KR20240009758A - A method of online beamforming and steering vector estimation based on target masks and ICA for robust speech recognition - Google Patents

Abstract

The beamforming and direction vector estimation system according to an embodiment of the present invention may include an input providing unit, a demixing providing unit, and a result providing unit. The input provider may provide input signals from microphones based on a spatial transfer function corresponding to the target signal and noise signal at the target point. The demixing provider may provide a demixing matrix determined according to independent component analysis (ICA) with spatial constraints and input signals from microphones. The result provider may extract result signals from input signals from microphones based on the demixing matrix.
In the beamforming and direction vector estimation system according to the present invention, by calculating a demixing matrix using a cost function including a plurality of constraint conditions, the target signal generated from the target point can be extracted fixedly and without distortion to the desired channel. .

Description

Real-time beamforming and steering vector estimation method based on target masks and ICA for robust speech recognition {A method of online beamforming and steering vector estimation based on target masks and ICA for robust speech recognition}

The present invention relates to a beamforming and direction vector estimation system for a target sound source in a speech recognition system. More specifically, beamforming and direction vector estimation system are performed by simultaneously considering models for the target sound source and noise based on a target mask and independent component analysis. This relates to a method that can improve performance for direction vector estimation.

Input signals from microphones input through microphones may include not only the target voice required for voice recognition but also noise that interferes with voice recognition. Various research is being conducted to improve voice recognition performance by removing noise from microphone input signals and extracting only desired target voices.

(Korean registered patent) No. 10-1133308 (registration date, March 28, 2012)

The technical problem to be achieved by the present invention is to provide a beamforming and direction vector estimation system that can extract a target signal generated from a target point without distortion by calculating a demixing matrix using a cost function that additionally includes a plurality of constraints. It is done.

In order to solve this problem, the beamforming and direction vector estimation system according to an embodiment of the present invention may include an input providing unit, a demixing providing unit, and a result providing unit. The input provider may provide input signals from microphones based on a spatial transfer function corresponding to the target signal and noise signal at the target point. The demixing provider may provide a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA). The result provider may extract a result signal from the input signals of the microphones based on the demixing matrix.

In one embodiment, the spatial transfer function is a direction vector corresponding to a transfer function from the target point to the input provider and a noise transfer function corresponding to a transfer function until the noise signal is transmitted to the input provider. may include.

In one embodiment, the demixing matrix The first ingredient included in and the direction vector included in the spatial transfer function The product of is 1, and the remaining components excluding the first component included in the demixing matrix and the direction vector The product of may be 0.

In one embodiment, the demixing matrix may be determined based on a cost function (CF) according to the independent component analysis.

In one embodiment, the first component of a result matrix generated based on the input signals of the microphones and the demixing matrix may correspond to the target signal.

In one embodiment, the cost function is expressed as [Equation 1],

[Equation 1]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, respectively, is the cost function of independent component analysis, and are parameters that control the degree of restriction of distortion prevention and null conditions, respectively, is the first component of the demixing matrix, may be a direction vector.

In one embodiment, the cost function is expressed as [Equation 2],

[Equation 2]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, respectively, and are the Lagrangian multipliers to prevent distortion and ensure null conditions, respectively; is the first component of the demixing matrix, may be a direction vector.

In one embodiment, the cost function is expressed as [Equation 3],

[Equation 3]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, respectively, is the Lagrangian multiplier to ensure the anti-distortion condition, is the first component of the demixing matrix, is the direction vector, may be a parameter that controls the degree of constraint of the null condition.

In one embodiment, the result signal with respect to the target signal may be distributed according to a Laplacian function.

In one embodiment, the direction vector is the difference between the spatial covariance matrix (Input Spatial Covariance Matrix, ISCM) for the input signals of the microphones and the spatial covariance matrix (Noise Spatial Covariance Matrix, NSCM) for the noise signals. It can be decided accordingly.

In one embodiment, the spatial covariance matrix for the noise signal may be determined according to the ratio of a value corresponding to the target signal and a value corresponding to the noise signal among the result signals.

In one embodiment, the beamforming and direction vector estimation system may be driven for each frame corresponding to a constant time interval to update the demixing matrix.

To solve this problem, the beamforming and direction vector estimation system according to an embodiment of the present invention may include an input providing unit, a demixing providing unit, a result providing unit, and a voice providing unit. The input provider may provide input signals from microphones based on a spatial transfer function corresponding to the target signal and noise signal at the target point. The demixing provider may provide a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA). The result provider may extract a result signal from the input signals of the microphones based on the demixing matrix. The voice provider may provide the result signal as a voice.

In order to solve this problem, in the method of operating the beamforming and direction vector estimation system according to an embodiment of the present invention, the input provider operates the microphones based on the spatial transfer functions corresponding to each of the target signal and noise signal at the target point. An input signal can be provided. The demixing provider may provide a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA). The result provider may extract a result signal from the input signals of the microphones based on the demixing matrix.

