VEHICLE AUDIO SYSTEM AND METHOD FOR PROCESSING AUDIO SIGNALS IN A VEHICLE INTERIOR

Abstract

An example of a vehicle audio system includes a vehicle speaker configured to generate audio signals, a plurality of microphones, and a vehicle control module configured to: receive an input signal via the plurality of microphones, split the input signal into a parallel-domain signal and an orthogonal-domain signal, select a constant step size value for an orthogonal-domain filter weight and a variable step size value for a parallel-domain filter weight, adjust the orthogonal-domain filter weight according to the orthogonal-domain signal and the constant step size value, adjust the parallel-domain filter weight according to the parallel-domain signal and the variable step size value, combine the adjusted orthogonal-domain filter weight and the adjusted parallel-domain filter weight to define a total filter weight, and apply the total filter weight to the received input signal,to perform a signal processing operation on the received input signal.,

Description

INTRODUCTION

[0001] The present invention relates generally to a vehicle audio system, including audio signal processing using parallel and orthogonal domain filter weights, and to a method for processing audio signals in a vehicle interior.

[0002] US 2007 / 0274535 A1 discloses an audio system comprising a loudspeaker configured to generate audio signals, a microphone configured to receive audio signals, and a control module configured to: receive an input signal via the microphone and split it into a first signal and a second signal; select a variable step size value for a filter weight and adjust it according to the first signal, the second signal, and the step size value; and apply the filter weight to the received input signal to perform a signal processing operation on the received input signal prior to audio output of the received input signal. Further prior art can also be found in EP 2 675 073 B1.

[0003] During a telephone conversation, a double-talk scenario can occur when both a far-end and a nearby party are speaking simultaneously. During a double-talk event, an acoustic echo canceller in a speech processing chain may converge to an incorrect solution, resulting in artifacts such as the cancellation of a desired signal, musical tones, and a reverberation effect at the acoustic echo canceller's output, where the original sound is heard along with a delayed version of the same sound. SUMMARY

[0004] According to the invention, a vehicle audio system is presented which is characterized by the features of claim 1.

[0005] The vehicle audio system includes at least one vehicle speaker configured to generate audio signals within the interior of a vehicle, a plurality of microphones each configured to receive audio signals within the interior of the vehicle, and a vehicle control module configured to: receive an input signal via the plurality of microphones, split the input signal received via the plurality of microphones into a parallel domain signal and an orthogonal domain signal.Orthogonal-domain signal, selecting a constant step size value for an orthogonal-domain filter weight and a variable step size value for a parallel-domain filter weight, adjusting the orthogonal-domain filter weight according to the orthogonal-domain signal and the constant step size value, adjusting the parallel-domain filter weight according to the parallel-domain signal and the variable step size value, combining the adjusted orthogonal-domain filter weight and the adjusted parallel-domain filter weight to define a total filter weight, and applying the total filter weight to the received input signal to perform a signal processing operation on the received input signal prior to audio output of the received input signal.

[0006] In some examples, the vehicle control module is configured to control the at least one vehicle speaker to output an audio signal based on the input signal modified by the total filter weight.

[0007] In some examples, the vehicle control module is configured to split the input signal into the parallel domain signal and the orthogonal domain signal to apply a parallel projection to the input signal received via the plurality of microphones and apply an orthogonal projection to the input signal received via the plurality of microphones.

[0008] In some examples, the vehicle control module is configured to obtain a source signal control vector according to a beamforming parameter and / or a particular tuning state parameter and calculate the parallel projection and the orthogonal projection based on the source signal control vector.

[0009] In some examples, the parallel projection is defined parallel to a near-end target audio source. In some examples, the orthogonal projection is defined orthogonal to a near-end target audio source.

[0010] In some examples, the vehicle control module is configured to apply a larger value for the variable step size during a first period in which a double-talk condition is present in the input signal than during a second period in which the double-talk condition is present in the input signal.

[0011] In some examples, the vehicle control module is configured to perform an acoustic echo canceller (AEC) operation to determine a residual echo value by subtracting a product of the total filter weight and a reference signal from the input signal received via the plurality of microphones.

[0012] In some examples, the vehicle control module is configured to adjust the orthogonal-domain filter weight and the parallel-domain filter weight using at least one of the following methods: normalized least mean squares (NLMS), recursive least squares (RLS), or an affine projection. In some examples, the plurality of microphones are arranged in a linear array within the vehicle.

