and "a plurality" as used herein include, for example, "multiple" or "two or more." For example, "a plurality of items" includes two or more items.

[0009] Some portions of the detailed descriptions which follow are presented in terms of algorithms and symbolic representations of operations on data bits or binary digital signals within a computer memory. These algorithmic descriptions and representations may be techniques used by those skilled in the data processing arts to convey the substance of their work to others skilled in the art.

[0010] An algorithm is here, and generally, conceived to be a self-consistent sequence of acts or operations leading to a desired result. These involve physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated. It has proven convenient at times, primarily for reasons of common usage, to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, or the like. However, it should be understood that all of these and similar terms are associated with the appropriate physical quantities and are merely convenient labels applied to these quantities.

[0011] As used herein, the term "circuitry" may refer to, be a part of, or include an application specific integrated circuit (ASIC), an integrated circuit, an electronic circuit, a processor (shared, dedicated, or group), and / or memory (shared, dedicated, or group), combinatorial logic circuitry, and / or other suitable hardware components that execute one or more software or firmware programs, combinatorial logic circuitry, and / or other suitable hardware components that provide the described functionality. In some aspects, some functions associated with a circuit may be implemented in one or more software or firmware modules. In some aspects, a circuit may include logic that is at least partially operable in hardware.

[0012] The term "logic" may refer to, for example, computing logic embedded within a circuit of a computing device and / or computing logic stored within a memory of a computing device. For example, the logic may be accessible by a processor of a computing device to execute the computing logic to perform an operational function and / or operation. In one example, the logic may be embedded within various types of memory and / or firmware, for example, various chips and / or silicon blocks of a processor. The logic may be included within and / or implemented as part of various circuits, for example, radio circuits, receiver circuits, control circuits, transmitter circuits, transceiver circuits, processor circuits, and / or the like. In one example, the logic may be embedded within volatile and / or non-volatile memory, including random access memory, read-only memory, programmable memory, magnetic memory, flash memory, persistent memory, and / or the like. The logic may be executed by one or more processors, for example, using memory, for example, registers, buffers, stacks, and the like, coupled to the one or more processors as necessary to execute the logic.

[0013] Some illustrative aspects include systems and methods that can be implemented to control noise, e.g., to reduce or eliminate undesirable noise, e.g., noise within one or more frequency ranges, e.g., generally low, medium and / or high frequencies, as described below.

[0014] Some demonstrative embodiments may include, for example, active acoustic control (AAC) methods and / or systems configured to control acoustic energy and / or wave amplitude of one or more acoustic patterns generated by one or more acoustic sources, which may include known and / or unknown acoustic sources, as described below.

[0015] In some demonstrative aspects, the AAC system may be configured as and / or perform one or more functions of an active noise control (ANC) system and / or active sound field control (ASC), which may be configured to control, reduce and / or eliminate noise energy and / or wave amplitude of one or more acoustic patterns ("primary patterns") generated by one or more noise sources, which may include known and / or unknown noise sources, e.g., as described below.

[0016] In some demonstrative aspects, the AAC system may be configured to generate sound control patterns (also referred to as "sound control patterns" or "secondary patterns") including, for example, disruptive noise patterns and / or any other sound control patterns, e.g., as described below.

[0017] In some demonstrative aspects, the AAC system may be configured to generate acoustic control patterns, e.g., based on one or more of the primary patterns, such that, e.g., controlled sound zones, e.g., reduced noise zones, e.g., quiet zones, may be created by combinations of secondary and primary patterns, e.g., as described below.

[0018] In some demonstrative aspects, the AAC system may be configured to control, reduce and / or eliminate noise within predefined locations, areas or zones (also called "acoustic control zones," "noise control zones," "quiet zones," or "Quiet Bubbles®"), for example, as described below.

[0019] In some demonstrative aspects, the AAC system may be configured to control, reduce, and / or eliminate noise within an acoustic control zone without even a priori information regarding a primary pattern and / or one or more noise sources, e.g., regardless of and / or without the use thereof, as described below.

[0020] For example, the AAC system may be configured to control, reduce and / or eliminate noise within an acoustic control zone, e.g., independently of, regardless of, and / or without prior knowledge of, one or more attributes of one or more of the noise sources and / or one or more of the primary patterns, e.g., the number, type, location and / or other attributes of one or more of the primary patterns and / or one or more of the noise sources, e.g., as described below.

[0021] Some illustrative aspects are described herein with respect to AAC systems and / or methods configured to reduce and / or eliminate noise energy and / or wave amplitude of one or more acoustic patterns within a quiet zone, e.g., as described below.

[0022] However, in other aspects, any other AAC system and / or sound control system and / or method may be configured to control in any other manner any other sound energy and / or wave amplitude of one or more sound patterns within a sound control zone (sound control zone), e.g., to affect, change and / or modify the sound energy and / or wave amplitude of one or more sound patterns within a predefined zone, e.g., as described below.

[0023] In one example, an AAC system and / or method may be configured to selectively reduce and / or eliminate one or more types of acoustic energy and / or wave amplitude of an acoustic pattern within an acoustic control zone, and / or selectively increase and / or amplify one or more other types of acoustic energy and / or wave amplitude of an acoustic pattern within an acoustic control zone; and / or selectively preserve and / or maintain one or more types of acoustic energy and / or wave amplitude of an acoustic pattern within an acoustic control zone, e.g., as described below.

[0024] In some demonstrative aspects, the AAC system may be configured as and / or may execute one or more functions of a sound control system, e.g., a personal sound control system (also referred to as a “Personal Sound Bubble (PSB)® system”), which may be configured to generate sound control patterns that may be based on at least one voice input, such that, e.g., at least one personal sound zone may be created based on the voice input, as described below.

[0025] In some demonstrative aspects, the AAC system may be configured to control sounds within at least one predefined location, region or zone, e.g., at least one PSB, based on, e.g., sounds heard by a user. In one example, the PSB may be configured to include, e.g., a region around the user's head and / or ears, as described below.

[0026] In some demonstrative aspects, the AAC system may be configured to control a sound contrast, e.g., a difference, between one or more first sound patterns and one or more second sound patterns within a PSB, e.g., as described below.

[0027] In some demonstrative aspects, for example, an AAC system may be configured to control a sound contrast between one or more first sound patterns and one or more second sound patterns of a speech heard by a user, e.g., as described below.

[0028] In some demonstrative aspects, for example, the AAC system may be configured to selectively increase and / or amplify one or more types of sound energy and / or wave amplitude of the sound patterns within the PSB based, e.g., on sounds heard within the PSB; to selectively reduce and / or eliminate one or more types of sound energy and / or wave amplitude of the sound patterns within the PSB based, e.g., on the sound signals that are reduced and / or eliminated; and / or selectively preserve and / or maintain one or more other types of sound energy and / or wave amplitude of the sound patterns within the PSB, e.g., as described below.

[0029] In some demonstrative aspects, the AAC system may be configured to control sounds within the PSB based on any other additional or alternative inputs or criteria.

[0030] In some demonstrative embodiments, the AAC system can be configured to control, reduce, and / or eliminate one or more acoustic energy and / or wave amplitudes of a primary pattern within an acoustic control zone.

[0031] In some demonstrative aspects, the AAC system may be configured to control, reduce, and / or eliminate noise within an acoustic control zone in a selective and / or configurable manner, e.g., based on one or more predefined noise pattern attributes, e.g., as described below, so that, for example, the noise energy, wave amplitude, phase, frequency, direction and / or statistical characteristics of one or more first primary patterns may be influenced by a secondary pattern, but the secondary pattern may have only a reduced effect or no effect at all on the noise energy, wave amplitude, phase, frequency, direction and / or statistical characteristics of one or more second primary patterns.

[0032] In some demonstrative aspects, the AAC system may be configured to control, reduce, and / or eliminate acoustic energy and / or wave amplitude of a primary pattern on a predefined envelope or enclosure surrounding and / or enclosing the acoustic control zone, and / or at one or more predefined locations within the acoustic control zone.

[0033] In one example, an acoustic control zone may include a two-dimensional zone, for example, defining an area where one or more acoustic energy and / or wave amplitudes of a primary pattern are controlled, reduced, and / or eliminated.

[0034] According to this example, the AAC system may be configured to control, reduce and / or eliminate acoustic energy and / or wave amplitude of a primary pattern along a perimeter surrounding the acoustic control zone and / or at one or more predefined locations within the acoustic control zone.

[0035] In one example, the acoustic control zone may include a three-dimensional zone, e.g., defining a volume in which one or more acoustic energy and / or wave amplitudes of a primary pattern are controlled, reduced, and / or eliminated. In accordance with this example, the AAC system may be configured to control, reduce, and / or eliminate the acoustic energy and / or wave amplitudes of the primary pattern on surfaces surrounding the three-dimensional volume.

[0036] In one example, the acoustic control zone may include a spherical volume, and the AAC system may be configured to control, reduce and / or eliminate acoustic energy and / or wave amplitude of a primary pattern on a surface of the spherical volume.

[0037] In another example, the acoustic control zone may include a cubic volume and the AAC system may be configured to control, reduce and / or eliminate acoustic energy and / or wave amplitude of a primary pattern on a surface of the cubic volume.

[0038] In other embodiments, an acoustic control zone may include any other suitable volume that may be defined, for example, based on one or more attributes of the location in which the acoustic control zone is maintained.

[0039] Reference is now made to FIG. 1, which illustrates a schematic of an AAC system 100, in accordance with some demonstrative aspects.

[0040] Reference is also made to Figure 2, which illustrates, in accordance with some demonstrative aspects, a deployment scheme of components of an AAC system. For example, the deployment scheme 200 may include a deployment of one or more elements of the AAC system 100 of Figure 1.

[0041] In some demonstrative aspects, the AAC system 100 may include, operate as, and / or perform the functions of an active noise cancellation (ANC) system, an acoustic control system, and / or a sound control system, for example, as described below.

[0042] In some demonstrative aspects, the AAC system 100 may include a controller 102 (also referred to as an "AAC controller") for controlling sound within at least one AAC zone (also referred to as a "sound control zone" or "acoustic control zone") 110, for example, as described below.

[0043] In some demonstrative aspects, the controller 102 may include or be partially or fully implemented by circuitry and / or logic, e.g., one or more processors including circuitry and / or logic, and / or memory circuitry and / or logic. Additionally or alternatively, one or more functions of the radar controller 102 may be implemented by logic, which may be executed by a machine and / or one or more processors, e.g., as described below.

[0044] In one example, the controller 102 may include at least one memory 198, e.g., coupled to the one or more processors, that may be configured to store, e.g., at least a portion of the information processed by the one or more processors and / or circuitry, and / or to store logic utilized by the processors and / or circuitry.

[0045] In one example, at least a portion of the functionality of the controller 102 may be implemented by an integrated circuit, eg, a chip, eg, a system on a chip (SoC).

[0046] In other aspects, the controller 102 may be implemented with any other logic and / or circuitry and / or according to any other architecture.

[0047] In some illustrative embodiments, the AAC zone 110 may include an enclosed space, for example, as described below.

[0048] In some illustrative aspects, the sound control zone 110 may be located inside a vehicle and the AAC system 100 may be deployed as part of the vehicle. In other aspects, the sound control zone 110 may be located in any non-vehicle area or location.

[0049] In some illustrative aspects, the enclosed space may include, for example, a cabin of a vehicle, such as a car, a bus, and / or a truck, as described below.

[0050] In some demonstrative aspects, the enclosed space may include any other cabin, for example, an aircraft cabin, a train passenger compartment, a cabin of a medical system, an area of ​​a room, and the like.

[0051] In some demonstrative embodiments, the AAC zone 110 may include the space around one or more ears of a user.

[0052] In one example, the AAC system may be implemented as part of a headphone or earphone to control sound within an AAC zone 110, which may be defined, for example, around the ear of a user of the headphone or earphone.

[0053] In one example, the AAC system may be implemented as part of a piece of furniture, such as a chair, sofa, bed, headrest, or the like, to control sounds within an AAC zone 110, which may be defined, for example, around the ears of a user of the furniture.

[0054] In other aspects, the enclosed space may include any other enclosed portion or area of ​​a space, e.g., a vehicle or non-vehicle.

[0055] In some illustrative embodiments, the sound control zone 110 may include a three-dimensional (3D) zone. For example, the sound control zone 110 may include a spherical zone.

[0056] In some demonstrative aspects, AAC system 100 may be configured to control sounds and / or noises within zone 110 to provide an improved driving experience for the driver and / or one or more passengers of the vehicle, e.g., by controlling sounds and / or noises within zone 110 in a manner that provides an improved music and / or sound experience in the vehicle, improved quality telephone calls, and / or the like.

[0057] In some demonstrative aspects, the AAC controller 102 may include or be implemented with an input 191, which may be configured to receive input information 195, for example, as described below.

[0058] In some demonstrative aspects, the AAC controller 102 may include a controller 193 configured to determine, e.g., based on input information 195, a sound control pattern for controlling sound within at least one sound control zone 110, e.g., as described below.

[0059] In some demonstrative aspects, the input information 195 may include multiple noise inputs 104 from one or more acoustic sensors (also referred to as “primary sensors,” “noise sensors,” or “reference sensors”) 119 representing acoustic noise at multiple pre-defined noise detection locations 105, for example, as described below.

[0060] In some demonstrative aspects, the AAC controller 102 may receive the noise input 104 from one or more acoustic sensors 119, for example, as described below, which may include one or more physical sensors, such as microphones, accelerometers, tachometers, and the like, located at one or more of the locations 105, and / or one or more virtual sensors configured to estimate the acoustic noise at one or more of the locations 105.

[0061] In some demonstrative aspects, the input information 195 may include a plurality of residual noise inputs 106 from one or more residual noise acoustic sensors (also referred to as “error sensors,” “monitoring sensors,” or “secondary sensors”) 121 representing acoustic residual noise at a plurality of predefined residual noise detection locations 107 located within the sound control zone 110, for example, as described below.

[0062] In some demonstrative aspects, the AAC controller 102 may receive residual noise input 106 from one or more acoustic sensors 121, for example, as described below, which may include one or more physical sensors, such as microphones, accelerometers, tachometers, and / or the like, located at one or more of the locations 107, and / or one or more virtual sensors configured to estimate the residual noise at one or more of the locations 107.

[0063] In some demonstrative aspects, the AAC controller 102 may include at least one acoustic transducer 108, such as a speaker, a shaker, and / or any other actuator. For example, the AAC controller 102 may control the acoustic transducer 108 to generate acoustic sound control patterns configured to control sounds within sound control zones 110, e.g., as described in more detail below.

[0064] In one example, the noise input 104 may represent the noise to be controlled, eg, reduced and / or canceled, within the sound control zone 110 .

[0065] In one example, the residual noise input 106 may represent residual noise at one or more locations 107 within the sound control zone 110. For example, the residual noise input 106 may represent a portion of the residual noise, e.g., noise outside the sound control zone 110, e.g., based on a sound control pattern.

[0066] In some demonstrative aspects, the at least one acoustic transducer 108 may include, for example, an array of one or more acoustic transducers, e.g., at least one suitable speaker, to generate a sound control pattern based on the sound control signal 109.