In order to solve this problem, in the method of operating the beamforming and direction vector estimation system according to an embodiment of the present invention, the input provider operates the microphones based on the spatial transfer functions corresponding to each of the target signal and noise signal at the target point. An input signal can be provided. The demixing provider may provide a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA). The result provider may extract a result signal from the input signals of the microphones based on the demixing matrix. The voice provider may provide the result signal as voice.

In addition to the technical problems of the present invention mentioned above, other features and advantages of the present invention are described below, or can be clearly understood by those skilled in the art from such description and description.

According to the present invention as described above, the following effects are achieved.

In the beamforming and direction vector estimation system according to the present invention, a target signal generated from a target point can be extracted without distortion by calculating a demixing matrix using a cost function including a plurality of constraint conditions. And the direction vector can be effectively estimated using values corresponding to the noise signal as well as the target signal.

In addition, other features and advantages of the present invention may be newly understood through embodiments of the present invention.

1 is a diagram illustrating a beamforming and direction vector estimation system according to embodiments of the present invention.
FIG. 2 is a diagram for explaining input signals from microphones applied to the beamforming and direction vector estimation system of FIG. 1.
FIG. 3 is a diagram for explaining the spatial transfer function used in the beamforming and direction vector estimation system of FIG. 1.
Figures 4 and 5 are diagrams for explaining the online operation of the beamforming and direction vector estimation system of Figure 1.
FIG. 6 is a diagram for explaining an embodiment of the beamforming and direction vector estimation system of FIG. 1.
Figure 7 is a diagram showing a method of operating a beamforming and direction vector estimation system according to embodiments of the present invention.
FIG. 8 is a diagram for explaining an embodiment of an operating method of the beamforming and direction vector estimation system of FIG. 7.

In this specification, it should be noted that when adding reference numbers to the components of each drawing, the same components are given the same number as much as possible even if they are shown in different drawings.

Meanwhile, the meaning of the terms described in this specification should be understood as follows.

Unless the context clearly defines otherwise, singular expressions should be understood to include plural expressions, and the scope of rights should not be limited by these terms.

Terms such as “include” or “have” should be understood as not precluding the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

Hereinafter, preferred embodiments of the present invention designed to solve the above problems will be described in detail with reference to the accompanying drawings.

1 is a diagram illustrating a beamforming and direction vector estimation system according to embodiments of the present invention, and 2 is a diagram illustrating input signals from microphones applied to the beamforming and direction vector estimation system of FIG. 1, and FIG. 3 is a diagram to explain the spatial transfer function used in the beamforming and direction vector estimation system of FIG. 1.

Referring to FIGS. 1 to 3, the beamforming and direction vector estimation system 10 according to an embodiment of the present invention may include an input providing unit 100, a demixing providing unit 200, and a result providing unit 300. You can. The input provider 100 may provide input signals (XS) from microphones based on a spatial transfer function (A) corresponding to the target signal (TS) and noise signal (NS) at the target point (TP). For example, the input providing unit 100 may be a plurality of microphones. The plurality of microphones may include a first microphone 101 to a third microphone 103. The spatial transfer function (A) is a direction vector (Steering Vector) (H) and noise signal (NS) corresponding to the transfer function until the target signal (TS) is transferred from the target point (TP) to the input provider 100. It may include a noise transfer function (D) corresponding to the transfer function until the noise is transmitted to the input providing unit 100. In this case, the input signal (XS) of the microphones can be expressed as [Equation 1-1] as follows.

[Equation 1-1]

,

here, is the input signal of the microphones (XS), is the spatial transfer function (A), is the target signal (TS), is the noise signal (NS), direction vector (H), is the noise transfer function (D), is the frequency index, may be a frame index.

The demixing provider 200 may provide a demixing matrix (W) determined according to input signals (XS) of microphones and independent component analysis (ICA).

In one embodiment, the demixing matrix (W) may be determined based on independent component analysis and a cost function (CF) according to space constraints. The space constraint condition is a distortion prevention condition ( ) and null condition ( ) can be expressed as For example, the cost function can be expressed as [Equation 1], [Equation 2], and [Equation 3] below.

[Equation 1]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, respectively, is the cost function of independent component analysis, and are parameters that control the degree of restriction of distortion prevention and null conditions, respectively. and are the first and m components of the demixing matrix (W), may be a direction vector (H). Meanwhile, the cost function The existing cost function of the basic independent component analysis that constitutes Can be expressed as [Equation 1-2] below.

[Equation 1-2]

where k and m are natural numbers representing the frequency and channel index, and are the first and m components of the demixing matrix (W), is the demixing matrix (W), and may represent a Weighted Spatial Covariance Matrix (WSCM) determined according to modeling of the target signal and the noise signal, respectively. The first component of the demixing matrix (W) that optimizes [Equation 1] Can be repeatedly estimated to converge using [Equation 1-3] below.