[0013] According to the invention, a method for processing audio signals in a vehicle interior is further presented, which is characterized by the features of claim 10.

[0014] The method comprises: receiving an input signal from a plurality of microphones by a vehicle control module, each of the plurality of microphones being configured to receive audio signals in an interior of a vehicle, splitting the input signal received via the plurality of microphones into a parallel domain signal and an orthogonal domain signal, selecting a constant step size value for an orthogonal domain filter weight and a variable step size value for a parallel domain filter weight, adjusting the orthogonal domain filter weight according to the orthogonal domain signal and the constant step size value, adjusting the parallel domain filter weight according to the parallel domain signal and the variable step size value, combining the adjusted orthogonal domain filter weight and the adjusted parallel domain filter weight to define a total filter weight,and applying the total filter weight to the received input signal to perform a signal processing operation on the received input signal prior to audio output of the received input signal.

[0015] In some examples, the method includes controlling at least one vehicle speaker to output an audio signal based on the input signal modified by the total filter weight.

[0016] In some examples, separating the input signal into the parallel domain signal and the orthogonal domain signal comprises applying a parallel projection to the input signal received via the plurality of microphones and applying an orthogonal projection to the input signal received via the plurality of microphones.

[0017] In some examples, the method comprises: obtaining a source signal steering vector corresponding to a beamformer parameter and / or a particular tuning state parameter; and calculating the parallel projection and the orthogonal projection based on the source signal steering vector.

[0018] In some examples, the parallel projection is defined parallel to a near-end target audio source. In some examples, the orthogonal projection is defined orthogonal to a near-end target audio source.

[0019] In some examples, adjusting the parallel domain filter weight includes applying a larger variable step size value during a first time period in which a doubletalk condition is present in the input signal compared to a second time period in which the doubletalk condition is present in the input signal.

[0020] In some examples, the method includes performing an acoustic echo canceller (AEC) operation to determine a residual echo value by subtracting a product of the total filter weight and a reference signal from the input signal received via the plurality of microphones.

[0021] In some examples, adjusting the orthogonal-domain filter weight and adjusting the parallel-domain filter weight includes using at least one of the following methods: normalized least mean squares (NLMS), recursive least squares (RLS), or affine projection. In some examples, the plurality of microphones are arranged in a linear array within the vehicle.

[0022] Further areas of applicability of the present invention will become apparent from the detailed description, claims, and drawings. The detailed description and specific examples are provided for illustrative purposes only. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The present invention will become more fully apparent from the detailed description and the accompanying drawings, in which: Fig. 1 is a diagram of an example vehicle with a vehicle audio system. Fig. Figure 2 is a block diagram showing an example of a signal processing system with an audio echo canceller. Fig. 3 is a block diagram illustrating exemplary signals in the signal processing system of Fig. 2 shows. Fig. 4 is a flowchart illustrating an exemplary process for processing audio signals using a parallel domain signal and an orthogonal domain signal. Fig. Figure 5 is a flowchart illustrating an exemplary process for determining variable step size values ​​for the process of Fig. 4 represents.

[0024] Reference numbers may be reused in the drawings to identify similar and / or identical elements. DETAILED DESCRIPTION

[0025] In some examples, a signal processing chain may include an acoustic echo canceller (AEC), e.g., for processing audio signals from the vehicle interior. During a telephone conversation, a double-talk (DT) scenario occurs when both the far-end (FE) and near-end (NE) speakers speak simultaneously. During the double-talk scenario, the adaptation by the AEC's adaptive filter (AF) can be reduced or stopped to prevent or avoid the adaptive filter from converging to an incorrect solution. This could lead to suboptimal convergence and, consequently, an incorrect solution, which can cause artifacts such as cancellation of a desired signal, musical tones, and a reverberation effect at the AEC output.

[0026] In some embodiments, knowledge of the location of the desired near-end source can be used to split the AEC filter into two domains, one parallel to the desired source and another orthogonal to the desired near-end source. The orthogonal domain can be adjusted with few or no restrictions, even during a DT condition, because the orthogonal-domain signal may not contain desired speech (e.g., because the domain is orthogonal to the near-end source). Double talk detection may be easier in the parallel domain compared to the original domain because signal-to-echo ratios (SERs) are higher in the parallel domain (e.g., because the orthogonal-domain signal has been extracted from the parallel-domain signal).