[0067] In some demonstrative embodiments, at least one acoustic transducer 108 may be positioned at one or more locations, which may be determined based on one or more attributes of the sound control zone 110, such as the size and / or shape of the zone 110, one or more expected attributes input 104, one or more expected attributes of one or more potential actual noise sources 202, such as the expected location and / or directionality of the noise sensor 202 relative to the sound control zone 110, the number of noise sources 202, and the like.

[0068] In one example, the acoustic transducer 108 may include a speaker array including a predefined number of speakers, denoted as M, or a multi-channel acoustic source. In some demonstrative embodiments, the acoustic transducer 108 may include an array of speakers implemented using a suitable "compact acoustic source" positioned in a suitable location, e.g., outside the zone 110.

[0069] In another example, a speaker array may be implemented using multiple speakers distributed within a space, for example around the sound control zone 110.

[0070] In some demonstrative embodiments, one or more of the locations 105 may be distributed in any combination of locations on the spherical volume and / or outside the spherical volume, e.g., one or more locations around the spherical volume, e.g., as described below.

[0071] In some demonstrative embodiments, one or more of the locations 105 may be distributed outside of the sound control zone 110. For example, one or more of the locations 105 may be distributed on or in proximity to an envelope or enclosure that surrounds the sound control zone 110.

[0072] For example, if the sound control zone 110 is defined by a spherical volume, one or more of the locations 105 may be distributed on the surface of the spherical volume and / or on the exterior of the spherical volume.

[0073] In some demonstrative embodiments, the locations 107 may be distributed within the sound control zone 110, for example, proximate to the envelope of the sound control zone 110.

[0074] For example, if the zone 110 is defined by a spherical volume, the locations 107 may be distributed on a sphere having a radius that is smaller than the radius of the sound control zone 110 .

[0075] In some demonstrative aspects, the AAC system 100 may include one or more first acoustic sensors (“primary sensors”) 119 to detect acoustic noise at one or more of the plurality of noise detection locations 105.

[0076] In some demonstrative aspects, the AAC system 100 may include one or more second acoustic sensors (“error sensors” or “monitoring sensors”) 121 to detect acoustic residual noise at one or more of the multiple residual noise detection locations 107.

[0077] In some demonstrative aspects, one or more of the error sensors and / or one or more of the primary sensors may be implemented using one or more "virtual sensors" ("virtual microphones"). A virtual microphone corresponding to a particular microphone location may be implemented by any suitable algorithm and / or method capable of evaluating an acoustic pattern that may have been sensed by an actual acoustic sensor located at the particular microphone location.

[0078] In some demonstrative aspects, the AAC controller 102 may be configured to simulate and / or perform the function of a virtual microphone, for example, by estimating and / or evaluating an acoustic noise pattern at a particular position of the virtual microphone.

[0079] In some demonstrative aspects, the AAC system, e.g., AAC system 100 (FIG. 1), may include a first array 219 of one or more primary sensors, e.g., microphones, accelerometers, tachometers, and the like, configured to detect a primary pattern at one or more of the locations 105. For example, the array 219 may include a plurality of acoustic sensors 119 (FIG. 1). For example, the array 219 may include a microphone to output a noise signal 104 (FIG. 1) including, e.g., a sequence of N samples per second. For example, N may be, e.g., 48000 samples per second if the microphone operates at a sampling rate of about 48 KHz. The noise signal 104 (FIG. 1) may include any other suitable signal having any other suitable sampling rate and / or any other suitable attributes.

[0080] In some demonstrative aspects, one or more of the sensors of the array 219 may be implemented using one or more “virtual sensors.” For example, the array 219 may be implemented by a combination of at least one microphone and at least one virtual microphone. A virtual microphone corresponding to a particular microphone position of the location 105 may be implemented as part of the controller 102 ( FIG. 1 ) or any other element of the system 100 ( FIG. 1 ) capable of evaluating an acoustic pattern, e.g., as sensed by an acoustic sensor disposed at the particular microphone position, by any suitable algorithm and / or method. For example, the controller 102 ( FIG. 1 ) may be configured to evaluate the acoustic pattern of the virtual microphone based on at least one actual acoustic pattern sensed by at least one microphone 119 ( FIG. 1 ) of the array 219.

[0081] In some demonstrative aspects, the AAC system 100 (FIG. 1) may include a second array 221 of one or more error sensors, e.g., microphones, configured to detect acoustic residual noise at one or more of the locations 107. For example, the array 221 may include a plurality of acoustic sensors 121 (FIG. 1). For example, the error sensor may include one or more sensors to detect a spherical acoustic residual noise pattern within the spherical sound control zone 110.

[0082] In some demonstrative aspects, one or more of the sensors of the array 221 may be implemented using one or more “virtual sensors.” For example, the array 221 may include a combination of at least one microphone and at least one virtual microphone. A virtual microphone corresponding to a particular microphone position of the location 107 may be implemented as part of the controller 102 ( FIG. 1 ) or any other element of the system 100 ( FIG. 1 ) capable of evaluating an acoustic pattern, e.g., as sensed by an acoustic sensor disposed at the particular microphone position, by any suitable algorithm and / or method. For example, the controller 102 ( FIG. 1 ) may be configured to evaluate the acoustic pattern of the virtual microphone based on at least one actual acoustic pattern sensed by at least one microphone 121 ( FIG. 1 ) of the array 221.

[0083] In some demonstrative embodiments, the number, location and / or distribution of locations 105 and / or 107, and / or the number, location and / or distribution of one or more acoustic sensors at one or more of locations 105 and 107 may be determined based on the size of sound control zone 110 and / or the envelope of sound control zone 110, the shape of sound control zone 110 or the envelope of sound control zone 110, one or more attributes of the acoustic sensors located at one or more of locations 105 and / or 107, e.g., the sampling rate of the sensors, and the like.

[0084] In one example, one or more acoustic sensors, such as microphones, accelerometers, tachometers, and the like, may be deployed at locations 105 and / or 107 according to the spatial sampling theorem, for example, as defined by Equation 1 below.

[0085] For example, the number of primary sensors, the distance between the primary sensors, the number of error sensors and / or the distance between the error sensors may be determined according to the spatial sampling theorem, for example, as defined by Equation 1 below.

[0086] In one example, the primary sensors and / or error sensors may be distributed, e.g., evenly or non-evenly, at a distance, denoted d, from one another. For example, the distance d may be determined as follows:

number

[0087] For example, if the maximum frequency of interest is f max = 100 [Hz], the distance d is

number

[0088] 2, the deployment scheme 200 may be configured with respect to a circular or spherical sound control zone 110. For example, one or more locations 105 are distributed, e.g., substantially evenly distributed, in a spherical or annular fashion around the sound control zone 110, and locations 107 are distributed, e.g., substantially evenly distributed, in a spherical or annular fashion within the sound control zone 110.

[0089] However, in other aspects, the components of AAC system 100 may be deployed according to any other deployment scheme including, for example, any suitable distribution of locations 105 and / or 107 configured with respect to sound control zones of any other suitable shape and / or configuration.

[0090] In some demonstrative aspects, the AAC controller 102 may be configured to determine a sound control pattern within the sound control zone 110 to be reduced according to at least one noise parameter, e.g., energy, amplitude, phase, frequency, direction, and / or statistical characteristics, as described in detail below.

[0091] In some demonstrative aspects, the AAC controller 102 may determine a sound control pattern, for example, to selectively reduce one or more predefined first noise patterns within the sound control zone 110 while not reducing one or more second noise patterns within the sound control zone 110, as described below.

[0092] In some demonstrative aspects, the sound control zone 110 may be located within the interior of the vehicle, and the AAC controller 102 may determine the sound control pattern to selectively reduce one or more first noise patterns including, for example, a traffic noise pattern, a wind noise pattern, and / or an engine noise pattern, without reducing one or more second noise patterns including, for example, an audio noise pattern of an audio device located within the vehicle, a horn noise pattern, a siren noise pattern, a hazard noise pattern of a hazard, an alarm noise pattern of an alarm signal, an information signal noise pattern, and the like.

[0093] In other aspects, the sound control zone 110 may be in any other location and / or area, e.g., within a vehicle or non-vehicle, and the AAC controller 102 may be configured to determine the sound control pattern to selectively reduce any other one or more first noise patterns while not reducing any other one or more second noise patterns.

[0094] In some demonstrative aspects, the AAC controller 102 may determine a sound control pattern without even having information regarding one or more noise source attributes of, for example, one or more actual noise sources 202 causing acoustic noise at the noise detection location 105.

[0095] For example, the noise source attributes may include the number of noise sources 202 , the locations of the noise sources 202 , the types of noise sources 202 and / or one or more attributes of one or more noise patterns generated by one or more of the noise sources 202 .

[0096] In some demonstrative aspects, the AAC controller 102 may be configured to determine the sound control pattern while taking into account one or more factors, e.g., one or more acoustic transfer functions between elements of the AAC system 100, e.g., the acoustic transfer function between at least one acoustic transducer 108 and one or more residual noise sensors 121; and / or statistical characteristics of the noise addressed by the AAC system 100, e.g., as described below.

[0097] In some demonstrative aspects, the AAC controller 102 may be configured to generate the sound control pattern 109 based on the voice and / or audio signals heard within the sound control zone 110, for example, as described below.

[0098] In some demonstrative aspects, the input information 195 may include a voice and / or audio signal 133 from a voice / audio source 131 .

[0099] In one example, the voice and / or audio signal 133 may include audio and / or voice signals heard within the sound control zone 110, such as music, speech, calls, or the like.

[0100] In some demonstrative aspects, the AAC controller 102 may be configured to generate the sound control pattern 109 based on the voice and / or audio signal 133, for example, as described below.

[0101] In other aspects, the AAC controller 102 may be configured to determine the sound control pattern 109 based on any additional or alternative factors, criteria, attributes, and / or parameters.

[0102] In some demonstrative aspects, the AAC controller 102 may include an acoustic feedback (AFB) mitigator 150 (also referred to as an “AFB controller,” “AFB canceller,” “feedback canceller (FBC),” “echo mitigator,” or “echo canceller”) that may be configured to mitigate AFB between the acoustic transducer 108 and one or more acoustic sensors of the AAC system 100, for example, as described below.

[0103] In one example, the AFB mitigator 150 may be configured to mitigate AFB between one or more acoustic transducers 108 and one or more of the reference noise acoustic sensors 119, for example, as described below.

[0104] In another example, the AFB mitigator 150 may be configured to mitigate AFB between one or more acoustic transducers 108 and one or more of the residual noise sensors 121, for example, as described below.

[0105] Some illustrative aspects are described herein with respect to an AFB mitigator, e.g., AFB mitigator 150, implemented by a controller, e.g., controller 102, of an AAC system, e.g., AAC system 100. However, in other aspects, the AFB mitigator, e.g., AFB mitigator 150, may be implemented as part of a controller of any other additional or alternative types of devices and / or systems.

[0106] In some demonstrative aspects, for example, it may be necessary to provide technical solutions to mitigate AFB that may not be constant in some use cases, scenarios, deployments, and / or implementations ("non-constant AFB").

[0107] For example, the acoustic medium between an acoustic transducer of the AAC system, e.g., acoustic transducer 108, and an acoustic sensor of the AAC system, e.g., reference noise sensor 119 and / or residual noise sensor 121, may not be fixed or constant.

[0108] In one example, the acoustic medium between an acoustic transducer of the AAC system, e.g., acoustic transducer 108, and an acoustic sensor of the AAC system, e.g., reference noise sensor 119 and / or residual noise sensor 121, may change, for example, based on changes in the environment of the AAC system, e.g., temperature, humidity, or the like.

[0109] In another example, the acoustic medium between an acoustic transducer of the AAC system, e.g., acoustic transducer 108, and an acoustic sensor of the AAC system, e.g., reference noise sensor 119 and / or residual noise sensor 121, may change, for example, based on changes in the physical locations of and / or the distance between the acoustic transducers and / or acoustic sensors.

[0110] In some demonstrative aspects, for example, in some use cases, scenarios, deployments, and / or implementations, it may be necessary to provide a technical solution to implement an adaptive AFB mitigator, e.g., to mitigate non-constant AFB, where an implementation using a fixed AFB mitigator may not be suitable for providing sufficient results.

[0111] In some demonstrative aspects, AFB mitigator 150 may be configured as an adaptive AFB mitigator, for example, as described below.

[0112] In some demonstrative aspects, the AFB mitigator 150 may be configured to adapt to changes in the acoustic medium between an acoustic transducer of the AAC system 100, e.g., acoustic transducer 108, and an acoustic sensor of the AAC system 100, e.g., reference noise sensor 119, for example, as described below.

[0113] In some demonstrative aspects, AFB mitigator 150 may utilize at least one adaptive filter that may be configured to adapt to changes in the acoustic medium, for example, as described below.

[0114] In some demonstrative aspects, the adaptive filter may include a finite impulse response (FIR) filter, for example, as described below.

[0115] In one example, a filter response, denoted as h, e.g.

number

number

[0116] In some demonstrative aspects, the adaptive filter may include an infinite impulse response (IIR) filter, for example, as described below.

[0117] In one example, an IIR filter having a filter function based on coefficients, denoted a and b, is applied to an input signal, denoted x, e.g., x=[x n-N ,x n-(N-1) ,..,x n ] to produce an output (the "filtered signal"), denoted as y, e.g.

number

[0118] In other aspects, any other additional or alternative types of adaptive filters may be used.

[0119] In some demonstrative aspects, AFB mitigator 150 may utilize a least mean squares (LMS) algorithm to adapt one or more parameters of AFB mitigator 150, for example, as described below.

[0120] In some demonstrative aspects, the AFB mitigator 150 may adapt one or more parameters of the AFB mitigator 150 based on an LMS algorithm and / or an LMS algorithm variant, such as normalized LMS (NLMS), leaky LMS, and / or any other LMS variant.

[0121] In other aspects, any other additional or alternative adaptive algorithms may be utilized.

[0122] In some demonstrative aspects, the AFB mitigator 150 may be configured to provide technical solutions to support implementation of an adaptive AFB mitigator utilizing an LMS algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant, e.g., as described below.

[0123] For example, when implementing some LMS algorithms, there may be a requirement that the desired signal at the output of the filter and the input of the filter be uncorrelated, for example, to achieve convergence.

[0124] In some demonstrative aspects, for example, there may be a need for a technical solution to support implementation of an ANC system that utilizes adaptive FBC even when the acoustic transducer (loudspeaker) output and the reference sensor (microphone) are correlated, e.g., even highly correlated.

[0125] In some demonstrative aspects, the AFB mitigator 150 may be configured to adapt to changes in the acoustic medium between an acoustic transducer of the AAC system 100, e.g., acoustic transducer 108, and an acoustic sensor of the AAC system 100, e.g., reference noise sensor 119 and / or residual noise sensor 121, even if the output of the acoustic transducer 108 and the input to the acoustic sensor, e.g., reference noise sensor 119 and / or residual noise sensor 121, are correlated, for example, as described below.

[0126] In some demonstrative aspects, the AFB mitigator 150 may include a first filter 152 configured to generate a first filtered signal, e.g., by filtering a first input signal, e.g., as described below.

[0127] In some demonstrative aspects, the first input signal may be based on a first acoustic pattern (a "transducer acoustic pattern"), e.g., a sound control pattern, e.g., sound control pattern 109, output by an acoustic transducer 108, e.g., as described below.

[0128] In some demonstrative aspects, the first filter 152 may be configured to generate the first filtered signal, e.g., by filtering the first input signal, e.g., according to and / or based on a first filter function, e.g., as described below.