[Equation 1-3]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the target signal, is a parameter that controls the degree of constraint of the distortion prevention condition, is the direction vector (H), May be the first component of the demixing matrix (W). And the mth component of the demixing matrix (W) that optimizes [Equation 1] can be repeatedly estimated to converge using [Equation 1-4] as shown below.

[Equation 1-4]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the noise signal, is a parameter that controls the degree of constraint of the null condition, is the direction vector (H), is the demixing matrix (W), may be the mth component of the demixing matrix (W).

[Equation 2]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, is the cost function of independent component analysis, and are the Lagrangian multipliers to prevent distortion and ensure null conditions, respectively; and are the first and m components of the demixing matrix (W), may be a direction vector (H). And the first component of the demixing matrix (W) that optimizes [Equation 2] The convergence can be estimated repeatedly using [Equation 2-1] below.

[Equation 2-1]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the target signal, is the direction vector (H), May be the first component of the demixing matrix (W). And the mth component of the demixing matrix (W) that optimizes [Equation 2] can be repeatedly estimated to converge using [Equation 2-2] as shown below.

[Equation 2-2]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the noise signal, is the direction vector (H), is the demixing matrix (W), may be the mth component of the demixing matrix (W).

[Equation 3]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, is the cost function of independent component analysis, is the Lagrangian multiplier to ensure the anti-distortion condition, and are the first and m components of the demixing matrix (W), is the direction vector (H), may be a parameter that controls the degree of constraint of the null condition. And the first component of the demixing matrix (W) that optimizes [Equation 3] Can be repeatedly estimated to converge using [Equation 3-1] below.

[Equation 3-1]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the target signal, is the direction vector (H), May be the first component of the demixing matrix (W). And the mth component of the demixing matrix (W) that optimizes [Equation 3] can be repeatedly estimated to converge using [Equation 3-2] as shown below.

[Equation 3-2]

Here, k is a natural number representing the frequency index, is the Weighted Spatial Covariance Matrix (WSCM) for the noise signal, is a parameter that controls the degree of constraint of the null condition, is the direction vector (H), is the demixing matrix (W), may be the mth component of the demixing matrix (W).

In each equation, as expressed in [Equation 1], [Equation 2], and [Equation 3], By applying the constraints placed later to the cost function, the first channel (component) of the matrix including the result signal (RS) provided based on the demixing matrix (W) is fixed as the result for the target signal (TS) This can be done, and distortion of the target signal (TS) can also be reduced. Additionally, the parameters in [Equation 1] [Equation 3] is composed by combining [Equation 1] and [Equation 2] in a hybrid form to reduce distortion of speech that may occur due to a square term with a limited degree of distortion prevention condition controlled by It may be. In one embodiment, the first component of the result matrix generated based on the input signal (XS) of the microphones and the demixing matrix (W) may correspond to the target signal (TS). Here, [Equation 1], [Equation 2], and [Equation 3] is [Equation 1-2] may be the same as

In one embodiment, the product of the first component (W1) included in the demixing matrix (W) and the direction vector (H) included in the spatial transfer function (A) is 1, and the product of the first component (W1) included in the demixing matrix (W) is 1. The product of the remaining components (Wm) excluding the first component (W1) and the direction vector (H) may be 0. This content can be expressed as [Equation 4] below.

[Equation 4]

,

,

here, is the result signal (RS) corresponding to the target signal (TS), is the result signal (RS) corresponding to the noise signal (NS), may be the input signal (XS) of the microphones.

The result providing unit 300 may extract the result signal (RS) from the input signal (XS) of the microphones based on the demixing matrix (W). For example, when optimizing the cost function through Independent Component Analysis (ICA), it is divided into the result signal (RS) for the target signal (TS) and the result signal (RS) for the noise signal (NS). can be provided.

In one embodiment, the result signal (RS) for the target signal (TS) may follow a Laplacian distribution with variance that varies with time. For example, the result signal (RS) corresponding to the target signal (TS) distributed according to the Laplacian function can be modeled as shown in [Equation 5] below.

[Equation 5]

,

here, is the probability density function of the output signal (RS) for the target signal (TS), is the time-varying variance of the target signal (TS), may be a result signal (RS). Weighted spatial covariance matrix for the target of [Equation 1-2] through the signal modeled by [Equation 5] is calculated as shown in [Equation 5-1] below.

[Equation 5-1]

Here, k is a natural number representing the frequency index, is the total number of frames, is the Weighted Spatial Covariance Matrix (WSCM) for the target signal (TS), is the weight function, is a predetermined mask, and may represent the input signal (XS) of the microphones. The weight function from the target signal (TS) modeled to follow this Laplacian distribution is the result signal (RS). with a predetermined mask The time-varying variance estimated from It can be calculated by reflecting all. And the noise signal (NS) can be modeled as shown in [Equation 5-2] below.