[0027] In Fig. 1 shows a vehicle 10 with front wheels 12 and rear wheels 13. A drive unit 14 delivers Fig. 1 selectively delivers torque to the front wheels 12 and / or the rear wheels 13 via drive lines 16 and 18, respectively. The vehicle 10 may include various types of drive units. The vehicle may, for example, be an electric vehicle such as a battery electric vehicle (BEV), a hybrid vehicle, a fuel cell vehicle, an internal combustion engine (ICE), or another vehicle type.

[0028] Some examples of the drive unit 14 may include any suitable electric motor, an inverter, and a motor controller configured to control power switches within the inverter to adjust motor speed and torque during propulsion and / or regeneration. The battery system supplies or receives power from the electric motor of the drive unit 14 via the inverter during propulsion or regeneration.

[0029] While the vehicle 10 in Fig. 1 includes a drive unit 14, the vehicle 10 may also have other configurations. For example, two separate drive units may drive the front wheels 12 and the rear wheels 13, one or more separate drive units may drive individual wheels, etc. It is understood that other vehicle configurations and / or drive units may also be used.

[0030] The vehicle control module 20 may be configured to control the operation of one or more vehicle components, such as the drive unit 14 (e.g., by controlling the torque settings of an electric motor of the drive unit 14). The vehicle control module 20 may receive inputs to control components of the vehicle, e.g., signals from a steering wheel, an accelerator pedal, a brake pedal, etc. The vehicle control module 20 may monitor the vehicle's telematics data for safety purposes, e.g., vehicle speed, vehicle location, vehicle braking and acceleration, etc.

[0031] The vehicle control module 20 may receive signals from any suitable components for monitoring one or more aspects of the vehicle, including one or more vehicle sensors (e.g., cameras, microphones, pressure sensors, steering wheel position sensors, brake sensors, position sensors such as GPS antennas, wheel height and / or position sensors, accelerometers, etc.). Some sensors may be configured to monitor the current movement of the vehicle, the vehicle's acceleration, the vehicle's deceleration, the current steering direction of the vehicle, the current height and / or position of one or more wheels, etc.

[0032] In some examples, vehicle microphones 22 are configured to capture audio signals from the interior of the vehicle 10. For example, multiple microphones (e.g., at least two microphones, at least four microphones, at least eight microphones, etc.) may be disposed within the interior of the vehicle 10, one or more devices located within the interior of the vehicle 10 may include microphones, etc. The vehicle microphones 22 may, in some examples, be formed in a linear array and may include any suitable microphone structure or component capable of capturing and transmitting audio signals (e.g., converting acoustic-mechanical audio signals into an electrical signal).

[0033] The vehicle 10 includes a plurality of vehicle speakers 24 that may be configured to generate audio signals within the interior of the vehicle 10. For example, a passenger or driver of the vehicle may use the vehicle microphones 22 and the vehicle speakers 24 to conduct a conversation (e.g., a hands-free telephone conversation), in which the vehicle microphones 22 capture the speech of the passenger or driver and the vehicle speakers 24 generate audio signals based on the speech of another person at the other end of the telephone conversation (which may be referred to as a far-end (FE) signal).

[0034] The vehicle control module 20 may communicate with another device via a wireless communication interface, which may include one or more wireless antennas for transmitting and / or receiving wireless communication signals. For example, the wireless communication interface may communicate via any suitable wireless communication protocol, including, but not limited to, vehicle-to-everything (V2V) communication, Wi-Fi communication, wireless area network (WAN) communication, cellular communication, personal area network (PAN) communication, short-range wireless communication (e.g., Bluetooth), etc. The wireless communication interface may communicate with a remote computing device via one or more wireless and / or wired networks.With regard to vehicle-to-vehicle (V2X) communication, the vehicle 10 may include one or more V2X transceivers (e.g., V2X signal transmitting and / or receiving antennas).

[0035] Fig. Figure 2 is a block diagram showing an example of a signal processing system 200 including an acoustic echo canceller 202. A call may be made between a far-end audio source 204 (e.g., a speaker at the other end of a telephone conversation) and a near-end audio source 206 (e.g., an occupant of a vehicle such as a driver or passenger). Although Fig. 2 is described with reference to a vehicle, other examples may also be used in environments other than a vehicle.

[0036] As in Fig. As shown in Figure 2, system 200 may include a speaker 208 (e.g., a vehicle interior speaker) configured to generate an audio signal based on an input signal from the far-end audio source 204. For example, the speech of a far-end speaker may be converted by the speaker 208 from an electrical signal into an acoustic mechanical sound signal audible to the vehicle occupants.