[0129] In some demonstrative aspects, the AFB mitigator 150 may include a second filter 154 configured to generate a second filtered signal, e.g., by filtering the first input signal, e.g., according to and / or based on a second filter function, e.g., as described below.

[0130] In some demonstrative aspects, the second filter 154 may include an adaptive filter, for example, as described below.

[0131] In some demonstrative aspects, the second filter 154 may be adapted based on, for example, a difference between the AFB mitigated signal and the second filtered signal, e.g., as described below.

[0132] In some demonstrative aspects, the AFB mitigated signal may be based on a difference between the second input signal and the first filtered signal, for example, as described below.

[0133] In some demonstrative aspects, the second input signal may be based on a second acoustic pattern (a “sensor acoustic pattern”), e.g., acoustic noise detected by acoustic sensor 119 and / or residual noise sensor 121, which may be detected by an acoustic sensor, for example, as described below.

[0134] In some demonstrative aspects, the first filter 152 may be configured to generate a first filtered signal including a first estimate of the AFB, e.g., between the acoustic transducer 108 and an acoustic sensor, e.g., the reference noise sensor 119 and / or the residual noise sensor 121, e.g., as described below.

[0135] In some demonstrative aspects, the second filter 154 may be configured to generate a second filtered signal including a second estimate of the AFB, e.g., between the acoustic transducer 108 and an acoustic sensor, e.g., the reference noise sensor 119 and / or the residual noise sensor 121, e.g., as described below.

[0136] In some demonstrative aspects, the second filter 154 may be configured to generate a second filtered signal based on a change in the AFB, e.g., between the acoustic transducer 108 and an acoustic sensor, e.g., the reference noise sensor 119 and / or the residual noise sensor 121, e.g., as described below.

[0137] In some demonstrative aspects, the controller 193 may include a predictive filter (PF) 156, for example, as described below.

[0138] In some demonstrative aspects, PF 156 may be configured to generate a PF output, eg, based on a PF input, eg, as described below.

[0139] In some demonstrative embodiments, the PF 156 may be configured to generate a PF output based on, for example, a PF input and an acoustic configuration between the acoustic transducer 108 and the sound control zone 110, for example, as described below. In other embodiments, the PF 156 may be configured to generate a PF output based on any other additional or alternative parameters and / or criteria.

[0140] In some demonstrative aspects, the PF input of PF 156 may be based on an AFB mitigated signal provided by AFB mitigator 150, for example, as described below.

[0141] In some demonstrative aspects, the sound control pattern 109 may be based on the PF output of the PF 156.

[0142] In some demonstrative embodiments, the sound control pattern 109 may be based on a combination of the PF output of the PF 156 and at least one of an audio signal and / or a voice signal heard within the sound control zone 110, for example.

[0143] In some embodiments, the sound control pattern 109 may be based directly on the PF output of the PF 156 or may include only the PF output of the PF 156.

[0144] In other embodiments, the sound control pattern 109 may be based on any other combination of the PF output of the PF 156 and any other audio and / or sound patterns or signals.

[0145] In some demonstrative aspects, the second filter 154 may be adapted based on a least mean squares (LMS) algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant, for example, as described below.

[0146] In other aspects, the second filter 154 may be adapted based on any other additional or alternative adaptive algorithms.

[0147] In some demonstrative aspects, at least one of the first filter 152 and / or the second filter 154 may include an FIR filter, for example, as described below.

[0148] In some demonstrative aspects, at least one of the first filter 152 and / or the second filter 154 may include an IIR filter, for example, as described below.

[0149] In other aspects, any other type of filter may be utilized by filter 152 and / or filter 154.

[0150] In some demonstrative aspects, the first filter 152 may include a fixed filter having a fixed filter function, for example, as described below.

[0151] In some demonstrative aspects, the fixed filter function of filter 152 may be based on a predefined acoustic configuration between acoustic transducer 108 and an acoustic sensor, such as reference noise sensor 119 and / or residual noise sensor 121, for example, as described below.

[0152] In some demonstrative aspects, AFB mitigator 150 may be configured to support technical solutions that enable the use of a filter, e.g., filter 152, that may be different from a filter, e.g., filter 154, that may be utilized by an adaptation block of AFB mitigator 150, e.g., as described below.

[0153] In some demonstrative aspects, the filter length of filter 152 may differ from the filter length of filter 154.

[0154] In one example, the filter length of filter 152 may be longer than the filter length of filter 154 .

[0155] In another example, the filter length of filter 152 may be less than the filter length of filter 154 .

[0156] In other embodiments, filters 152 and 154 may have the same filter length.

[0157] In some demonstrative aspects, the filter architecture of filter 152 may differ from the filter architecture of filter 154.

[0158] In other aspects, filter 152 and filter 154 may have the same filter architecture.

[0159] In some demonstrative aspects, implementation of filter 152 using a fixed filter may provide a technical solution, e.g., in terms of reduced memory, processing, and / or complexity. For example, filter adaptation may consume more memory and / or processing resources as compared to, e.g., a fixed filtering process.

[0160] In some demonstrative aspects, for example, in some implementations and / or use cases, filter 152 may be configured to utilize a relatively long fixed filter, e.g., compared to the length of filter 154, e.g., to better represent a predefined filter. For example, the fixed filter may be "fine-tuned," e.g., using filter 154 configured to have a lower filter order and / or a different architecture. For example, this implementation may provide a technical solution for reducing processing and / or memory needs for the adaptation block. Accordingly, this implementation may provide a technical solution for resulting in improved overall system processing and / or memory needs.

[0161] In some demonstrative aspects, for example, in some implementations and / or use cases, the filter 152 may be configured to utilize a relatively short fixed filter, e.g., compared to the length of the filter 154. For example, the implementation of a relatively short fixed filter 152 may be suitable for a relatively narrow band ANC system, e.g., with a bandwidth up to 300hz, and / or any other suitable AAC implementation. For example, this implementation may provide a technical solution that utilizes a relatively short, e.g., low-cost, fixed filter 152. For example, a higher order or more complex / expensive filter architecture may be utilized for the filter 154 of the adaptation block. In one example, the filter 154 may include a higher order FIR, e.g., compared to a short order IIR and / or a second order digital IIR (biquad).

[0162] In some demonstrative aspects, AFB mitigator 150 may be configured to utilize filters 152 and 154 to provide a technical solution to support feedback canceller estimation to two filter stages, for example, as described below.

[0163] In some demonstrative aspects, the filter 152 may be implemented using a fixed filter that may be calibrated and / or pre-tuned, for example, during a calibration process, with respect to a predefined acoustic configuration between the acoustic transducer 108 and an acoustic sensor, e.g., the reference noise sensor 119 and / or the residual noise sensor 121.

[0164] In one example, filter 152 may be implemented using an IIR, for example, having a length on the order of (2-20).

[0165] In another example, filter 152 may be implemented using cascaded IIRs, for example 1 to 10 cascaded biquads.

[0166] In another example, the filter 152 may be implemented using an FIR filter, for example, having a length on the order of (10-1000).

[0167] In other aspects, the filter 152 may be implemented using any other type of filter.

[0168] In some demonstrative aspects, filter 154 may be implemented using an adaptive filter configured to continually adapt to changes in acoustic feedback, for example, as described below.

[0169] In some demonstrative aspects, filter 154 may be implemented using a short adaptive filter, eg, a short adaptive FIR filter, for example, having a length on the order of (10-100).

[0170] In one example, the filter 154 may be adapted for a predefined period of time, for example, 1-120 seconds or any other period of time, followed by freezing the adaptation.

[0171] In other aspects, the filter 154 may be implemented using any other type of adaptive filter.

[0172] Reference is made to Fig. 3, which illustrates a schematic of an adaptive AFB mitigator 350 implemented within an AAC system in accordance with some demonstrative aspects. For example, AFB mitigator 150 (Fig. 1) may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 350.

[0173] In some demonstrative aspects, the AFB mitigator 350 may be configured to mitigate acoustic feedback 360 between the acoustic transducer 308 and an acoustic sensor 319, such as a reference noise sensor and / or an error noise sensor in an AAC system, for example, as described below. In one example, the acoustic transducer 308 may include the acoustic transducer 108 (FIG. 1), and / or the acoustic sensor 319 may include the reference noise sensor 119 (FIG. 1) or the residual noise sensor 121 (FIG. 1).

[0174] In other aspects, one or more, e.g., some or all, of AFB mitigator 350 may be implemented by and / or configured to mitigate acoustic feedback for any other device and / or system, e.g., as described below.

[0175] In some demonstrative aspects, the AFB mitigator 350 may include a first filter 352 configured to generate a first filtered signal 363 by filtering a first input signal 361, e.g., according to and / or based on a first filter function, e.g., as described below.

[0176] In some demonstrative aspects, the first input signal 361 may be based on a transducer acoustic pattern output by the acoustic transducer 308, for example, as described below.

[0177] In some demonstrative aspects, the first input signal 361 may be based on a sound control pattern output by the acoustic transducer 308, for example, as described below.

[0178] In other aspects, the first input signal 361 may be based on any other type of transducer acoustic pattern output by the transducer 308. In one example, the first input signal 361 may be based on or include an audio signal output by the transducer 308.

[0179] In some demonstrative aspects, the AAC system may include a PF 376 that may be configured to generate a PF output 377 based on a PF input 375 .

[0180] In some demonstrative aspects, the PF 376 may be configured to generate the PF output 377 based on, for example, the PF input 375 and the acoustic configuration between the acoustic transducer 308 and an acoustic control zone of the AAC system, such as acoustic control zone 110 (FIG. 2). In other aspects, the PF 376 may be configured to generate the PF output 377 based on any other additional or alternative parameters and / or criteria.

[0181] In some demonstrative aspects, the sound control pattern output by the acoustic transducer 308 may be based on the PF output 377.

[0182] In some demonstrative aspects, the first input signal 361 may be based on the PF output 377 .

[0183] In some demonstrative aspects, the first input signal 361 may include a PF output 377, for example, as described below.

[0184] In other aspects, the first input signal 361 may be based on the PF output 377 and one or more audio and / or voice signals, for example, as described below.

[0185] In some demonstrative aspects, the AFB mitigator 350 may include a second filter 354 configured to generate a second filtered signal 381 by filtering the first input signal 361, e.g., according to and / or based on a second filter function, e.g., as described below.

[0186] In some demonstrative aspects, the second filter 354 may include an adaptive filter, for example, as described below.

[0187] In some demonstrative aspects, the second filter 354 may be adapted based on, for example, a difference between the AFB mitigated signal 383 and the second filtered signal 381, e.g., as described below.

[0188] In some demonstrative aspects, the AFB mitigated signal 383 may be based on the difference between the second input signal 369 and the first filtered signal 363, for example, as described below.

[0189] In some demonstrative aspects, the second input signal 369 may be based on a sensor acoustic pattern sensed by the acoustic sensor 319, for example, as described below.

[0190] In some demonstrative aspects, the second input signal 369 may be based on acoustic noise detected by the acoustic sensor 319, for example, as described below.

[0191] In other aspects, the second input signal 369 may be based on any other type of transducer acoustic pattern sensed by the acoustic sensor 319. In one example, the second input signal 369 may be based on or include audio, voice, noise, or the like that may be sensed within the environment of the acoustic sensor 319.

[0192] In some demonstrative aspects, the first filter 352 may be configured to generate a first filtered signal 363 that includes a first estimate of the AFB 360, e.g., between the acoustic transducer 308 and the acoustic sensor 319, e.g., as described below.

[0193] In some demonstrative aspects, the second filter 354 may be configured to generate a second filtered signal 381 that includes a second estimate of the AFB 360, e.g., between the acoustic transducer 308 and the acoustic sensor 319, e.g., as described below.

[0194] In some demonstrative aspects, the second filter 354 may be configured to generate a second filtered signal 381 based on a change in the AFB 360, e.g., between the acoustic transducer 308 and the acoustic sensor 319, e.g., as described below.

[0195] In some demonstrative aspects, the first filter 352 may include a fixed filter having a fixed filter function, for example, as described below.

[0196] In some demonstrative aspects, the first filter 352 may include a fixed IIR filter, for example, as described below.

[0197] In other aspects, the first filter 352 may include a fixed FIR filter, or any other type of fixed filter.

[0198] In some demonstrative aspects, the fixed filter function of the filter 352 may be based on a predefined acoustic configuration between the acoustic transducer 308 and the acoustic sensor 319, for example.

[0199] In some demonstrative aspects, the AFB mitigator 350 may include a first subtractor 391 for generating the first AFB mitigated signal 383, for example, by subtracting the first filtered signal 363 from the second input signal 369.

[0200] In some demonstrative aspects, the AFB mitigator 350 may include a second subtractor 392 for generating a second AFB mitigated signal 373 by subtracting the second filtered signal 381 from the first AFB mitigated signal 383.

[0201] In some demonstrative aspects, the second filter 354 may be adapted based on a difference between the first AFB mitigated signal 383 and the second filtered signal 381 .

[0202] In some demonstrative aspects, the PF input 375 may be based on the second AFB mitigated signal 373.

[0203] In some demonstrative aspects, the second filter 354 may be implemented by a short adaptive FIR filter, for example, as described below.

[0204] In other aspects, the second filter 354 may include any other adaptive FIR filter, an adaptive IIR filter, and / or any other adaptive filter.

[0205] In some demonstrative embodiments, the reference signal picked up by acoustic sensor 319, denoted as rmic1, is

number

number

[0206] In some demonstrative aspects, the response, e.g., the desired response, for adaptive filter 354, denoted as H, is:

number

number

number

number

number

number

number

number

[0207] According to the above definition and description, e H The residual error signal, denoted [n], may be determined, for example, as follows:

number

[0208] In some demonstrative aspects, the coefficients of the adaptive filter H may be adapted according to an LMS algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant, e.g., as described below. In other aspects, any other algorithm may be used.

[0209] In some demonstrative aspects, the coefficients of the adaptive filter H may be adapted according to an LMS algorithm, for example, as follows:

number

[0210] In some demonstrative aspects, a signal 373, denoted as x, at a PF input 375 of PF 376 may be determined, for example, as follows:

number

[0211] In some demonstrative aspects, when the adaptive filter H converges, the result is, for example,

number

[0212] Referring back to FIG. 1, in some demonstrative aspects, AFB mitigator 150 may be configured to support technical solutions that implement a signal (also referred to as a "virtual signal"), e.g., a predefined or preconfigured signal, that may be generated internally by AAC system 100, as described below.

[0213] In some demonstrative aspects, the AFB mitigator 150 may be configured to support technical solutions that utilize virtual signals in the process of adapting the adaptive filter 154, for example, as described below.

[0214] In some illustrative embodiments, there may be one or more technical problems and / or drawbacks in adding a white noise signal to the speaker output and using the white noise signal to adapt the AFB mitigator. For example, there may be one or more technical problems and / or drawbacks in injecting white noise into the output of the ANC system, since adding noise heard by the user may be undesirable. This would be in contrast to the concept of emitting an output based on phase noise resistance from the speaker of the AAC system to reduce undesirable noise. For example, if noise is added to the output of the speaker to adapt the feedback canceller in real time, the user may typically hear the added noise. This added noise may also result in ANC performance degradation, for example, enhancing the noise at the user's ear instead of reducing the noise heard at the ear position.