[Equation 5-2]

here, is the probability density function of the output signal for the noise signal (NS), may be an output signal for the noise signal (NS). Accordingly, the weighted spatial covariance matrix for noise in [Equation 1-2] is calculated as in [Equation 5-3] below.

[Equation 5-3]

Here, k is a natural number representing the frequency index, is the total number of frames, is the Weighted Spatial Covariance Matrix (WSCM) for the noise signal (NS), is the weight function for the noise signal (NS), may represent the input signal (XS) of the microphones.

In one embodiment, the direction vector (H) is a spatial covariance matrix (ISCM) for the input signal (XS) of the microphones and a spatial covariance matrix (Noise Spatial Covariance Matrix) for the noise signal (NS). NSCM) can be determined depending on the difference. In another embodiment, the spatial covariance matrix (NSCM) for the noise signal (NS) is determined according to the ratio of the value corresponding to the target signal (TS) and the value corresponding to the noise signal (NS) among the result signal (RS). can be decided. For example, the method of estimating the direction vector (H) can be expressed as [Equation 6] below.

[Equation 6]

,

,

,

,

here, is the spatial covariance matrix (ISCM) for the input signals (XS) of the microphones), is the spatial covariance matrix (TSCM) for the target signal (TS), is the spatial covariance matrix (NSCM) for the noise signal (NS), may be a ratio representing the contribution of the noise component among the input components. And in direction vector estimation Can be replaced by multiplying the input signal (XS) of the microphones by the square root value of the fixed external mask as shown in [Equation 6-1] below.

[Equation 6-1]

Spatial covariance matrix for these target signals (TS) The direction vector can be estimated by extracting the main Eisen vector from .

FIGS. 4 and 5 are diagrams for explaining the online operation of the beamforming and direction vector estimation system of FIG. 1, and FIG. 6 is a diagram for explaining an embodiment of the beamforming and direction vector estimation system of FIG. 1.

Referring to FIGS. 1 to 6, the beamforming and direction vector estimation system 10 according to the present invention may operate online. In this case, the beamforming and direction vector estimation system 10 can update the demixing matrix (W) for each frame corresponding to a certain time interval. For example, the plurality of times may include a first time (T1) to a fourth time (T4), and the plurality of time intervals may include a first frame interval (FI1) to a third frame interval (FI3). You can. The first frame interval (FI1) may be a time interval from the first time (T1) to the second time (T2), and the second frame interval (FI2) may be a time interval from the second time (T2) to the third time (T3). It may be a time interval up to. Additionally, the third frame interval FI3 may be a time interval from the third time T3 to the fourth time T4. In this case, the beamforming and direction vector estimation system 10 according to the present invention updates the demixing matrix (W) during the first frame interval (FI1) and updates the demixing matrix (W) again during the second frame time interval. It can be updated. Here, as shown in FIG. 5, when the weight (WT) is gradually increased and applied to the most recent frame in the process of updating the demixing matrix (W), the performance of the beamforming and direction vector estimation system 10 can be improved. You can. In this case, the result signal (RS) can be extracted from the input signal (XS) of the microphones based on the demixing matrix during the t frame interval as shown in [Equation 7] below.

[Equation 7]

here, is the result signal (RS) corresponding to the target signal (TS) of the t-frame interval estimated through the demixing matrix (W) estimated during the t-1 frame interval, is the first channel (component) of the demixing matrix estimated for the t-1 frame interval, may be the input signal (XS) of the microphones.

In one embodiment, in order to estimate the demixing matrix (W) at the t frame interval, [Equation 1-2] corresponding to the cost function of Independent Component Analysis (ICA) is used. is defined in the tth frame of [Equation 8] below. can be replaced with

[Equation 8]

where k and m are natural numbers representing the frequency and channel index, and are the first and m components of the demixing matrix (W) estimated in the t frame, is the demixing matrix (W) estimated at the tth frame, and is the Weighted Spatial Covariance Matrix (WSCM) in the t-th frame, which is determined according to modeling of the target signal (TS) and noise signal (RS), respectively. is the forgetting factor, may represent the input signal (XS) of the microphones. This weighted spatial covariance matrix can be recursively updated online as shown in [Equation 8-1] below.

[Equation 8-1]

Here, k is a natural number representing the frequency index, and is the Weighted Spatial Covariance Matrix (WSCM) estimated at the t-th and t-1th frames, respectively; is the forgetting factor, is the weight function, may be the input signal (XS) of the microphones. And the inverse matrix of the Weighted Spatial Covariance Matrix (WSCM) at the tth frame is When expressed as [Equation 8-2] below, the update of the inverse matrix can be performed recursively immediately.