[0037] The system 200 includes a plurality of microphones 210. The microphones 210 may be configured to receive audio signals from the interior of the vehicle. For example, the microphones 210 may receive audio signals from the near-end audio source 206 and convert acoustic-mechanical sounds (e.g., the speech of vehicle occupants) into electrical audio signals.

[0038] The microphones 210 may include any suitable microphone components and arrangements, e.g., a linear array of microphones. Although Fig. 2 shows an arrangement of four microphones, other embodiments may include more or fewer microphones (e.g., at least two microphones, at least eight microphones, etc.), and the microphones may be arranged differently with respect to each other and within the vehicle interior.

[0039] The microphones 210 can record audio signals from the loudspeaker 208, as in Fig. 2. For example, the microphones 210 may be primarily configured to pick up speech from the nearby audio source 206 (e.g., the vehicle occupant speaker), but other sounds may also occur in the vehicle interior that are not intended to be picked up by the microphones 210.

[0040] As in Fig. As shown in Figure 2, a speech processing chain may be used to at least partially remove the audio signal from speaker 208 in the signal received by microphones 210. The speech processing chain may include any suitable speech processing elements, e.g., an acoustic echo canceller 202, a beamformer 212, etc. These components may be part of a vehicle control module in some embodiments.

[0041] Fig. 3 is a block diagram illustrating exemplary signals in the signal processing system of Fig. 2 shows. In the example diagram of Fig. 3, Z represents an output residual echo, D is the input signal (e.g., received from the audio source 204 at the far end), X is a reference signal, and W represents adaptive filter weights. In this example, an AEC operation can be: Z=D−WHX

[0042] When no speech from the nearby audio source 206 is active, the AEC can use the following equation to adjust the adaptive filter weights W: Wopt=argminwE{|Z|2}=R−1P where R is a reference autocorrelation matrix R = E{XX H} and P a cross-correlation matrix P = E{XD H} is.

[0043] In some examples, an optimal adaptive filter weight W opt be divided into two areas: W ∥ , which is parallel to the nearby audio source 206, and W ⊥ , which is orthogonal to the nearby audio source 206. For example: Wopt=W∥+W⊥

[0044] For separate adjustment, parallel and orthogonal projections T ∥ and T ⊥ applied to the input signal D: D∥=T∥D; D⊥=T⊥D where T ∥ and T ⊥are defined as parallel and orthogonal projection functions, respectively. A control vector S of the desired source can be used to determine the parallel and orthogonal projections T ∥ or T ⊥ The desired near-end control signal S can be determined in any suitable way, e.g., by using available parameters of the beamformer 212, by calculation in a pre-tuning phase, etc. An example of a parallel and orthogonal projection matrix for a single-order control vector S is: T∥=SSHSHS;T⊥=I−T∥

[0045] For the solution of W ∥ and W ⊥ Any suitable adaptive algorithm can be used, e.g. normalized least mean squares (NLMS), recursive least squares (RLS), affine projection (APA), etc. Using NLMS as an example, an adaptive iteration step can be: W(n+1)=W(n)+μX(n)Z*(n) / ‖X(n)‖2

[0046] Where µ is the adaptive step size, also called the learning rate. The learning rate determines the duration of the epoch. Since the desired signal at the near end may not be present in D ⊥ is present, the following example equation can be used to calculate W ⊥ with a constant adaptive step size µ ⊥ to solve, achieving fast and deep convergence: W⊥(n+1)=W⊥(n)+μ⊥X(n)Z⊥*(n)‖X(n)‖2

[0047] Since the near end signal in D ∥ may be present, a variable step size (VSS or variable step size) µ ∥ (n) to solve W ∥ used to W ∥ to protect against divergence: W∥(n+1)=W∥(n)+μ∥(n)X(n)Z∥*(n)‖X(n)‖2

[0048] In some examples, higher µ ∥(n) values ​​can be chosen or used for situations where there is no double talk, which allows for fast convergence. If double talk is present, lower µ ∥ (n) values ​​should be selected or used and adjusted accordingly to avoid filter divergences. µ ∥ (n) values ​​can be estimated in any suitable way, e.g. based on the energy levels of X(n), the correlation between X(n) and D ∥ (n), the directional dependence of Z ∥ (n), etc.