[0215] In some demonstrative aspects, the AFB mitigator 150 may be configured to support technical solutions that use an internally generated signal to enhance the performance of the AFB mitigator, e.g., as described below, without even adding a white noise signal to the loudspeaker output that can be heard by the user.

[0216] In some demonstrative aspects, the AFB mitigator 150 may be configured to support technical solutions that use internally generated signals to enhance the performance of the AFB mitigator, while avoiding technical problems associated with, for example, "playing" white noise.

[0217] In some demonstrative aspects, AFB mitigator 150 may be adapted based on an internally generated virtual signal, for example, as described below.

[0218] In some demonstrative aspects, the virtual signal may be used as an additional input to an adaptation block of AFB 150, for example, as described below.

[0219] In some demonstrative aspects, an estimate of the convolution of the virtual signal with the AFB may be added to the signal from the reference microphone 119, for example, as described below.

[0220] In some demonstrative aspects, the internally generated virtual signal may be configured as a noise signal, e.g., a white noise signal, or a pink noise signal. In one example, the internally generated virtual signal may be configured as a noise signal with one or more predefined frequency ranges and spectra, e.g., above 100hz, 200-100hz, and / or any other range used to further optimize the adaptation of the feedback canceller.

[0221] In other aspects, the internally generated virtual signal may be configured as any other pre-defined signal according to any other parameters and / or criteria.

[0222] In some demonstrative aspects, the first filter 152 may include an adaptive filter, for example, as described below.

[0223] In some demonstrative aspects, the virtual signal may be utilized to adapt the first filter 152, for example, as described below.

[0224] In some demonstrative aspects, the coefficients of filter 152 may be adapted based on a pre-defined, internally generated virtual signal, for example, as described below.

[0225] In some demonstrative aspects, the virtual signal may be configured to provide technical solutions to support further optimization of the AFB mitigator 150, e.g., with one or more frequency bands, in addition to adapting the filter 154.

[0226] For example, the virtual signal may support further optimization of the AFB mitigator 150 when the sound control pattern 109, e.g., signal y, used as an input to, e.g., filter 152 and / or filter 154, does not have and / or cover all frequency ranges and / or sufficient signal energy at those frequencies, for example, to reduce any acoustic feedback heard by the microphone from the speaker(s).

[0227] Reference is made to Fig. 4, which illustrates a schematic of an adaptive AFB mitigator 450 implemented within an AAC system in accordance with some demonstrative aspects. For example, AFB mitigator 150 (Fig. 1) may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 450.

[0228] In some demonstrative aspects, the AFB mitigator 450 may be configured to mitigate acoustic feedback 460 between the acoustic transducer 408 and an acoustic sensor 419, such as a reference noise sensor and / or an error noise sensor in an AAC system, e.g., as described below. In one example, the acoustic transducer 408 may include the acoustic transducer 108 (FIG. 1), and / or the acoustic sensor 419 may include the reference noise sensor 119 (FIG. 1) or the residual noise sensor 121 (FIG. 1).

[0229] In other aspects, one or more, e.g., some or all, of AFB mitigator 450 may be implemented by and / or configured to mitigate acoustic feedback for any other device and / or system, e.g., as described below.

[0230] In some demonstrative aspects, the AFB mitigator 450 may include a first filter 452 configured to generate a first filtered signal 463 by filtering a first input signal 461, e.g., according to and / or based on a first filter function, e.g., as described below.

[0231] In some demonstrative aspects, the first input signal 461 may be based on a transducer acoustic pattern output by the transducer 408, for example, as described below.

[0232] In some demonstrative aspects, the first input signal 461 may be based on a sound control pattern output by the acoustic transducer 408, for example, as described below.

[0233] In other aspects, the first input signal 461 may be based on any other type of transducer acoustic pattern output by the transducer 408. In one example, the first input signal 461 may be based on or include an acoustic signal output by the transducer 408.

[0234] In some demonstrative aspects, the AAC system may include a PF 476 that may be configured to generate a PF output 477 based on a PF input 475 .

[0235] In some demonstrative aspects, the PF 476 may be configured to generate the PF output 477 based on, for example, the PF input 475 and the acoustic configuration between the acoustic transducer 408 of the AAC system and a sound control zone, such as sound control zone 110 (FIG. 2). In other aspects, the PF 476 may be configured to generate the PF output 477 based on any other additional or alternative parameters and / or criteria.

[0236] In some demonstrative aspects, the sound control pattern output by the acoustic transducer 408 may be based on the PF output 477.

[0237] In some demonstrative aspects, the first input signal 461 may be based on the PF output 477 .

[0238] In some demonstrative aspects, the first input signal 461 may include a PF output 477, for example, as described below.

[0239] In other embodiments, the first input signal 461 may be based on the PF output 477 and one or more audio and / or speech signals, for example audio and / or speech signals heard within a sound control zone of an AAC system.

[0240] In some demonstrative aspects, the AFB mitigator 450 may include a second filter 454 configured to generate a second filtered signal 481, e.g., by filtering the first input signal 461, e.g., according to and / or based on a second filter function, e.g., as described below.

[0241] In some demonstrative aspects, the second filter 454 may include an adaptive filter, for example, as described below.

[0242] In some demonstrative aspects, the second filter 454 may be adapted based on, for example, a difference between the AFB mitigated signal 483 and the second filtered signal 481, e.g., as described below.

[0243] In some demonstrative aspects, the AFB mitigated signal 483 may be based on the difference between the second input signal 469 and the first filtered signal 463, for example, as described below.

[0244] In some demonstrative aspects, the second input signal 469 may be based on a sensor acoustic pattern sensed by the acoustic sensor 419, for example, as described below.

[0245] In some demonstrative aspects, the second input signal 369 may be based on acoustic noise detected by an acoustic sensor 419, for example, as described below.

[0246] In other embodiments, the second input signal 469 may be based on any other type of transducer acoustic pattern sensed by the acoustic sensor 419. In one example, the second input signal 469 may be based on or include audio, voice, noise, or the like that may be sensed within the environment of the acoustic sensor 419.

[0247] In some demonstrative aspects, the first filter 452 may be configured to generate a first filtered signal 463 that includes a first estimate of the AFB 460, e.g., between the acoustic transducer 408 and the acoustic sensor 419, e.g., as described below.

[0248] In some demonstrative aspects, the second filter 454 may be configured to generate a second filtered signal 481 that includes a second estimate of the AFB 460, e.g., between the acoustic transducer 408 and the acoustic sensor 419, e.g., as described below.

[0249] In some demonstrative aspects, the second filter 454 may be configured to generate a second filtered signal 481 based on a change in the AFB 460, e.g., between the acoustic transducer 408 and the acoustic sensor 419, e.g., as described below.

[0250] In some demonstrative aspects, the first filter 452 may include an adaptive filter that may be adapted based on a predefined (virtual) signal 499, for example, as described below.

[0251] In some demonstrative aspects, the predefined signal 499 may include a virtual signal that may be generated internally, for example, by the AFB mitigator 450 and / or by any other element of a system, e.g., an AAC system, that utilizes the AFB mitigator 450.

[0252] In some demonstrative aspects, the predefined signal 499 may include a virtual noise signal.

[0253] In some demonstrative aspects, the predefined signal 499 may include a virtual white noise signal.

[0254] In some demonstrative aspects, the predefined signal 499 may include a virtual pink noise signal.

[0255] In some demonstrative aspects, the frequency spectrum of the predefined signal 499 may be different from the frequency spectrum of the first input signal 461 .

[0256] In other aspects, the predefined signal 499 may include any other type of predefined signal.

[0257] In some demonstrative aspects, the first filter 452 may be adapted, for example, based on a subtraction of the filtered pre-defined signal 497 from a difference between the AFB mitigated signal 483 and the second filtered signal 481. For example, as shown in FIG. 4, the filtered pre-defined signal 497 may include a pre-defined signal 499 filtered by the first filter 452.

[0258] In some demonstrative aspects, the AFB mitigator 450 may include an adder 491 to generate a modified sensor signal 480, for example, by adding a filtered predefined signal 497 to the second input signal 469.

[0259] In some demonstrative aspects, the AFB mitigator 450 may include a first subtractor 492 to generate a first AFB mitigated signal 483, for example, by subtracting the first filtered signal 463 from the modified sensor signal 480. For example, as shown in FIG. 4, the second filter 454 may be adapted based on a difference between the first AFB mitigated signal 483 and the second filtered signal 481.

[0260] In some demonstrative aspects, the AFB mitigator 450 may include a second subtractor 494 to generate the second AFB mitigated signal 473, for example, by subtracting the filtered pre-defined signal 497 from the first AFB mitigated signal 483.

[0261] In some demonstrative aspects, the PF input 475 may be based on the second AFB mitigated signal 473.

[0262] In some demonstrative embodiments, the reference signal picked up by acoustic sensor 419 (the “microphone data signal”), denoted as rmic1, may be determined by Equations 2 and 3:

[0263] In some illustrative embodiments,

number

[0264] In some demonstrative embodiments, the modified sensor signal 480, denoted as rmic1′[n], may be, for example,

number

number

number

number

number

[0265] In some demonstrative aspects, an adaptive filter 454, denoted as H, may be configured to mitigate disturbances from the desired response of the acoustic feedback.

[0266] In some demonstrative aspects, a response, e.g., a desired response, to an adaptation H may be determined, for example, as follows:

number

number

number

number

number

number

[0267] In some exemplary embodiments, e H The residual error signal, denoted [n], may be determined, for example, as follows:

number

[0268] For example, signal 481 may be determined as follows:

number

[0269] In some demonstrative aspects, the coefficients of the filter H may be updated using an LMS algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant, e.g., as described below. In other aspects, any other suitable algorithm may be used.

[0270] In some demonstrative aspects, the coefficients of the filter H may be updated using an LMS algorithm, for example, as follows:

number

[0271] In some demonstrative aspects, an adaptive filter

number

number

[0272] In some demonstrative aspects, as shown in FIG. 4, an error signal of an adaptive filter H, e.g., a difference between signal 483 and signal 481, is

number

[0273] For example, the adaptive filter

number

number

number

[0274] In another aspect, an adaptive filter

number

[0275] In some demonstrative aspects, an adaptive filter

number

number

number

[0276] In some demonstrative aspects, signal 473, denoted as x, at a PF input 475 of PF 476 may be determined, for example, as follows:

number

[0277] In some demonstrative aspects, when the adaptive filter H converges, e.g.,

number

[0278] As a result, the adaptive filter

number

[0279] In some demonstrative aspects, an adaptive filter

number

number

number

number

[0280] Referring back to FIG. 1, in some demonstrative aspects, the AFB mitigator 150 may be configured to implement a first filter 152 that includes a fixed filter while using an internally generated virtual signal to adapt another filter (not shown in FIG. 1) of the AFB mitigator 150, e.g., as described below.

[0281] In some demonstrative aspects, AFB mitigator 150 may be configured to implement, for example, two adaptive filters in addition to fixed filter 152. For example, two adaptive filters, including, for example, adaptive filter 154 and another adaptive filter (not shown in FIG. 1 ), may be utilized to adapt to changes in the acoustic feedback path, for example, due to changes in the configuration of AAC system 100 and / or the environment of AAC system 100.

[0282] Reference is made to Fig. 5, which illustrates a schematic of an adaptive AFB mitigator 550 implemented within an AAC system in accordance with some demonstrative aspects. For example, AFB mitigator 150 (Fig. 1) may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 550.

[0283] In some demonstrative aspects, AFB mitigator 550 may be configured to mitigate acoustic feedback 560 between acoustic transducer 508 and acoustic sensor 519, such as a reference noise sensor and / or an error noise sensor in an AAC system, e.g., as described below. In one example, acoustic transducer 508 may include acoustic transducer 108 (FIG. 1), and / or acoustic sensor 519 may include reference noise sensor 119 (FIG. 1) or residual noise sensor 121 (FIG. 1).

[0284] In other aspects, one or more, e.g., some or all, of AFB mitigator 550 may be implemented by and / or configured to mitigate acoustic feedback for any other device and / or system, e.g., as described below.

[0285] In some demonstrative aspects, the AFB mitigator 550 may include a first filter 552 configured to generate a first filtered signal 563 by filtering a first input signal 561, e.g., according to and / or based on a first filter function, e.g., as described below.

[0286] In some demonstrative aspects, the first input signal 561 may be based on a transducer acoustic pattern output by the acoustic transducer 508, for example, as described below.

[0287] In some demonstrative aspects, the first input signal 561 may be based on a sound control pattern output by the acoustic transducer 508, for example, as described below.

[0288] In other aspects, the first input signal 561 may be based on any other type of transducer acoustic pattern output by the transducer 508. In one example, the first input signal 561 may be based on or include an audio signal output by the transducer 508.

[0289] In some demonstrative aspects, the AAC system may include a PF 576 that may be configured to generate a PF output 577 based on a PF input 575 .

[0290] In some demonstrative aspects, the PF 576 may be configured to generate the PF output 577 based on, for example, the PF input 575 and the acoustic configuration between the acoustic transducer 508 and an acoustic control zone of the AAC system, such as acoustic control zone 110 (FIG. 2). In other aspects, the PF 576 may be configured to generate the PF output 577 based on any other additional or alternative parameters and / or criteria.

[0291] In some demonstrative aspects, the sound control pattern output by the acoustic transducer 508 may be based on the PF output 577.

[0292] In some demonstrative aspects, the first input signal 561 may be based on the PF output 577.

[0293] In some demonstrative aspects, as shown in FIG. 5, the first input signal 561 may be based on the PF output 577 and one or more audio and / or voice signals 591, for example, as described below.

[0294] For example, the AAC system may include a combiner 593 for combining a signal based on the PF output 577 with one or more audio and / or speech signals 591, eg, a summation unit for summing.

[0295] For example, the one or more audio and / or voice signals 591 may include audio and / or voice signals heard within the sound control zone 110 (FIG. 2).

[0296] In other aspects, the first input signal 561 may be based on the PF output 577, for example, while one or more audio and / or voice signals 591 may be excluded.

[0297] In some demonstrative aspects, the AFB mitigator 550 may include a second filter 554 configured to generate a second filtered signal 581, e.g., by filtering the first input signal 561, e.g., according to and / or based on a second filter function, e.g., as described below.

[0298] In some demonstrative aspects, the second filter 554 may include an adaptive filter, for example, as described below.

[0299] In some demonstrative aspects, the second filter 554 may be adapted based on, for example, a difference between the AFB mitigated signal 583 and the second filtered signal 581, e.g., as described below.

[0300] In some demonstrative aspects, the AFB mitigated signal 583 may be based on the difference between the second input signal 569 and the first filtered signal 563, for example, as described below.

[0301] In some demonstrative aspects, the second input signal 569 may be based on a sensor acoustic pattern sensed by the acoustic sensor 519, for example, as described below.

[0302] In some demonstrative aspects, the second input signal 569 may be based on acoustic noise detected by the acoustic sensor 519, for example, as described below.

[0303] In other embodiments, the second input signal 569 may be based on any other type of transducer acoustic pattern sensed by the acoustic sensor 519. In one example, the second input signal 569 may be based on or include audio, voice, noise, or the like that may be sensed within the environment of the acoustic sensor 519.

[0304] In some demonstrative aspects, the first filter 552 may be configured to generate a first filtered signal 563 that includes a first estimate of the AFB 560, e.g., between the acoustic transducer 508 and the acoustic sensor 519, e.g., as described below.