[Equation 8-2]

here, and is the inverse matrix of the Weighted Spatial Covariance Matrix (WSCM) estimated in the t-th and t-1th frames, respectively, is the forgetting factor, is the weight function, may be the input signal (XS) of the microphones. And, the result signal (RS) for the target signal (TS) and the noise signal (NS) may follow the Laplacian distribution as shown in [Equation 5] and [Equation 5-2], respectively. In order to update the result signal (RS) corresponding to the target signal (TS) distributed according to the Laplacian function of [Equation 5] online, instead of the existing [Equation 5-1] and [Equation 5-3] It can be updated online as shown in [Equation 8-3] below.

[Equation 8-3]

here, and is a weight function for the target signal (TS) and noise signal (NS), respectively, is the time-varying variance of the target signal (TS), is the smoothing factor, is a predetermined mask, is the representative value of the input signal (XS) of the microphones, is the result signal (RS) of the frame corresponding to the t-th target signal (TS) using the demixing matrix (W) estimated in the t-1-th frame, may be the result signal (RS) of the frame corresponding to the t-th noise signal (NS) using the demixing matrix (W) estimated from the t-1-th frame.

In one embodiment, in order to perform an online update, the existing [Equation 1], [Equation 2], and [Equation 3] are respectively [Equation 9], [Equation 10], and [Equation 10] below. 11].

[Equation 9]

here, is the cost function in the tth frame, k and m are natural numbers representing the frequency and channel index, respectively, is t times?? Cost function of independent component analysis in the frame, and are parameters that control the degree of restriction of distortion prevention and null conditions, respectively, and are the first and m components of the demixing matrix (W) in the t frame, may be the direction vector (H) estimated in the t-th frame. And the first component of the demixing matrix (W) that optimizes [Equation 9] can be updated by [Equation 9-1] below.

[Equation 9-1]

Here, k is a natural number representing the frequency index, and is the Weighted Spatial Covariance Matrix (WSCM) and its corresponding inverse matrix in the t frame for the target signal, is a parameter that controls the degree of constraint of the distortion prevention condition, is the direction vector (H) in the tth frame, May be the first component of the demixing matrix (W) in the t-th frame. And the m component of the demixing matrix (W) that optimizes [Equation 9] can be updated by [Equation 9-2] as follows.

[Equation 9-2]

Here, k is a natural number representing the frequency index, and is the Weighted Spatial Covariance Matrix (WSCM) and its corresponding inverse matrix in the t frame for the noise signal, is a parameter that controls the degree of constraint of the null condition, is the direction vector (H) in the tth frame, may be the mth component of the demixing matrix (W) in the tth frame.

[Equation 10]

here, is the cost function in the tth frame, k and m are natural numbers representing the frequency and channel index, respectively, is the cost function of independent component analysis in the tth frame, and is a Lagrangian multiplier to prevent distortion and ensure a null condition, respectively, in the tth frame, and are the first and m components of the demixing matrix (W) in the t frame, may be the direction vector (H) estimated in the t-th frame. And the first component of the demixing matrix (W) that optimizes [Equation 10] can be updated by [Equation 10-1] below.

[Equation 10-1]

Here, k is a natural number representing the frequency index, is the inverse matrix of the Weighted Spatial Covariance Matrix (WSCM) in the t frame for the target signal, is the direction vector (H) in the tth frame, May be the first component of the demixing matrix (W) in the t-th frame. And the m component of the demixing matrix (W) that optimizes [Equation 10] can be updated by [Equation 10-2] as follows.

[Equation 10-2]

Here, k is a natural number representing the frequency index, and is the Weighted Spatial Covariance Matrix (WSCM) and its corresponding inverse matrix in the t frame for the noise signal, is the direction vector (H) in the tth frame, may be the mth component of the demixing matrix (W) in the tth frame.

[Equation 11]

here, is the cost function in the tth frame, k and m are natural numbers representing the frequency and channel index, respectively, is t times?? Cost function of independent component analysis in the frame, is the Lagrangian multiplier to ensure the anti-distortion condition in the t frame, is a parameter that controls the degree of constraint of the null condition, and are the first and m components of the demixing matrix (W) in the t frame, may be the direction vector (H) estimated in the t-th frame. And the first component of the demixing matrix (W) that optimizes [Equation 11] can be updated by [Equation 11-1] as follows.

[Equation 11-1]

Here, k is a natural number representing the frequency index, is the inverse matrix of the Weighted Spatial Covariance Matrix (WSCM) in the t frame for the target signal, is the direction vector (H) in the tth frame, May be the first component of the demixing matrix (W) in the t-th frame. And the m component of the demixing matrix (W) that optimizes [Equation 11] can be updated by [Equation 11-2] as follows.

[Equation 11-2]

Here, k is a natural number representing the frequency index, and is the Weighted Spatial Covariance Matrix (WSCM) and its corresponding inverse matrix in the t frame for the noise signal, is a parameter that controls the degree of constraint of the null condition, is the direction vector (H) in the tth frame, may be the mth component of the demixing matrix (W) in the tth frame.