[0049] Due to the projection T ∥ the echo values ​​in D ∥ lower and the SER values ​​higher than in D, which makes the estimate of µ ∥ (n). This can reduce the number of false detections, achieve faster convergence, and produce better speech quality. These concepts can also be used in other adaptive algorithms.

[0050] The adaptive algorithm, optimization criteria, rule set, etc., can be selected based on their suitability for orthogonal and parallel models. These options can be selected based on system identification techniques, for example. If these features qualify as autoregressive moving average (ARMA) models, a more appropriate rule set can be selected based on the system parameterization.

[0051] As in Fig. As shown in Figure 3, the element G can be an impulse response. The adaptive filter weights W can, for example, be G in the optimal case. The reference signal X can represent a tone reproduced in the loudspeaker 208, and the system 200 can attempt to cancel the reference signal X (e.g., with the goal of eliminating the reference signal). For example, the reference signal X can be multiplied by the adaptive filter weights W, resulting in a signal Y that can then cancel the echo signal present in D.

[0052] Although the element G may be unknown, the system 200 can be configured to determine the element G. S may represent an acoustic function between the nearby audio source 206 and the microphones 210 and may not necessarily include the speech itself. The acoustic function S may depend, for example, on the position of the speaker's mouth relative to the microphones 210.

[0053] Fig. Figure 4 is a flowchart illustrating an exemplary process for processing audio signals using a parallel-domain signal and an orthogonal-domain signal. The process may be performed, for example, by the vehicle control module 20 of Fig. 1. At 304, the process begins by receiving an input signal via multiple microphones, such as the vehicle microphones 22 of the vehicle 10 in Fig. 1 or the microphones 210 in Fig. 2 and Fig. 3.

[0054] At 408, the controller splits the input signal into a parallel-domain signal and an orthogonal-domain signal. The controller then selects a constant step size value for the orthogonal-domain filter weight and a variable step size value for the parallel-domain filter weight at 412.

[0055] At 416, the vehicle control module is configured to adjust the orthogonal range filter weight according to the orthogonal range signal and the constant step size value. Example details for adjusting the orthogonal range filter weight are described above with reference to Fig. 2 and Fig. 3 described.

[0056] The vehicle control module is configured to adjust the parallel-domain filter weight according to the parallel-domain signal and the variable step size value at 420. Further details regarding the parallel-domain filter weight adjustment are described above with reference to Fig. 2 and Fig. 3 and further below with reference to the example in Fig. 5 described.

[0057] At 424, the controller is configured to combine the adjusted orthogonal and parallel-domain filter weights to form a total filter weight. The total filter weight is then applied to the received input signal at 428. For example, the vehicle control module may be configured to generate an output audio signal based on the received input signal after modifying the input signal based on the adjusted filter weights.

[0058] Fig. Figure 5 is a flowchart illustrating an exemplary process for determining variable step size values ​​for the process of Fig. 4. The process can be carried out, for example, by the vehicle control module 20 Fig.1. At 504, the process begins by determining the value of the parallel domain filter weight for a current time step (e.g., a value currently used for adaptive filtering of the parallel domain signal).

[0059] Control then determines at 508 whether a double-talk audio signal is present (e.g., by using suitable sensors and / or signal processing techniques to determine or detect double-talk). If the double-talk condition is met at 508, control proceeds to 512 to select a first value for the variable step size.

[0060] If the double talk condition is not met at 508, control continues to 516 to select a second variable step size value that is larger than the first value. This allows the vehicle control module to use smaller step sizes for adjustment when the double talk condition is met and larger step sizes when the double talk condition is not met. At 520, control calculates an updated parallel domain filter weight value using the selected step size value.

[0061] As described above, in some examples, the input signal is split into two regions (orthogonal and parallel to the desired source), and different adaptations are made in each region. For example, in the orthogonal region, the desired source (e.g., the near-end speaker) may not be present, or only residuals may be present. A constant learning rate step size can be used when there is no need to interrupt the adaptation because the desired speaker is not present in the orthogonal signal.

[0062] In the parallel domain, the desired source may be present, but the echo values ​​are different (e.g., when the orthogonal domain signal is removed). A variable step size can be used, choosing a larger value when the desired speaker is absent and a smaller value (or zero) when the desired speaker is present. The desired speaker may refer to a speaking person whose speech the system should transmit but cancel any echo. For example, the adaptive filter should ignore the desired source (e.g., a person in the vehicle speaking into the microphone array) but continue to filter the echo even when the desired source is speaking.