[0305] In some demonstrative aspects, the second filter 554 may be configured to generate a second filtered signal 581 that includes a second estimate of the AFB 560, e.g., between the acoustic transducer 508 and the acoustic sensor 519, e.g., as described below.

[0306] In some demonstrative aspects, the second filter 554 may be configured to generate a second filtered signal 581 based on a change in the AFB 560, e.g., between the acoustic transducer 508 and the acoustic sensor 519, e.g., as described below.

[0307] In some demonstrative aspects, the first filter 552 may include a fixed filter having a fixed filter function, for example, as described below.

[0308] In some demonstrative aspects, the first filter 552 may include a fixed IIR filter, for example, as described below.

[0309] In other aspects, the first filter 552 may include a fixed FIR filter, or any other type of fixed filter.

[0310] In some demonstrative aspects, the fixed filter function of filter 552 may be based on a predefined acoustic configuration between acoustic transducer 508 and acoustic sensor 519, for example.

[0311] In some demonstrative aspects, the second filter 554 may be implemented by a short adaptive FIR filter, for example, as described below.

[0312] In other aspects, the second filter 554 may include any other adaptive FIR filter, an adaptive IIR filter, and / or any other adaptive filter.

[0313] In some demonstrative aspects, for example, as described below, the AFB mitigator 550 may include a third filter 556 configured to generate a third filtered signal 557, for example, by filtering the first input signal 561, for example, according to and / or based on a third filter function.

[0314] In some demonstrative aspects, the third filter 556 may include an adaptive filter, for example, as described below.

[0315] In some demonstrative aspects, the third filter 556 may be adapted based on a predefined (virtual) signal 599, for example, as described below.

[0316] In some demonstrative aspects, the predefined signal 599 may include a virtual signal that may be generated internally, for example, by the AFB mitigator 550 and / or by any other elements of a system, e.g., an AAC system, that utilizes the AFB mitigator 550.

[0317] In some demonstrative aspects, the predefined signal 599 may include a virtual noise signal.

[0318] In some demonstrative aspects, the predefined signal 599 may include a virtual white noise signal.

[0319] In some demonstrative aspects, the predefined signal 599 may include a virtual pink noise signal.

[0320] In some demonstrative aspects, the frequency spectrum of the predefined signal 599 may differ from the frequency spectrum of the first input signal 561.

[0321] In other aspects, the predefined signal 599 may include any other type of predefined signal.

[0322] In some demonstrative aspects, the third filter 556 may be adapted, for example, based on a subtraction of a filtered pre-defined signal 597 from a difference between the AFB mitigated signal 583 and the second filtered signal 581, as described below. For example, as shown in FIG. 5, the filtered pre-defined signal 597 may include a pre-defined signal 599 filtered by the third filter 556.

[0323] In some demonstrative aspects, as shown in FIG. 5, the AFB mitigator 550 may be configured according to a multi-filter AFB mitigation architecture utilizing a fixed pre-defined filter, e.g., filter 552, a speaker(s) / signal-based adaptation block, e.g., filter 554, and a virtual internally generated signal-based adaptation block, e.g., filter 556.

[0324] For example, a second filter 554, designated G, may be utilized to remove disturbances from the desired response of the acoustic feedback, and / or a third filter, designated H, may be utilized to accommodate changes in the AFB.

[0325] In some demonstrative aspects, filter H may use an input from a virtual internally generated signal 599, for example, to adapt the coefficients of filter H. The adapted coefficients of filter H may be applied to an input 561, for example, representing a speaker signal, to estimate a signal 557, denoted as Yh, that is reduced from a microphone path, e.g., an ANC microphone(s) path.

[0326] In some demonstrative aspects, the AFB mitigator 550 may include an adder 591 to generate a modified sensor signal 580, for example, by adding a filtered predefined signal 597 to the second input signal 569.

[0327] In some demonstrative aspects, the AFB mitigator 550 may include a first subtractor 592 to generate a first AFB mitigated signal, e.g., signal 583, e.g., by subtracting the first filtered signal 563 from the modified sensor signal 580.

[0328] In some demonstrative aspects, the AFB mitigator may include a second subtractor 594 to generate a second AFB mitigated signal 573, for example, by subtracting the sum of the filtered signals from the first AFB mitigated signal 583. For example, as shown in FIG. 5, the sum of the filtered signals may include a sum of the third filtered signal 557 and the filtered pre-defined signal 597.

[0329] In some demonstrative aspects, the PF input 575 may be based on the second AFB mitigated signal 573.

[0330] In some demonstrative embodiments, the reference signal picked up by acoustic sensor 519, denoted as rmic1 (the "microphone data signal"), may be determined by equations 2 and 3, using y to indicate the output by acoustic transducer 518, for example, including a combination of a sound control pattern (the "anti-noise signal" or "canceling signal") together with a voice / audio signal 591.

[0331] In some demonstrative aspects, signal 580, denoted as rmic1′[n], may be, for example, a signal v h [n] to the signal rmic1[n], where v h [n]=H[n] T v Lh [n], and H[n]=[H0[n],H1[n],..,H Lh [n] T denotes the impulse response of the filter H[n], and L h denotes the length of the filter H, and v Lh [n]=[v[n-1],v[n-2],..,v[nL h ]] T , L f 5 shows a sample predefined signal, e.g., a white noise signal vector (signal 599). For example, a signal v Lh [n] may be used as the input signal vector for the filter H in the adaptation process.

[0332] In some demonstrative aspects, a response, e.g., a desired response, for an adaptive filter G may be determined, for example, as follows:

number

number

number

number

number

number

[0333] In some exemplary embodiments, e g The residual error signal, denoted [n], may be determined, for example, as follows:

number

[0334] In some demonstrative aspects, the coefficients of the filter G may be updated, for example, according to an LMS algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant, e.g., as described below. In other aspects, any other suitable algorithm may be used.

[0335] In some demonstrative aspects, the coefficients of filter G may be updated according to the LMS algorithm, for example, as follows:

number

[0336] In some demonstrative aspects, the adaptive filter H may be excited by a predefined signal v[n], for example, random (white) noise.

[0337] In some demonstrative aspects, the error signal of filter G may be used as the desired response for adaptive filter H.

[0338] In some demonstrative aspects, the coefficients of the filter H may be updated, for example, according to an LMS algorithm and / or an LMS algorithm variant, such as NLMS, leaky LMS, and / or any other LMS variant. In other aspects, any other suitable algorithm may be used.

[0339] In some demonstrative aspects, the coefficients of the filter H may be updated according to the LMS algorithm, for example, as follows:

number

[0340] In some demonstrative aspects, after updating the coefficients of adaptive filter H, the updated coefficients of adaptive filter H may be copied to fixed filter H, e.g., taking y[n] as its input.

[0341] In some demonstrative aspects, a signal 573, denoted as x, at a PF input 575 of PF 576 may be determined, for example, as follows:

number

[0342] In some demonstrative aspects, when the adaptive filter G converges, e.g.,

number

[0343] As a result, the adaptive filter H may receive the desired response substantially free of disturbances.

[0344] In some demonstrative aspects, when the adaptive filter H converges, it ideally results in, for example,

number

number

[0345] 6, which illustrates a schematic of a controller 600 implementing AFB mitigation in accordance with some demonstrative aspects. In some aspects, the AAC controller 102 (FIG. 1) and / or the controller 193 (FIG. 1) may include one or more elements of the controller 600 and / or perform one or more functions and / or operations of the controller 600.

[0346] In some demonstrative aspects, the AAC controller 600 may be configured according to a non-hybrid scheme, for example, as described below.

[0347] In some demonstrative aspects, the non-hybrid scheme may include a noise prediction filter that may be applied to a prediction filter input that is based on a noise input, e.g., noise input 104 (FIG. 1), e.g., as described below.

[0348] In some demonstrative aspects, the controller 600 may receive multiple inputs 604, including, for example, input 104 (FIG. 1), from a noise sensor 602 representing acoustic noise at multiple predefined noise detection locations, for example, location 105 (FIG. 2).

[0349] In some demonstrative aspects, the controller 600 may generate a sound control signal 612 to control at least one acoustic transducer 614, such as acoustic transducer 108 (FIG. 1).

[0350] In some demonstrative aspects, the controller 600 may include an estimator ("prediction unit") 610 for estimating a signal 612 by applying an estimation function to an input 608 that corresponds to the input 604. For example, the estimator 610 may include a PF. For example, the PF 156 (FIG. 1) may include the estimator 610 and / or perform one or more functions of the estimator 610.

[0351] In some demonstrative aspects, the estimator 610 may include a PF implemented using a finite impulse response (FIR) filter.

[0352] In some demonstrative aspects, the estimator 610 may include a PF implemented using an infinite impulse response (IIR) filter. In one example, the estimator 610 may include a PF implemented using multiple cascaded second-order digital IIR filters in series.

[0353] In other aspects, other prediction filters may be used.

[0354] In some demonstrative aspects, the controller 600 may include an adaptive AFB mitigator 618 that may be configured to mitigate AFB between the acoustic transducer 614 and the reference noise acoustic sensor 602.

[0355] For example, AFB mitigator 150 (FIG. 1) may include and / or perform one or more functions of adaptive AFB mitigator 618.

[0356] In some demonstrative aspects, adaptive AFB mitigator 618 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 350 (FIG. 3).

[0357] In some demonstrative aspects, adaptive AFB mitigator 618 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 450 (FIG. 4).

[0358] In some demonstrative aspects, adaptive AFB mitigator 618 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 550 (FIG. 5).

[0359] 6, the controller 600 may include an extractor 606 to extract multiple independent reference acoustic patterns from the input 604. According to these embodiments, the input 608 may include multiple independent reference acoustic patterns.

[0360] In some demonstrative aspects, the controller 600 may generate a signal 612 configured to reduce and / or eliminate noise caused by one or more noise sources, for example, as described above.

[0361] In some demonstrative embodiments, the controller 600 may generate a sound control signal 612 configured to reduce and / or eliminate the noise energy and / or wave amplitude of one or more sound patterns within the sound control zone 110 (FIG. 2), while the noise energy and / or wave amplitude of one or more other sound patterns may be unaffected within the sound control zone 110 (FIG. 2).

[0362] In other embodiments, the controller 600 may not include the extractor 606. Accordingly, the input 608 may include the input 604 and / or any other input based on the input 604.

[0363] In some demonstrative aspects, the estimator 610 may apply any suitable linear and / or non-linear function to the input 608. For example, the estimation function may include a non-linear estimation function, such as a radial basis function.

[0364] In some demonstrative aspects, the estimator 610 may be capable of adapting one or more parameters of the estimation function based on a plurality of residual noise inputs 616 representing the acoustic residual noise at a plurality of predefined residual noise detection locations disposed within the noise control zone. For example, the inputs 616 may include inputs 106 (FIG. 1) representing the acoustic residual noise at a residual noise detection location 107 (FIG. 2), which may be located within the noise control zone 110 (FIG. 2).

[0365] In some demonstrative aspects, one or more of the inputs 616 may include at least one virtual microphone input corresponding to residual noise ("noise error") detected by at least one virtual error sensor at at least one particular residual noise sensor location of the positions 107 (FIG. 2). For example, the controller 600 may estimate the noise error at a particular residual noise sensor location based on the input 608 and the predicted noise signal 612, e.g., as described below.

[0366] In some demonstrative aspects, the estimator 610 may, for example, calculate y1(n)...y M The system may include a multiple-input multiple-output (MIMO) prediction unit configured to generate a plurality of sound control patterns, e.g., including M control patterns, denoted (n), corresponding to the nth sample, to drive a plurality of M respective acoustic transducers, e.g., based on the input 608.

[0367] Reference is now made to FIG. 7, which illustrates a schematic of a MIMO prediction unit 700 in accordance with some demonstrative aspects. In some demonstrative aspects, the estimator 610 (FIG. 6) may include the MIMO prediction unit 700 and / or perform one or more functions and / or operations of the MIMO prediction unit 700.

[0368] As shown in FIG. 7, a prediction unit 700 is a vector

number

[0369] In some demonstrative aspects, interference (crosstalk) between two or more of the M acoustic transducers of array 702 may occur, for example, when two or more, e.g., all, of the M acoustic transducers generate a controlled noise pattern, for example, simultaneously.

[0370] In some demonstrative aspects, the prediction unit 700 may generate an output 701 configured to control the array 702 to generate a substantially optimal sound control pattern, e.g., while simultaneously optimizing an input signal for each speaker in the array 702. For example, the prediction unit 700 may control multi-channel speakers of the array 702, e.g., while canceling interference between the speakers.

[0371] In one example, the prediction unit 700 may utilize a linear function with memory. For example, the prediction unit 700 may calculate y , which corresponds to the mth speaker of the array 702 for the nth sample of the sound control pattern, as follows: m The sound control patterns, denoted [n], may be determined:

number

[0372] In another example, the prediction unit 700 may implement any other suitable prediction algorithm, e.g., memory-based or memory-less, linear or non-linear, and the like, to determine the output 701.

[0373] In some demonstrative aspects, the prediction unit 700 generates the prediction filter coefficients W km[i] may be optimized, for example, based on multiple residual noise inputs 704, including multiple residual noise inputs 616 (FIG. 6). For example, the prediction unit 700 may optimize the prediction filter coefficients W km [n] may be optimized, for example, to reach maximum destructive interference at the residual error detection location 107 (FIG. 2). For example, the location 107 (FIG. 2) may include L locations, and the input 704 may include e1[n], e2[n],..., e L It may contain L residual noise components, denoted as [n].

[0374] In some demonstrative aspects, the prediction unit 700 generates the prediction filter coefficients W km One or more, e.g., some or all, of [i] may be optimized based on, e.g., a minimum mean square error (MMSE) criterion, or any other suitable criterion. For example, the prediction filter coefficients W km A cost function, denoted as J, for optimizing one or more, e.g., some or all, of the residual noise components e1[n], e2[n], ..., e[i] at positions 107 (FIG. 2) may be L The total energy of [n] can be defined, for example, as:

number

[0375] In some demonstrative aspects, at the lth position, the residual noise pattern, denoted as e1[n], may be expressed, for example, as follows:

number

[0376] In some demonstrative aspects, the prediction unit 700 calculates an adaptive weight vector W km One or more elements of [n], e.g., some or all of the elements, may be optimized to reach an optimal point, e.g., maximum noise reduction. For example, the prediction unit 700 may optimize the weight vector W at each step. km If [n] is updated in the negative direction of the gradient of the cost function J, then one may implement a gradient-based adaptation method, for example, as follows:

number

[0377] In other aspects, prediction unit 700 may be implemented according to any other prediction scheme and / or utilizing any other additional or alternative prediction algorithms.

[0378] Reference is now made to FIG. 8, which illustrates generally a controller 800 implementing AFB mitigation in accordance with some demonstrative aspects. For example, controller 193 (FIG. 1) may include one or more elements of controller 800 and / or perform one or more operations and / or functions of controller 800.

[0379] In some demonstrative aspects, the controller 800 may be configured according to a hybrid scheme, for example, as described below.

[0380] In some demonstrative aspects, the hybrid scheme may be configured to apply at least one noise prediction filter and at least one residual noise prediction filter, eg, as described below.

[0381] In some demonstrative aspects, a noise prediction filter may be configured to be applied to a prediction filter input, which may be based on a noise input, for example, as described below.