In each equation, as expressed in [Equation 9], [Equation 10], and [Equation 11], By applying the constraints placed later to the cost function, the first channel (component) of the matrix including the result signal (RS) provided based on the demixing matrix (W) updated online every frame is converted to the target signal (TS). ) can be fixed as a result, and distortion of the target signal (TS) can also be reduced. Additionally, the parameters in [Equation 1] [Equation 11] is composed by combining [Equation 9] and [Equation 10] in a hybrid form to reduce the distortion of speech that may occur due to the square term with a limited degree of distortion prevention condition controlled by It could be. In one embodiment, the first component of the result matrix generated based on the input signal (XS) of the microphones and the demixing matrix (W) updated online every frame may correspond to the target signal (TS). Here, [Equation 9], [Equation 10], and [Equation 11] of [Equation 8] It may be the same as

In one embodiment, the direction vector (H) is the spatial covariance matrix (ISCM) for the input signal (XS) of the microphones and the spatial covariance matrix (ISCM) for the noise signal (NS) calculated online every frame. It can be determined according to the difference in the matrix (Noise Spatial Covariance Matrix, NSCM). In another embodiment, the spatial covariance matrix (NSCM) for the noise signal (NS) is determined according to the ratio of the value corresponding to the target signal (TS) and the value corresponding to the noise signal (NS) among the result signal (RS). It can be decided every frame. For example, the method of estimating the direction vector (H) can be expressed as [Equation 12] below.

[Equation 12]

Here, k and m are natural numbers representing the frequency and channel index, respectively, is the mth component of the demixing matrix (W) estimated in the tth frame, is the inverse matrix of the demixing matrix (W) in the tth frame, is the ratio representing the contribution of the noise component among the input components, is the forgetting factor, is the input signal of the microphones (XS), is the spatial covariance matrix (ISCM) in the t frame for the input signals (XS) of the microphones), is the spatial covariance matrix (NSCM) in the t frame for the noise signal (NS), is a scaling factor with a real value between 0 and 1, may be the spatial covariance matrix (TSCM) in the t-th frame for the target signal (TS). And in direction vector estimation can be replaced by multiplying the input signal (XS) of the microphones by the square root value of the fixed external mask, as shown in [Equation 12-1] below.

[Equation 12-1]

Spatial covariance matrix for these target signals (TS) By extracting the main Eisen vector from , the direction vector can be estimated online for each section frame.

In one embodiment, a predetermined mask can be estimated for each frame based on diffusion as shown in [Equation 13] below.

[Equation 13]

here, and are parameters that control bias and slope, respectively, is a pair of input signals (XS) of random microphones and The diffusivity value obtained for It may be the middle value of . In another embodiment, a predetermined mask may be a value resulting from the output of a pre-trained neural network.

In one embodiment, one target point (TP) and target signal (TS) of the demixing providing unit 200 and the result providing unit 300 as shown in [Equation 4] are as shown in [Equation 14] below. Likewise, it can be expanded to multiple target points (TP) and target signals (TS). For example, if there are a total of N target signals,

[Equation 14]

here, are N result signals (RS) corresponding to N target signals (TS), is the result signal (RS) corresponding to the noise signal (NS), may be the input signal (XS) of the microphones. And the cost function expressed by [Equation 1], [Equation 2], and [Equation 3] can be extended to the case of multiple target points (TP) and target signals (TS). For example, assuming that there are a total of N target signals, the cost function corresponding to [Equation 3] can be expanded to [Equation 15] below.

[Equation 15]

here, is the cost function, k is a natural number representing the frequency index, is the cost function of independent component analysis, is a Lagrangian multiplier to ensure the distortion prevention condition of the nth target signal (TS) is the m component of the demixing matrix (W), is the direction vector (H) corresponding to the nth target signal (TS), is a parameter that controls the degree of constraint of the null condition, is the demixing matrix (W), and may be a Weighted Spatial Covariance Matrix (WSCM) determined according to modeling of the mth target signal and noise signal, respectively.

In one embodiment, the plurality of direction vectors (H) corresponding to the plurality of target signals (TS) are the spatial covariance matrix (ISCM) for the input signals (XS) of the microphones and the noise signal ( It can be determined according to the difference of the spatial covariance matrix (NSCM) for NS). In another embodiment, the spatial covariance matrix (NSCM) for the noise signal (NS) is determined according to the ratio of the value corresponding to the target signal (TS) and the value corresponding to the noise signal (NS) among the result signal (RS). can be decided. For example, when there are a total of N target signals, the method for estimating a plurality of direction vectors (H) is [Equation 6], and the corresponding estimation method can be expanded as in [Equation 16] below. .

[Equation 16]

,

here, is the spatial covariance matrix (ISCM) for the input signals (XS) of the microphones), is the spatial covariance matrix (TSCM) for the mth target signal (TS), is the spatial covariance matrix (NSCM) for the noise signal (NS), is the spatial covariance matrix (NSCM) for the remaining signals excluding the mth target signal (TS), may be a ratio representing the contribution of the remaining components excluding the mth target signal (TS) among the input components. Spatial covariance matrix for these target signals (TS) N direction vectors can be estimated by extracting the main Eisen vectors from .