[0063] Splitting the input signal into two dimensions allows one to proceed in the orthogonal domain without regard to the desired source (e.g. because the desired source may not be present in the orthogonal domain signal), while in the parallel domain a lower echo is to be expected, making the presence of double-talk scenarios easier to detect.

[0064] Although some of the embodiments described herein relate to vehicle interiors and vehicle microphones and speakers, the signal processing techniques may also be used in other suitable environments, e.g., in a room or when playing music through a speaker while attempting to speak through a smartphone (e.g., when there is a desire to mute the music while the smartphone hears the speaker's voice). In some examples, the techniques described herein may change the learning rate of the adaptation while filtering is applied constantly or as needed to the input signals. The adaptive filter may use polynomial fitting, weights that fit a recursive equation, etc. Figure description of Fig. 5 Y Yes N No

Claims

[1] Vehicle audio system (200), comprising: at least one vehicle loudspeaker (208) configured to generate audio signals in the interior of a vehicle (10); a plurality of microphones (210), each configured to receive audio signals in the interior of the vehicle (10); and a vehicle control module (20) configured to: Receiving an input signal via the plurality of microphones (210); splitting the input signal received via the plurality of microphones (210) into a parallel domain signal and an orthogonal domain signal; Selecting a constant step size value for an orthogonal domain filter weight and a variable step size value for a parallel domain filter weight; Adjusting the orthogonal range filter weight according to the orthogonal range signal and the constant step size value; Adjusting the parallel-domain filter weight according to the parallel-domain signal and the variable step size value; Combining the adjusted orthogonal domain filter weight and the adjusted parallel domain filter weight to define a total filter weight; and Applying the total filter weight to the received input signal to perform a signal processing operation on the received input signal before outputting the audio of the received input signal. [2] The vehicle audio system (200) of claim 1, wherein the vehicle control module (20) is configured to control the at least one vehicle speaker (208) to output an audio signal based on the input signal modified by the total filter weight. [3] The vehicle audio system (200) of claim 1, wherein the vehicle control module (20) is configured to split the input signal into the parallel domain signal and the orthogonal domain signal by: applying a parallel projection to the input signal received via the plurality of microphones (210); and Applying an orthogonal projection to the input signal received via the plurality of microphones (210). [4] The vehicle audio system (200) of claim 3, wherein the vehicle control module (20) is configured to: Obtaining a source signal control vector according to a beamforming parameter and / or a particular tuning state parameter; and Calculate the parallel projection and the orthogonal projection based on the source signal control vector. [5] The vehicle audio system (200) of claim 3, wherein the parallel projection is defined parallel to a near-end target audio source. [6] The vehicle audio system (200) of claim 3, wherein the orthogonal projection is defined orthogonally to a near-end target audio source. [7] The vehicle audio system (200) of claim 1, wherein the vehicle control module (20) is configured to apply a larger step size value during a first period in which a double-talk condition is present in the input signal than during a second period in which the double-talk condition is present in the input signal. [8] The vehicle audio system (200) of claim 1, wherein the vehicle control module (20) is configured to perform an acoustic echo canceller (AEC) operation to determine a residual echo value by subtracting a product of the total filter weight and a reference signal from the input signal received via the plurality of microphones (210). [9] The vehicle audio system (200) of claim 1, wherein the vehicle control module (20) is configured to adjust the orthogonal domain filter weight and the parallel domain filter weight using at least one of the following projections: normalized least mean squares (NLMS), recursive least squares (RLS), or an affine projection. [10] A method for processing audio signals in a vehicle interior, the method comprising: Receiving an input signal from a plurality of microphones (210) by a vehicle control module (20), each of the plurality of microphones (210) configured to receive audio signals in an interior of a vehicle (10); splitting the input signal received via the plurality of microphones (210) into a parallel domain signal and an orthogonal domain signal; Selecting a constant step size value for an orthogonal domain filter weight and a variable step size value for a parallel domain filter weight; Adjusting the orthogonal range filter weight according to the orthogonal range signal and the constant step size value; Adjusting the parallel-domain filter weight according to the parallel-domain signal and the variable step size value; Combining the adjusted orthogonal domain filter weight and the adjusted parallel domain filter weight to define a total filter weight; and Applying the total filter weight to the received input signal to perform a signal processing operation on the received input signal before audio output of the received input signal.

Images