[0382] In some demonstrative aspects, a residual noise prediction filter may be configured to be applied to a prediction filter input, which may be based on a residual noise input, for example, as described below.

[0383] In some demonstrative aspects, as shown in FIG. 8, controller 800 may include a prediction filter 810 and a prediction filter 820, for example, as described below.

[0384] In some demonstrative aspects, as shown in FIG. 8, the controller 800 may generate a sound control signal 829 including, for example, a predicted noise signal based on, for example, the output of the prediction unit 810 and the output of the prediction unit 820.

[0385] In some demonstrative aspects, the controller 800 may output a sound control signal 829 to at least one acoustic transducer 808.

[0386] In some demonstrative aspects, prediction filter 810 and / or prediction filter 820 may be implemented by an FIR filter.

[0387] In other aspects, the predictive filter 810 and / or the predictive filter 820 may be implemented by an IIR filter. In one example, the predictive filter 810 and / or the predictive filter 820 may be implemented by multiple cascaded second-order digital IIR biquad filters in series.

[0388] In other aspects, other prediction filters may be used.

[0389] 8, the predictive filter 810 may include a noise predictive filter applied to a predictive filter input 812, which may be based on a noise input 816, for example, from one or more noise sensors 818 ("reference microphones"). For example, the predictive filter input 812 may be based on the noise input 104 (FIG. 1).

[0390] In some demonstrative aspects, the predictive filter 820 may include a residual noise predictive filter applied to a predictive filter input 822, which may be based on a residual noise input 826, for example, from one or more residual noise sensors 828 ("error microphones"). For example, the predictive filter input 822 may be based on the residual noise input 106 (FIG. 1).

[0391] In some demonstrative aspects, the input 826 may include at least one virtual microphone input corresponding to residual noise ("noise error") detected by at least one virtual error sensor at the virtual sensing location. For example, the controller 800 may estimate the noise error at the virtual sensing location based on the input 826 and the sound control signal 829, e.g., as described above.

[0392] In some demonstrative aspects, the controller 800 may generate a sound control signal 829 that may be configured to reduce and / or eliminate the noise energy and / or wave amplitude of one or more sound patterns within the sound control zone, for example, as described below, while the noise energy and / or wave amplitude of one or more other sound patterns may be unaffected within the sound control zone.

[0393] 8, the controller 800 may include an extractor 814 for extracting multiple independent reference acoustic patterns from an input 816. According to these aspects, the predictive filter input 812 may include multiple independent reference acoustic patterns.

[0394] In other aspects, the extractor 814 may be omitted and the predictive filter input 812 may be generated directly or indirectly based on the input 816, for example, according to any other algorithm and / or calculation.

[0395] 8, the controller 800 may include an extractor 824 for extracting multiple independent residual noise acoustic patterns from an input 826. According to these aspects, the predictive filter input 822 may include multiple independent residual noise acoustic patterns.

[0396] In other aspects, the extractor 824 may be omitted and the predictive filter input 822 may be generated directly or indirectly based on the input 826, for example, according to any other algorithm and / or calculation.

[0397] In some demonstrative aspects, as shown in FIG. 8, the controller 800 may include an AFB mitigator (“echo canceller”) 815 configured to partially or completely reduce, remove, and / or cancel a portion of the signal generated by the speaker 808 from the output signal of the reference microphone 818.

[0398] For example, AFB mitigator 150 (FIG. 1) may include AFB mitigator 815 and / or perform one or more functions of AFB mitigator 815.

[0399] In some demonstrative aspects, AFB mitigator 815 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 350 (FIG. 3).

[0400] In some demonstrative aspects, AFB mitigator 815 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 450 (FIG. 4).

[0401] In some demonstrative aspects, AFB mitigator 815 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 550 (FIG. 5).

[0402] In some demonstrative aspects, as shown in FIG. 8, the controller 800 may include an AFB mitigator (“echo canceller”) 825 configured to partially or completely reduce, remove, and / or cancel a portion of the signal generated by the speaker 808 from the output signal of the residual noise microphone 828.

[0403] For example, AFB mitigator 150 (FIG. 1) may include AFB mitigator 825 and / or perform one or more functions of AFB mitigator 825.

[0404] In some demonstrative aspects, AFB mitigator 825 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 350 (FIG. 3).

[0405] In some demonstrative aspects, AFB mitigator 825 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 450 (FIG. 4).

[0406] In some demonstrative aspects, AFB mitigator 825 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 550 (FIG. 5).

[0407] In some demonstrative aspects, controller 800 may apply any suitable linear and / or nonlinear function to prediction filter input 812 and / or prediction filter input 822. For example, prediction filter 820 and / or prediction filter 820 may be configured according to a linear estimation function, or a nonlinear estimation function, such as a radial basis function.

[0408] In some demonstrative aspects, the controller 800 may be configured according to an adaptive hybrid scheme. For example, as shown in FIG. 8, the controller 800 may be configured to update one or more parameters of the predictive filter 810 and / or the predictive filter 820 based on, for example, the residual noise input 826.

[0409] Reference is made to FIG. 9, which illustrates a schematic of a vehicle 900 including an AAC system, in accordance with some demonstrative aspects.

[0410] In one example, vehicle 940 may include only or more elements and / or components of AAC system 100 (FIG. 1), for example, to control sound within one or more sound control zones within vehicle 900.

[0411] In some demonstrative aspects, as shown in FIG. 9, a vehicle 900 may include multiple speakers 908, multiple residual noise sensors (“monitoring microphones”) 912, and multiple reference sensors (“environmental microphones”).

[0412] In some demonstrative aspects, the vehicle 900 may include an AAC controller 102 ( FIG. 1 ) configured to control a plurality of speakers 908 to provide a first sound control zone 930 to a driver of the vehicle 900, for example, at the driver's headrest position.

[0413] In some demonstrative aspects, the AAC controller 102 (FIG. 1) can be configured to control multiple speakers 908 to provide a second sound control zone 926, e.g., to a passenger, e.g., in the front seat near the driver's seat, e.g., at the passenger headrest position.

[0414] In some demonstrative embodiments, as shown in FIG. 9, multiple monitoring microphones 912 may be positioned within first and second sound control zones 930 and 926.

[0415] In some demonstrative embodiments, as shown in FIG. 9, multiple environmental microphones 910 can be positioned in the environment outside of the sound control zones 930 and 926.

[0416] In other aspects, the vehicle 900 may include any other number of speakers 908, monitoring microphones 912, and / or environmental microphones 910, any other arrangements, positions, and / or locations of the speakers 908, monitoring microphones 912, and / or environmental microphones 910, and / or any other additional or alternative components.

[0417] 10, which illustrates a schematic of an AFB mitigator 1000, in accordance with some demonstrative aspects. For example, AFB mitigator 150 (FIG. 1) may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 1000.

[0418] In some demonstrative aspects, the AFB mitigator 1000 may be configured to mitigate acoustic feedback between at least one acoustic transducer 1008, e.g., one acoustic transducer 1008 or multiple acoustic transducers 1008, and at least one acoustic sensor 1019, e.g., one acoustic sensor 1019 or multiple acoustic sensors 1019, for example, as described below.

[0419] In some demonstrative aspects, the AFB mitigator 1000 may be configured to provide an output including an AFB mitigated signal, e.g., AFB mitigated signal 1073, which may be based on AFB mitigation applied to a sensor acoustic pattern 1080 detected by the acoustic sensor 1019, for example, as described below.

[0420] In some demonstrative aspects, the AFB mitigated signal 1073 may be based on a sensor acoustic pattern 1080 sensed by the acoustic sensor 1019, e.g., post-AFB mitigation to mitigate acoustic feedback between the acoustic transducer 1008 and the acoustic sensor 1019, e.g., as described below.

[0421] In some demonstrative aspects, the AFB mitigator 1000 may include a first filter (F1) 1052 that may be configured to generate a first filtered signal 1063, e.g., by filtering a first input signal 1061, e.g., according to and / or based on a first filter function, e.g., as described below.

[0422] In some demonstrative aspects, the first input signal 1061 may be based on a transducer acoustic pattern output by the transducer 1008, for example, as described below.

[0423] In some demonstrative aspects, the AFB mitigator 1000 may include a second filter (F2) 1054 that may be configured to generate a second filtered signal 1081, for example, by filtering the first input signal 1061, for example, according to and / or based on a second filter function, for example, as described below.

[0424] In some demonstrative aspects, the second filter 1054 may include an adaptive filter, for example, as described below.

[0425] In some demonstrative aspects, the second filter 1054 may be adapted based on, for example, a difference between the AFB mitigated signal 1083 and the second filtered signal 1081, e.g., as described below.

[0426] In some demonstrative aspects, the AFB mitigated signal 1083 may be based on the difference between the second input signal 1069 and the first filtered signal 1063, for example, as described below.

[0427] In some demonstrative aspects, the second input signal 1069 may be based on a sensor acoustic pattern 1080 sensed by the acoustic sensor 1019, for example, as described below.

[0428] In some demonstrative aspects, the second input signal 1069 may be based directly on, e.g., may include, or may be equal to, the sensor acoustic pattern 1080 sensed by the acoustic sensor 1019, e.g., as described above.

[0429] In some demonstrative aspects, the second input signal 1069 may be indirectly based on the sensor acoustic pattern 1080 sensed by the acoustic sensor 1019. For example, the second input signal 1069 may include a processed signal, which may be based on processing of the sensor acoustic pattern 1080 sensed by the acoustic sensor 1019, for example, as described above.

[0430] In some demonstrative aspects, the second input signal 1069 may be based on audio, voice, noise, or the like that may be sensed within the environment of the acoustic sensor 1019.

[0431] In some demonstrative aspects, the first filter 1052 may be configured to generate a first filtered signal 1063 that includes a first estimate of the AFB between the acoustic transducer 1008 and the acoustic sensor 1019, for example, as described above.

[0432] In some demonstrative aspects, the second filter 1054 may be configured to generate a second filtered signal 1081 that includes a second estimate of the AFB between the acoustic transducer 1008 and the acoustic sensor 1019, for example, as described above.

[0433] In some demonstrative aspects, the second filter 1054 may be configured to generate a second filtered signal 1081 based on, for example, a change in the AFB between the acoustic transducer 1008 and the acoustic sensor 1019, for example, as described above.

[0434] In some demonstrative aspects, the first filter 1052 may include a fixed filter having a fixed filter function, for example, as described above.

[0435] In some demonstrative aspects, the first filter 1052 may include a fixed IIR filter, for example, as described above.

[0436] In other aspects, the first filter 1052 may include a fixed FIR filter, or any other type of fixed filter.

[0437] In some demonstrative aspects, the fixed filter function of the filter 1052 may be based on a predefined acoustic configuration between the acoustic transducer 1008 and the acoustic sensor 1019, for example.

[0438] In some demonstrative aspects, the AFB mitigator 1000 may include a first subtractor 1091 for generating a first AFB mitigated signal 1083, for example, by subtracting the first filtered signal 1063 from the second input signal 1069.

[0439] In some demonstrative aspects, the AFB mitigator 1000 may include a second subtractor 1092 to generate a second AFB mitigated signal, e.g., the AFB mitigated signal 1073, e.g., by subtracting the signal 1089 from the first AFB mitigated signal 1083.

[0440] In some demonstrative aspects, the signal 1089 may be based on the second filtered signal 1081 .

[0441] In some demonstrative aspects, the signal 1089 may be based directly on, e.g., may include, or may be equal to, the second filtered signal 1081, e.g., as described above with respect to FIG. 3.

[0442] In some demonstrative aspects, signal 1089 may be indirectly based on second filtered signal 1081. For example, signal 1089 may be generated by another filter (not shown in FIG. 10), which may be adapted based on second filtered signal 1081, e.g., as described above with respect to FIGS. 4 and / or 5.

[0443] In some demonstrative aspects, the second filter 1054 may be adapted based on a difference between the first AFB mitigated signal 1083 and the second filtered signal 1081.

[0444] In some demonstrative aspects, the second filter 1054 may be implemented by a short adaptive FIR filter, for example, as described above.

[0445] In other aspects, the second filter 1054 may include any other adaptive FIR filter, an adaptive IIR filter, and / or any other adaptive filter.

[0446] In some demonstrative aspects, the AFB mitigated signal 1073 may be processed, for example, according to one or more processing techniques 1088 to provide a signal 1075.

[0447] In some demonstrative aspects, the signal 1075 may be provided as an input to one or more elements of a system or device implementing at least one acoustic transducer 1008 and at least one acoustic sensor 1019, for example, as described below.

[0448] In some demonstrative aspects, the signal 1075 may be provided as an output signal, for example an output audio signal, provided to a user of a device implementing the acoustic sensor 1019 and the acoustic transducer 1008.

[0449] In some demonstrative aspects, signal 1061 may be based on signal 1075, for example, as described below.

[0450] In some demonstrative aspects, signal 1061 may be indirectly based on, e.g., may include, or may be equal to, signal 1075, e.g., as described above with respect to Figures 3, 4, and / or 5.

[0451] In some demonstrative aspects, signal 1061 may be indirectly based on signal 1075. For example, signal 1061 may be generated based on, for example, further processing of signal 1075, with or without one or more other signals, for example, as described above with respect to Figures 3, 4, and / or 5.

[0452] In some demonstrative aspects, the processing technique 1088 may be configured to generate a signal 1075 configured for AAC processing, for example, as described above.

[0453] In some demonstrative aspects, the processing technique 1088 may be configured to generate the signal 1075 by applying a PF to the AFB mitigated signal 1073, for example, as described above with respect to Figures 3, 4, and / or 5.

[0454] In some demonstrative embodiments, the at least one acoustic sensor 1019 may include at least one reference noise sensor, such as reference noise sensor 119 (FIG. 1).

[0455] For example, the second input signal 1069 may represent noise detected by a reference noise sensor, eg, reference noise sensor 119 (FIG. 1), at a noise detection location, eg, noise detection location 105 (FIG. 1).

[0456] For example, the processing technique 1088 may be configured to generate the signal 1075 by applying a PF to the AFB mitigated signal 1073, eg, as described above with respect to FIGS. 3, 4, and / or 5.

[0457] In one example, AFB mitigator 618 (FIG. 6) may be configured to implement one or more functions of AFB mitigator 1000 to generate input 604 (FIG. 6) and / or input 608 (FIG. 6), which may include or be based on AFB mitigated signal 1073, for example.

[0458] For example, the processing technique 1088 may be configured to perform one or more functions of the estimator 610 (FIG. 6) to generate a sound control signal 612 (FIG. 6), which may include or be based on, for example, the signal 1075.

[0459] In some demonstrative embodiments, the at least one acoustic sensor 1019 may include at least one residual noise sensor, such as residual noise sensor 121 (FIG. 1).

[0460] For example, the second input signal 1069 may represent noise detected by a residual noise sensor, eg, residual noise sensor 121 (FIG. 1), at a residual noise detection location, eg, residual noise detection location 107 (FIG. 1).

[0461] For example, the processing technique 1088 may be configured to generate a signal 1075 that represents the AFB mitigated residual noise signal 1033 .

[0462] For example, the AFB mitigated residual noise signal 1033 may be processed according to one or more residual noise processing techniques 1035.

[0463] For example, the controller 193 (FIG. 1) may be configured to implement a residual noise processing technique 1035 to process an AFB-mitigated residual noise signal 1033, which may be generated, for example, based on the residual noise input 106 (FIG. 1), as described above.