In one embodiment, the demixing matrix (W) of one or a plurality of target points (TP) and target signals (TS) of the demixing provider 200 and the result provider 300 is calculated using the demixing matrix (W) of the microphones in a single frame. Rather than multiplying with the input signal (XS), it can be expanded to an operation through convolution with the input signals (XS) of microphones in multiple frames as shown in [Equation 16] below.

[Equation 17]

here, is a plurality of result signals (RS) corresponding to a plurality of target signals (TS), is the result signal (RS) corresponding to the noise signal (NS), is the convolutional demixing matrix (W), may be the input signal (XS) of the microphones, and D and L may be natural numbers representing the length of the frame delay and convolution filter. Through this expansion to a convolutional filter, the target signal can be effectively separated by using the L frames before the D frame together. And the cost function expressed in [Equation 15] can be extended to the case of the convolution demixing matrix (W). For example, the cost function corresponding to [Equation 15] can be expanded to [Equation 18] below.

[Equation 18]

here, is the cost function, k is a natural number representing the frequency index, is the cost function of independent component analysis, is a Lagrangian multiplier to ensure the distortion prevention condition of the nth target signal (TS) is the m component of the demixing matrix (W), is the direction vector (H) corresponding to the nth target signal (TS), is a parameter that controls the degree of constraint of the null condition, is the convolutional demixing matrix (W), and may be a Weighted Spatial Covariance Matrix (WSCM) determined according to modeling of the mth target signal and noise signal, respectively.

In one embodiment, the beamforming and direction vector estimation system 10 according to an embodiment of the present invention includes an input provider 100, a demixing provider 200, a result provider 300, and a voice provider ( 400). The input provider 100 may provide input signals (XS) from microphones based on a spatial transfer function (A) corresponding to the target signal (TS) and noise signal (NS) at the target point (TS). The demixing provider 200 may provide a demixing matrix (W) determined according to input signals (XS) of microphones and independent component analysis (ICA). The result providing unit 300 may extract the result signal (RS) from the input signal (XS) of the microphones based on the demixing matrix (W). The voice provider 400 may provide the result signal (RS) as a voice (SO).

FIG. 7 is a diagram illustrating an operation method of the beamforming and direction vector estimation system according to embodiments of the present invention, and FIG. 8 is a diagram illustrating an embodiment of the operation method of the beamforming and direction vector estimation system of FIG. 7. It is a drawing.

Referring to FIGS. 1 to 8, in the operating method of the beamforming and direction vector estimation system 10 according to an embodiment of the present invention, the input provider 100 provides a target signal (TS) and a target signal (TS) at the target point (TS). The input signals (XS) of the microphones can be provided based on the spatial transfer function (A) corresponding to each of the noise signals (NS) (S100). The demixing provider 200 may provide a demixing matrix (W) determined according to input signals (XS) of microphones and independent component analysis (ICA) (S200). The result providing unit 300 may extract the result signal (RS) from the input signal (XS) of the microphones based on the demixing matrix (W) (S300). The voice provider 400 may provide the result signal (RS) as a voice (SO) (S400). In the beamforming and direction vector estimation system 10 according to the present invention, the target signal (TS) generated from the target point (TS) is calculated by calculating the demixing matrix (W) using a cost function including a plurality of spatial constraints. ) can be extracted without distortion.

In addition to the technical problems of the present invention mentioned above, other features and advantages of the present invention are described below, or can be clearly understood by those skilled in the art from such description and description.

10: Beamforming and direction vector estimation system 100: Input provision unit
200: Demixing provision unit 300: Result provision unit

Claims (20)

an input providing unit that provides input signals from microphones based on a spatial transfer function corresponding to the target signal and noise signal at the target point;
a demixing provider that provides a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA); and
A beamforming and direction vector estimation system including a result providing unit that extracts result signals from input signals of the microphones based on the demixing matrix. According to paragraph 1,
The spatial transfer function includes a direction vector corresponding to a transfer function from the target point to the input provider and a noise transfer function corresponding to a transfer function until the noise signal is transmitted to the input provider. Beamforming and direction vector estimation system. According to paragraph 2,
The product of the first component included in the demixing matrix and the direction vector included in the spatial transfer function is 1, and the product of the direction vector and the remaining components excluding the first component included in the demixing matrix is 0. Beamforming and direction vector estimation system. According to paragraph 3,
Beamforming and direction vector estimation system, wherein the demixing matrix is determined based on the independent component analysis and a cost function (CF) according to space constraints. According to paragraph 4,
A beamforming and direction vector estimation system, wherein a first component of a result matrix generated based on the input signals of the microphones and the demixing matrix corresponds to the target signal. According to clause 5,
The cost function is expressed as [Equation 1],
[Equation 1]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, respectively, is the cost function of independent component analysis, and are parameters that control the degree of restriction of distortion prevention and null conditions, respectively. and are the first and m components of the demixing matrix, Beamforming and direction vector estimation system, characterized in that is a direction vector. According to clause 5,
The cost function is expressed as [Equation 2],
[Equation 2]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, is the cost function of independent component analysis, and are the Lagrangian multipliers to prevent distortion and ensure null conditions, respectively; and are the first and m components of the demixing matrix, Beamforming and direction vector estimation system, characterized in that is a direction vector. According to clause 5,
The cost function is expressed as [Equation 3],
[Equation 3]

here, is the cost function, k and m are natural numbers representing the frequency and channel index, is the cost function of independent component analysis, is the Lagrangian multiplier to ensure the anti-distortion condition, and are the first and m components of the demixing matrix, is the direction vector (H), is a beamforming and direction vector estimation system characterized in that is a parameter that controls the degree of constraint of the null condition. According to clauses 6, 7 and 8,
Cost function of the above independent component analysis is expressed as [Equation 1-2],
[Equation 1-2]

where k and m are natural numbers representing the frequency and channel index, and are the first and m components of the demixing matrix (W), is the demixing matrix (W), and is a weighted spatial covariance matrix (WSCM) determined according to modeling of the target signal and the noise signal, respectively. Beamforming and direction vector estimation system. According to paragraph 4,
A beamforming and direction vector estimation system, wherein the first to N components of the result matrix generated based on the input signals of the microphones and the demixing matrix are expanded to correspond to the N plurality of target signals. According to clause 10,
The cost function is expressed as [Equation 15],
[Equation 15]


here, is the cost function, k is a natural number representing the frequency index, is the cost function of independent component analysis, is a Lagrangian multiplier to ensure the distortion prevention condition of the nth target signal (TS) is the m component of the demixing matrix (W), is the direction vector (H) corresponding to the nth target signal (TS), is a parameter that controls the degree of constraint of the null condition, is the demixing matrix (W), and A beamforming direction vector estimation system characterized in that is a Weighted Spatial Covariance Matrix (WSCM) determined according to modeling of the target signal and the noise signal, respectively. According to clauses 9 and 11,
A beamforming and direction vector estimation system, wherein the resultant signal for the target signal follows a Laplacian distribution with variance that varies with time. According to clause 12,
The calculation formula of the Weighted Spatial Covariance Matrix (WSCM) and weight function for the target signal (TS) through the Laplacian distribution with variance varying with time is expressed as [Equation 5-1],
[Equation 5-1]



Here, k is a natural number representing the frequency index, is the total number of frames, is the Weighted Spatial Covariance Matrix (WSCM) for the target signal (TS), is the weight function, is a predetermined mask, and Beamforming and direction vector estimation system characterized in that is the input signal of the microphones (XS) and the representative value of the input signal of the microphones (XS) According to clauses 6, 7, 8 and 11,
The direction vector is characterized in that it is determined according to the difference between the spatial covariance matrix (Input Spatial Covariance Matrix, ISCM) for the input signal of the microphones and the spatial covariance matrix (Noise Spatial Covariance Matrix, NSCM) for the noise signal. Beamforming and direction vector estimation system. According to clause 14,
A beamforming and direction vector estimation system, wherein the spatial covariance matrix for the noise signal is determined according to the ratio of a value corresponding to the target signal and a value corresponding to the noise signal among the result signals. In clauses 4 and 5,
The beamforming and direction vector estimation system is operated for each frame corresponding to a constant time interval to update the demixing matrix online. According to clause 13,
predetermined mask is a beamforming and direction vector estimation system that can be estimated every frame based on diffusivity. an input providing unit that provides input signals from microphones based on spatial transfer functions corresponding to each of the target signal and noise signal at the target point;
a demixing provider that provides a demixing matrix determined according to the input signals of the microphones, independent component analysis (ICA), and spatial constraints;
a result providing unit that extracts a result signal from the input signals of the microphones based on the demixing matrix; and
A beamforming and direction vector estimation system including a voice provider that provides the result signal as a voice. An input providing unit providing input signals from microphones based on spatial transfer functions corresponding to each of the target signal and noise signal at the target point;
A demixing provider providing a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA) subject to space constraints; and
A method of operating a beamforming and direction vector estimation system including the step of a result providing unit extracting a result signal from input signals of the microphones based on the demixing matrix. An input providing unit providing input signals from microphones based on spatial transfer functions corresponding to each of the target signal and noise signal at the target point;
A demixing provider providing a demixing matrix determined according to the input signals of the microphones and independent component analysis (ICA) subject to space constraints;
A result providing unit extracting a result signal from the input signal of the microphones based on the demixing matrix; and
A method of operating a beamforming and direction vector estimation system comprising the step of a voice providing unit providing the result signal as a voice.