[0464] In one example, the residual noise processing technique 1035 may be implemented to adapt one or more parameters of an estimation function of the estimator 610 (FIG. 6), e.g., based on the AFB mitigated residual noise signal 1033, as described above.

[0465] In some demonstrative aspects, the processing technique 1088 may be configured to generate a signal 1075 to represent the acoustic pattern of a virtual acoustic sensor, which may be located at a location different from the location of the physical acoustic sensor 1019, e.g., as described below.

[0466] In one example, the processing technique 1088 may be configured to generate signal 1075, for example, by applying an acoustic transfer function to the AFB mitigated signal 1073, which may be based on an acoustic path between the location of the virtual acoustic sensor and the location of the physical acoustic sensor 1019.

[0467] In some demonstrative aspects, the processing technique 1088 may be configured to generate a signal 1075 to represent an AFB-mitigated residual noise signal 1033 of a virtual residual noise acoustic sensor, which may be positioned at a virtual residual noise acoustic sensing location, for example, as described below.

[0468] In some demonstrative aspects, the virtual residual noise acoustic sensing location may be different from the location of the physical acoustic sensor 1019, which may provide the second input signal 1069.

[0469] In some demonstrative aspects, the processing technique 1088 may be configured to generate a first signal (also referred to as a “physical sensor filtered signal”) based on the AFB mitigated signal 1073.

[0470] In some demonstrative aspects, the processing technique 1088 may be configured to generate a physical sensor filtered signal, for example, by applying an acoustic transfer function to the AFB mitigated signal 1073, which may be based on an acoustic path between the location of the physical acoustic sensor 1019 and the location of the virtual acoustic sensor.

[0471] In some demonstrative aspects, the processing technique 1088 may be configured to generate a second signal (also referred to as a “physical transducer filtered signal”) based on the signal 1061 provided to the at least one transducer 1008.

[0472] In some demonstrative aspects, the processing technique 1088 may be configured to generate a physical transducer filtered signal, for example, by applying an acoustic transfer function to the signal 1061, which may be based on an acoustic path between the position of the acoustic transducer 1008 and the position of a virtual acoustic sensor.

[0473] In some demonstrative aspects, the processing technique 1088 may be configured to generate a signal 1075, for example based on a summation of a physical-sensor filtered signal and a physical transducer filtered signal, to represent the AFB-mitigated residual noise signal 1033 of the virtual residual noise acoustic sensor.

[0474] In some demonstrative aspects, the residual noise processing technique 1035 may be implemented with respect to the AFB-mitigated residual noise signal 1033 of the virtual residual noise acoustic sensor.

[0475] For example, a residual noise processing technique 1035 may be implemented to adapt one or more parameters of an estimation function of the estimator 610 (FIG. 6), e.g., as described above, based on, e.g., the AFB-mitigated residual noise signal 1033 of a virtual residual noise acoustic sensor.

[0476] In some demonstrative aspects, signal 1061 may be provided independently or without association with signal 1075 and / or AFB mitigated signal 1073.

[0477] In some demonstrative aspects, the signal 1061 may be based on a first audio signal provided to a user of a device implementing the AFB mitigator 1000, and / or the sensor acoustic pattern 1080 may be based on a second audio signal processed by the processing technique 1088.

[0478] In some demonstrative aspects, the AFB mitigator 1000 may be implemented by a user device, such as a smartphone, tablet, laptop, or any other computing device, for example, as described below.

[0479] For example, the AFB mitigator 1000 may be configured to mitigate AFB between the acoustic transducer 1008 and the acoustic sensor 1019, e.g., in a use case in which a user of a computing device is simultaneously utilizing the acoustic transducer 1008 to provide an audio output while the acoustic sensor 1019 is operating to detect a sensor acoustic pattern 1080 in the computing device's environment, e.g., as described below.

[0480] In some demonstrative aspects, AFB mitigator 1000 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 350 (FIG. 3).

[0481] In some demonstrative aspects, the AFB mitigator 1000 may be configured to support technical solutions that utilize virtual signals in the adaptation process of the adaptive filter 1054, for example, as described above with respect to FIG.

[0482] In some demonstrative aspects, AFB mitigator 1000 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 450 (FIG. 4).

[0483] In some demonstrative aspects, the AFB mitigator 1000 may be configured to implement a first filter 1052 that includes a fixed filter while utilizing an internally generated virtual signal to adapt another filter (not shown in FIG. 1) of the AFB mitigator 1000, e.g., as described above with respect to FIG. 5.

[0484] In some demonstrative aspects, AFB mitigator 1000 may include one or more elements and / or perform one or more functions of adaptive AFB mitigator 550 (FIG. 5).

[0485] Reference is now made to FIG. 11, which illustrates a schematic of a computing device 1100 including an AFB mitigator 1150 in accordance with some demonstrative aspects.

[0486] In some demonstrative aspects, the computing device 1100 may include, for example, a user equipment (UE), a mobile device (MD), a smartphone, a mobile computer, a laptop computer, a notebook computer, a tablet computer, a desktop computer, a personal computer (PC), a handheld computer, a mobile terminal, a wearable device, a consumer device, a vehicular device, a non-vehicular device, a mobile or portable device, a non-mobile or non-portable device, a mobile phone, a cellular phone, a video device, an audio device, an audio / video (A / V) device, a video source, an audio source, a video sink, an audio sink, a stereo tuner, a broadcast radio receiver, a game console, a media player, a music player, or the like.

[0487] In some demonstrative aspects, computing device 1100 may include, for example, one or more of processor 1191, input device 1192, output device 1193, memory device 1194, and / or storage device 1195. Device 1100 may optionally include other suitable hardware and / or software components. In some demonstrative aspects, some or all of the components of computing device 1100 may be housed within a common housing or packaging and may be interconnected or operatively associated using one or more wired or wireless links. In other aspects, one or more components of computing device 1100 may be distributed among multiple or separate devices.

[0488] In some demonstrative aspects, the processor 1191 may include, for example, a central processing unit (CPU), a digital signal processor (DSP), one or more processor cores, a single-core processor, a dual-core processor, a multi-core processor, a microprocessor, a host processor, a controller, multiple processors or controllers, a chip, a microchip, one or more electrical circuits, circuits, logic units, integrated circuits (ICs), application specific ICs (ASICs), or any other suitable general-purpose or special-purpose processor or controller. The processor 1191 may execute instructions of, for example, an operating system (OS) of the computing device 1100 and / or one or more suitable applications.

[0489] In some demonstrative aspects, the input device 1192 may include, for example, one or more acoustic sensors 1119, such as audio microphones.

[0490] In some demonstrative aspects, the input device(s) 1192 may include, for example, a keyboard, a keypad, a mouse, a touch screen, a touchpad, a trackball, a stylus, and / or other suitable pointing or input device.

[0491] In some demonstrative aspects, the output device(s) 1193 may include, for example, one or more acoustic transducers 1108, such as audio speakers.

[0492] In some demonstrative aspects, output device(s) 1193 may include, for example, a monitor, a screen, a touch screen, a flat panel display, a light emitting diode (LED) display, a liquid crystal display (LCD) display, and / or other suitable output device.

[0493] In some demonstrative aspects, the memory device 1194 may include, for example, random access memory (RAM), read only memory (ROM), dynamic RAM (DRAM), synchronous DRAM (SD-RAM), flash memory, volatile memory, non-volatile memory, cache memory, buffer, short-term memory device, long-term memory device, or other suitable memory device. The storage device 1195 may include, for example, a hard disk drive, a disk drive, a solid-state drive (SSD), and / or other suitable removable or non-removable storage device. The memory device 1194 and / or the storage device 1195 may store, for example, data processed by the computing device 1100.

[0494] In some demonstrative aspects, the AFB mitigator 1150 may be implemented by the processor 1191, for example, as part of the OS of the computing device 1100, as part of an application executed by the computing device 1100, and / or as a dedicated AFB mitigation application executed by the computing device.

[0495] In some demonstrative aspects, AFB mitigator 1150 may include one or more elements and / or perform one or more functions of AFB mitigator 1000 (FIG. 10).

[0496] In some demonstrative aspects, the AFB mitigator 1150 may be configured to mitigate acoustic feedback 1160 between one or more acoustic transducers 1108 and one or more acoustic sensors 1119, for example, as described below.

[0497] In some demonstrative aspects, the AFB mitigator 1100 may be configured to mitigate AFB between one or more acoustic transducers 1108 and one or more acoustic sensors 1119, e.g., in a use case in which a user of the computing device 1100 is simultaneously utilizing the acoustic transducer 1108 to provide an audio output while the acoustic sensor 1119 is operating to detect sensor acoustic patterns within the computing device 1100's environment, e.g., as described below.

[0498] In some demonstrative aspects, the AFB mitigator 1100 may be configured to mitigate AFB between the acoustic transducer 1108 and the acoustic sensor 1119, e.g., during a speakerphone conversation between a user of the computing device 110 and another person. For example, the sensor acoustic pattern sensed by the acoustic sensor 1119 may include voice data of the user, and the acoustic pattern generated by the acoustic transducer 1108 may include voice data of the other person, e.g., as received via a communications link between the computing device 1100 and a communications network. For example, the computing device 1100 may be configured to process the user's voice data for transmission to the other person, e.g., via the communications network.

[0499] In one example, the AFB mitigator 1150 may be configured to provide a mitigator output 1173 that may be configured to reduce feedback effects for an “open speaker” mode of operation of the computing device 1110 .

[0500] For example, in “open speaker” mode, acoustic feedback 1160 may include feedback of played voice / audio from acoustic transducer 1108 back to acoustic sensor 1119 .

[0501] For example, the AFB mitigator 1150 may be configured to generate a mitigator output 1173 that is applied to a detected sensor acoustic pattern detected by the acoustic sensor 1119 .

[0502] For example, the mitigator output 1173 may be configured to provide a relatively clear "audio" for open speaker mode, including the voice of the user of the computing device 1110, to be transmitted back to the other side of the link.

[0503] Reference is now made to Fig. 12, which illustrates a method for adaptive AFB mitigation. For example, one or more of the operations of Fig. 12 may be performed by one or more components of AAC system 100 (Fig. 1), controller 102 (Fig. 1), controller 193 (Fig. 1), AFB mitigator 150 (Fig. 1), AFB mitigator 350 (Fig. 3), AFB mitigator 450 (Fig. 4), AFB mitigator 550 (Fig. 5), AFB mitigator 1000 (Fig. 10), AFB mitigator 1150 (Fig. 11), controller 600 (Fig. 6), and / or controller 800 (Fig. 8).

[0504] In some demonstrative aspects, the method of FIG. 12 may include a method for mitigating AFB between an acoustic transducer and an acoustic sensor, e.g., in an AAC system and / or any other system, e.g., as described below.

[0505] In some demonstrative aspects, as shown in block 1202, the method may include generating a first filtered signal by filtering the first input signal with a first filter, e.g., according to and / or based on a first filter function. For example, the first input signal may be based on a transducer acoustic pattern output by an acoustic transducer. For example, the AFB mitigator 1000 (FIG. 10) may be configured to generate a first filtered signal with the first filter 1052 (FIG. 10) by filtering the first input signal 1061 (FIG. 10), e.g., according to and / or based on a first filter function, e.g., as described above.

[0506] In some demonstrative aspects, as shown in block 1204, the method may include generating a second filtered signal by a second filter by filtering the first input signal, e.g., according to and / or based on a second filter function. For example, the second filter may include an adaptive filter that may be adapted, e.g., based on a difference between the AFB mitigated signal and the second filtered signal. For example, the AFB mitigated signal may be based on a difference between the second input signal and the first filtered signal. For example, the second input signal may be based on a sensor acoustic pattern sensed by an acoustic sensor. For example, the AFB mitigator 1000 (FIG. 10) may be configured to generate a second filtered signal 1081 (FIG. 10) by a second filter 1054 (FIG. 10), which may be adapted, e.g., based on a difference between the AFB mitigated signal 1083 (FIG. 10) and the second filtered signal 1081 (FIG. 10), as described above.

[0507] 13, which illustrates, in schematic form, a product 1300 in accordance with some demonstrative aspects. Product 1300 may include one or more tangible computer-readable ("machine-readable") non-transitory storage media 1302 that, when executed by at least one processor, e.g., a computer processor, controls AAC system 100 (FIG. 1), controller 102 (FIG. 1), controller 193 (FIG. 1), AFB mitigator 150 (FIG. 1), AFB mitigator 350 (FIG. 3), AFB mitigator 450 (FIG. 4), AFB mitigator 550 (FIG. 5), AFB mitigator 1000 (FIG. 10), AFB mitigator 1100 (FIG. 11), AFB mitigator 1200 (FIG. 12), AFB mitigator 1300 (FIG. 13), AFB mitigator 1400 (FIG. 14), AFB mitigator 150 (FIG. 15), AFB mitigator 350 (FIG. 3), AFB mitigator 450 (FIG. 4), AFB mitigator 550 (FIG. 5), AFB mitigator 1000 (FIG. 15), AFB mitigator 1600 (FIG. 16), AFB mitigator 1700 (FIG. 17), AFB mitigator 1800 (FIG. 18), AFB mitigator 1900 (FIG. 19), AFB mitigator 2000 (FIG. 20), AFB mitigator 2000 (FIG. 21), AFB mitigator 2000 (FIG. 22), AFB mitigator 2000 (FIG. 23), AFB mitigator 20 150 (FIG. 11), controller 600 (FIG. 6), and / or controller 800 (FIG. 8); execute one or more operations, and / or enable one or more operations, communications, and / or functions described above with reference to FIGS. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and / or 12, and / or one or more operations described herein. The phrases "non-transitory machine-readable medium(s)" and "computer-readable non-transitory storage medium(s)" are intended to include all computer-readable media, with the sole exception of transitory propagating signals.

[0508] In some demonstrative aspects, the product 1300 and / or the storage medium 1302 may include one or more types of computer-readable media capable of storing data, including volatile memory, non-volatile memory, removable or fixed memory, erasable or non-erasable memory, writable or rewriteable memory, and the like. For example, the storage medium 1302 may include RAM, DRAM, double data rate DRAM (DDR-DRAM), SDRAM, static RAM (SRAM), ROM, programmable ROM (PROM), erasable programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), flash memory, (e.g., NOR or NAND flash memory), content addressable memory (CAM), polymer memory, phase change memory, ferroelectric memory, silicon-oxide-nitride-oxide-silicon (SONOS) memory, disk, hard drive, and the like. The computer-readable storage medium may include any suitable medium involving the downloading or transmission of a computer program from a remote computer to a requesting computer, conveyed over a communications link, e.g., a modem, wireless or network connection, by a data signal embodied in a carrier wave or other propagation medium.

[0509] In some demonstrative aspects, the logic 1304 may include instructions, data, and / or code that, when executed by a machine, may cause the machine to perform the methods, processes, and / or operations described herein. The machine may include, for example, any suitable processing platform, computing platform, computing device, processing device, computing system, processing system, computer, processor, or the like, and may be implemented using any suitable combination of hardware, software, firmware, and the like.

[0510] In some demonstrative aspects, the logic 1304 may include or be implemented as software, software modules, applications, programs, subroutines, instructions, instruction sets, computing code, words, values, symbols, and the like. The instructions may include any suitable type of code, such as source code, compiled code, interpreted code, executable code, static code, dynamic code, and the like. The instructions may be implemented according to a predefined computer language, manner or syntax to instruct a processor to perform a function. The instructions may be implemented using any suitable high-level, low-level, object-oriented, visual, compiled and / or interpreted programming language.

[0511] example The following examples relate to further aspects.

[0512] Example 1 includes an apparatus including an acoustic feedback (AFB) mitigator configured to mitigate acoustic feedback (AFB) between an acoustic transducer and an acoustic sensor, the AFB mitigator including: a first filter configured to generate a first filtered signal by filtering a first input signal, the first input signal being based on a transducer acoustic pattern output by the acoustic transducer; and a second filter configured to generate a second filtered signal by filtering the first input signal, the second filter including an adaptive filter adapted based on a difference between the AFB mitigated signal and the second filtered signal, the AFB mitigated signal being based on a difference between the second input signal and the first filtered signal, the second input signal being based on a sensor acoustic pattern sensed by the acoustic sensor.

[0513] Example 2 includes the subject matter of example 1, and optionally, the first filter includes a fixed filter having a fixed filter function.

[0514] Example 3 includes the subject matter of example 2, and optionally, the fixed filter function is based on a predefined acoustic configuration of a system including an acoustic transducer and an acoustic sensor.

[0515] Example 4 includes the subject matter of example 2 or example 3, and optionally, the fixed filter function is based on a predefined acoustic configuration between the acoustic transducer and the acoustic sensor.

[0516] Example 5 includes the subject matter of any one of Examples 2-4, and optionally includes a first subtractor for generating a first AFB-mitigated signal by subtracting the first filtered signal from the second input signal, and a second subtractor for generating a second AFB-mitigated signal by subtracting the second filtered signal from the first AFB-mitigated signal, wherein the second filter is adapted based on a difference between the first AFB-mitigated signal and the second filtered signal.

[0517] Example 6 includes the subject matter of example 5, optionally wherein the first input signal is based on an output of a predictive filter, and the input to the predictive filter is based on a second AFB-mitigated signal.

[0518] Example 7 includes the subject matter of Example 2, and optionally includes a third filter configured to generate a third filtered signal by filtering the first input signal, the third filter including an adaptive filter that is adapted based on a subtraction of the filtered pre-defined signal from a difference between the AFB mitigated signal and the second filtered signal, and the filtered pre-defined signal includes the pre-defined signal filtered by the third filter.

[0519] Example 8 includes the subject matter of example 7, optionally wherein the predefined signal includes a noise signal.

[0520] Example 9 includes the subject matter of example 7 or example 8, optionally wherein a frequency spectrum of the predefined signal is different from a frequency spectrum of the first input signal.

[0521] Example 10 includes the subject matter of any one of Examples 7-9, and optionally includes an adder for generating a modified sensor signal by adding the filtered pre-defined signal to the second input signal, a first subtractor for generating a first AFB-mitigated signal by subtracting the first filtered signal from the modified sensor signal, and a second subtractor for generating a second AFB-mitigated signal by subtracting a sum of the filtered signals from the first AFB-mitigated signal, wherein the sum of the filtered signals includes a sum of the third filtered signal and the filtered pre-defined signal.

[0522] Example 11 includes the subject matter of example 10, and optionally, the first input signal is based on an output of a predictive filter, and the input to the predictive filter is based on a second AFB-mitigated signal.

[0523] Example 12 includes the subject matter of example 1, and optionally, the first filter includes an adaptive filter that is adapted based on subtraction of the filtered predefined signal from a difference between the AFB mitigated signal and the second filtered signal, and the filtered predefined signal includes the predefined signal filtered by the first filter.

[0524] Example 13 includes the subject matter of example 12, and optionally, the predefined signal includes a noise signal.

[0525] Example 14 includes the subject matter of example 12 or example 13, optionally wherein a frequency spectrum of the predefined signal is different from a frequency spectrum of the first input signal.

[0526] Example 15 includes the subject matter of any one of Examples 12-14, and optionally includes an adder for generating a modified sensor signal by adding the filtered predefined signal to the second input signal, a first subtractor for generating a first AFB-mitigated signal by subtracting the first filtered signal from the modified sensor signal, and a second subtractor for generating a second AFB-mitigated signal by subtracting the filtered signal from the first AFB-mitigated signal.

[0527] Example 16 includes the subject matter of example 15, and optionally, the first input signal is based on an output of a predictive filter, and the input to the predictive filter is based on a second AFB-mitigated signal.

[0528] Example 17 includes the subject matter of any one of Examples 1-16, and optionally, the first filter is configured to generate a first filtered signal including a first estimate of the AFB, and the second filter is configured to generate a second filtered signal including a second estimate of the AFB.

[0529] Example 18 includes the subject matter of any one of Examples 1-17, and optionally, the second filter is configured to generate a second filtered signal based on a change in the AFB.

[0530] Example 19 includes the subject matter of any one of Examples 1-18, and optionally includes a predictive filter (PF) configured to generate a PF output based on a PF input of an active acoustic control (AAC) system including an acoustic transducer and an acoustic sensor, where the first input signal is based on the PF output and the PF input is based on the AFB mitigated signal.

[0531] Example 20 includes the subject matter of example 19, optionally wherein the first input signal is based on a combination of the PF output and at least one of an audio signal or a voice signal.

[0532] Example 21 includes the subject matter of any one of Examples 1-20, and optionally, the first input signal is based on at least one of an audio signal or a speech signal.

[0533] Example 22 includes the subject matter of any one of Examples 1-21, and optionally, the second filter is adapted based on a least mean squares (LMS) algorithm or an LMS algorithm variant.

[0534] Example 23 includes the subject matter of any one of Examples 1-22, and optionally, at least one of the first filter or the second filter is a finite impulse response (FIR) filter.

[0535] Example 24 includes the subject matter of any one of Examples 1-23, and optionally, at least one of the first filter or the second filter is an infinite impulse response (IIR) filter.

[0536] Example 25 includes an article of manufacture including one or more tangible computer-readable non-transitory storage media including instructions operable, when executed by at least one processor, to cause an acoustic feedback (AFB) mitigator to mitigate AFB between an acoustic transducer and an acoustic sensor, the instructions, when executed, causing the AFB mitigator to generate a first filtered signal by filtering a first input signal with a first filter, the first input signal based on a transducer acoustic pattern output by the acoustic transducer, and to generate a second filtered signal by filtering the first input signal with a second filter, the second filter including an adaptive filter adapted based on a difference between the AFB mitigated signal and the second filtered signal, the AFB mitigated signal based on a difference between the second input signal and the first filtered signal, the second input signal based on a sensor acoustic pattern sensed by the acoustic sensor.

[0537] Example 26 includes the subject matter of Example 25, and optionally, the instructions, when executed, cause the AFB mitigator to perform one or more operations according to any of Examples 1-24.

[0538] Example 27 includes a method that includes mitigating acoustic feedback (AFB) between an acoustic transducer and an acoustic sensor, where the mitigating AFB includes: generating a first filtered signal by filtering a first input signal with a first filter, where the first input signal is based on a transducer acoustic pattern output by the acoustic transducer; and generating a second filtered signal by filtering the first input signal with a second filter, where the second filter includes an adaptive filter that is adapted based on a difference between the AFB-mitigated signal and the second filtered signal, where the AFB-mitigated signal is based on a difference between the second input signal and the first filtered signal, where the second input signal is based on a sensor acoustic pattern sensed by the acoustic sensor.

[0539] Example 28 includes the subject matter of Example 27 and optionally includes one or more operations according to any of Examples 1-24.

[0540] Example 29 includes an audio control system including the device of any one of Examples 1 to 24.

[0541] Example 30 includes a device including at least one acoustic sensor, at least one acoustic transducer, and any of the apparatus of Examples 1-24.

[0542] Example 31 includes an apparatus including means for performing any of the described operations of any of Examples 1-24.

[0543] Example 32 includes an apparatus including a memory interface and a processing circuit configured to perform any of the described operations of any of Examples 1-24.

[0544] Example 33 includes a method including any of the described operations of any of Examples 1-24.

[0545] Any features, operations, components and / or features described herein with reference to one or more embodiments may be combined or utilized in combination with one or more other features, operations, components and / or features described herein with reference to one or more other embodiments, and vice versa.

[0546] While certain features have been illustrated and described herein, many modifications, substitutions, changes, and equivalents may occur to those skilled in the art. It is therefore understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present disclosure.

Claims

1. An apparatus, comprising:

1. An acoustic feedback (AFB) mitigator configured to mitigate acoustic feedback (AFB) between an acoustic transducer and an acoustic sensor, the AFB mitigator comprising: a first filter configured to generate a first filtered signal by filtering a first input signal, the first input signal being based on a transducer acoustic pattern output by the acoustic transducer; and a second filter configured to generate a second filtered signal by filtering the first input signal, the second filter comprising an adaptive filter adapted based on a difference between an AFB-mitigated signal and the second filtered signal, the AFB-mitigated signal being based on a difference between a second input signal and the first filtered signal, and the second input signal being based on a sensor acoustic pattern sensed by the acoustic sensor; and An AFB mitigator comprising: An apparatus comprising:

2. The apparatus of claim 1 , wherein the first filter comprises a fixed filter having a fixed filter function.

3. The apparatus of claim 2 , wherein the fixed filter function is based on a predefined acoustic configuration of a system comprising the acoustic transducer and the acoustic sensor.

4. The apparatus of claim 2 , wherein the fixed filter function is based on a predefined acoustic configuration between the acoustic transducer and the acoustic sensor.

5. The apparatus of claim 2, comprising: a first subtractor for generating a first AFB-mitigated signal by subtracting the first filtered signal from the second input signal; and a second subtractor for generating a second AFB-mitigated signal by subtracting the second filtered signal from the first AFB-mitigated signal, wherein the second filter is adapted based on a difference between the first AFB-mitigated signal and the second filtered signal.

6. 6. The apparatus of claim 5, wherein the first input signal is based on an output of a predictive filter, the input of the predictive filter being based on the second AFB-mitigated signal.

7. The apparatus of claim 2, further comprising: a third filter configured to generate a third filtered signal by filtering the first input signal, the third filter comprising another adaptive filter adapted based on subtraction of a filtered predefined signal from a difference between the AFB-mitigated signal and the second filtered signal, the filtered predefined signal comprising a predefined signal filtered by the third filter.

8. The apparatus of claim 7 , wherein the predefined signal comprises a noise signal.

9. The apparatus of claim 7 , wherein the frequency spectrum of the predefined signal is different from the frequency spectrum of the first input signal.

10. an adder for adding the filtered predefined signal to the second input signal to generate a modified sensor signal; a first subtractor for generating a first AFB-mitigated signal by subtracting the first filtered signal from the modified sensor signal; a second subtractor for generating a second AFB-mitigated signal by subtracting a sum of filtered signals from the first AFB-mitigated signal, the sum of filtered signals comprising a sum of the third filtered signal and the filtered predefined signal; The apparatus of claim 7, comprising:

11. The apparatus of claim 10 , wherein the first input signal is based on an output of a predictive filter, the input of the predictive filter being based on the second AFB-mitigated signal.

12. 2. The apparatus of claim 1, wherein the first filter comprises another adaptive filter adapted based on subtraction of a filtered predefined signal from a difference between the AFB-mitigated signal and the second filtered signal, the filtered predefined signal comprising the predefined signal filtered by the first filter.

13. The apparatus of claim 12 , wherein the predefined signal comprises a noise signal.

14. The apparatus of claim 12 , wherein the frequency spectrum of the predefined signal is different from the frequency spectrum of the first input signal.

15. an adder for adding the filtered predefined signal to the second input signal to generate a modified sensor signal; a first subtractor for subtracting the first filtered signal from the modified sensor signal to generate a first AFB-mitigated signal; a second subtractor for subtracting the filtered predefined signal from the first AFB-mitigated signal to generate a second AFB-mitigated signal; The apparatus of claim 12, comprising:

16. 16. The apparatus of claim 15, wherein the first input signal is based on an output of a predictive filter, the input of the predictive filter being based on the second AFB-mitigated signal.

17. 2. The apparatus of claim 1, wherein the first filter is configured to generate a first filtered signal comprising a first estimate of the AFB, and the second filter is configured to generate a second filtered signal comprising a second estimate of the AFB.

18. The apparatus of claim 1 , wherein the second filter is configured to generate the second filtered signal based on a change in the AFB.

19. The apparatus of claim 1, comprising a predictive filter (PF) configured to generate a PF output based on a PF input of an active acoustic control (AAC) system comprising the acoustic transducer and the acoustic sensor, wherein the first input signal is based on the PF output and the PF input is based on the AFB-mitigated signal.

20. 20. The apparatus of claim 19, wherein the first input signal is based on a combination of the PF output and at least one of an audio signal and a voice signal.

21. The apparatus of claim 1 , wherein the first input signal is based on at least one of an audio signal and a voice signal.

22. The apparatus of claim 1 , wherein the second filter is adapted based on a least mean squares (LMS) algorithm or an LMS algorithm variant.

23. The apparatus of claim 1 , wherein at least one of the first filter and the second filter is a finite impulse response (FIR) filter.

24. The apparatus of claim 1 , wherein at least one of the first filter and the second filter is an infinite impulse response (IIR) filter.

25. A device comprising: at least one acoustic sensor; at least one acoustic transducer; 25. The apparatus of claim 1, further comprising an AFB mitigator for mitigating AFB between the acoustic transducer and the acoustic sensor; A device comprising:

26. A sound control system comprising a device according to any one of claims 1 to 24, the sound control system comprising: one or more acoustic transducers; one or more acoustic sensors for generating one or more acoustic sensor signals representative of sound at one or more sensing locations; a controller configured to determine a sound control pattern for controlling sound within a sound control zone and output the sound control pattern to the one or more acoustic transducers, the controller configured to determine the sound control pattern based on the one or more acoustic sensor signals, the controller comprising an AFB mitigator configured to mitigate AFB between at least one acoustic transducer of the one or more acoustic transducers and at least one acoustic sensor of the one or more acoustic sensors; An acoustic control system comprising:

27. A method for mitigating acoustic feedback (AFB) between an acoustic transducer and an acoustic sensor, the method comprising: generating a first filtered signal by filtering a first input signal with a first filter, the first input signal being based on a transducer acoustic pattern output by the acoustic transducer; generating a second filtered signal by filtering the first input signal with a second filter, the second filter comprising an adaptive filter adapted based on a difference between an AFB-mitigated signal and the second filtered signal, the AFB-mitigated signal being based on a difference between the second input signal and the first filtered signal, and the second input signal being based on a sensor acoustic pattern sensed by the acoustic sensor; A method comprising:

28. The method of claim 27, wherein the first filter comprises a fixed filter having a fixed filter function.

29. The method described in claim 27, wherein the first filter comprises another adaptive filter adapted based on subtraction of a filtered predefined signal from the difference between the AFB-mitigated signal and the second filtered signal, and the filtered predefined signal comprises a predefined signal filtered by the first filter.

30. A product comprising one or more tangible computer-readable persistent storage media comprising instructions which, when executed by at least one processor, are operable to cause acoustic feedback (AFB) mitigation in accordance with a method according to any one of claims 27 to 29.

31. An apparatus comprising means for carrying out the method according to any one of claims 27 to 29.

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