6.3.2 BeamForming

6.3.2.1 Outline of the node

BeamForming node performs sound source separation based on the following methods:

Node inputs are:

Note outputs are a set of complex spectrum of each separated sound.

6.3.2.2 Necessary files

Table 6.38: Necessary files for BeamForming 

Corresponding parameter name

Description

TF_CONJ_FILENAME

Transfer function of microphone array

6.3.2.3 Usage

When to use

This node is used to perform sound source separation on the sound source direction originated using a microphone array. As a sound source direction, either a value estimated by sound source localization or a constant value may be used.

Typical connection

Figure 6.52 shows connection examples of the BeamForming . The node has three inputs as follows:

  1. INPUT_FRAMES takes a multi-channel complex spectrum containing the mixture of sounds produced by for example MultiFFT ,

  2. INPUT_SOURCES takes the results of sound source localization produced by for example LocalizeMUSIC or ConstantLocalization ,

  3. INPUT_NOISE_SOURCES takes the results of sound source localization for noise sources produced by for example LocalizeMUSIC or ConstantLocalization .

The output is the separated signals.

\includegraphics[width=.8\textwidth ]{fig/modules/Beamforming.eps}
Figure 6.52: Example of Connections of BeamForming 

6.3.2.4 Input-output and property of the node

Input

INPUT_FRAMES

: Matrix<complex<float> >  type. Multi-channel complex spectra. Corresponding to the complex spectrum of input waveform from each microphone, the rows correspond to the channels and the columns correspond to the frequency bins.

INPUT_SOURCES

: Vector<ObjectRef>  type. A Vector array of the Source type object in which sound source localization results are stored. Typically, takes the output of SourceIntervalExtender connected to SourceTracker .

INPUT_NOISE_SOURCES

: Vector<ObjectRef>  type. A Vector array of the Source type object where noise source localization results are stored. The input is optional. It enables to avoid lowering performance of beamforming due to noise.

Output

OUTPUT

: Map<int, ObjectRef>  type. A pair containing the sound source ID and the complex spectrum of the separated sound (Vector<complex<float> >  type). Output as many as the number of sound sources .

Parameter

LENGTH

: int  type. Analysis frame length [samples], which must be equal to the values at a preceding node (e.g. AudioStreamFromMic or the MultiFFT ). The default is 512.

ADVANCE

: int  type. Shift length of a frame [samples], which must be equal to the values at a preceding node (e.g. AudioStreamFromMic or the MultiFFT ). The default is 160.

SAMPLING_RATE

: int  type. Sampling frequency of the input waveform [Hz]. The default is 16000.

LOWER_BOUND_FREQUENCY

: int  type. This parameter is the minimum frequency used when separation processing is performed. Processing is not performed for frequencies below this value and the value of the output spectrum is zero then. The user designates a value in the range from 0 to half of the sampling frequency.

UPPER_BOUND_FREQUENCY

: int  type. This parameter is the maximum frequency used when separation processing is performed. Processing is not performed for frequencies above this value and the value of the output spectrum is zero then. LOWER_BOUND_FREQUENCY $<$ UPPER_BOUND_FREQUENCY must be maintained.

TF_CONJ_FILENAME

: string  type. The file name in which the transfer function database of your microphone array is saved. Refer to Section 5.3.1 for the detail of the file format.

INITW_FILENAME

: string  type. The file name in which the initial value of a separation matrix is described. Initializing with a converged separation matrix through preliminary computation allows for separation with good precision from the beginning. If specified, a matrix in INITW_FILENAME is used as an initial separation matrix. Otherwise, the pre-measured separation matrix obtained from a database in TF_CONJ_FILENAME or the separation matrix estimated from a geometric relation is used as an initial separation matrix.

GICA_SS_METHOD

: string  type. Select a stepsize of ICA (Independent Component Analysis) calculation method based for a blind source separation. If FIX, GICA_SS_MYU designed fix value is used. If LC_MYU, GICA_LC_MYU associated with the step size based on geometric constraint is used. If ADAPTIVE, the stepsize is adaptively determined.

GICA_SS_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on blind source separation. The default value is 0.001. If GICA_SS_METHOD = FIX, GICA_SS_MYU is the designated value for the stepsize. If GICA_SS_METHOD = LC_MYU, this parameter is ignored. If GICA_SS_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by GICA_SS_MYU, resulting the final stepsize. By setting this value and GICA_LC_MYU to zero and passing a separation matrix of delay-and-sum beamformer type as INITW_FILENAME, processing equivalent to delay-and-sum beamforming is performed.

GHDSS_SS_METHOD

: string  type. Select a stepsize calculation method based for HDSS (Higher-order Decorrelation-based Source Separation). If FIX, GHDSS_SS_MYU designed fix value is used. If LC_MYU, GHDSS_LC_MYU associated with the step size based on geometric constraint is used. If ADAPTIVE, the stepsize is adaptively determined.

GHDSS_SS_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on HDSS (Higher-order Decorrelation-based Source Separation). The default value is 0.001. If GHDSS_SS_METHOD = FIX, GHDSS_SS_MYU is the designated value for the stepsize. If GHDSS_SS_METHOD = LC_MYU, this parameter is ignored. If GHDSS_SS_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by GHDSS_SS_MYU, resulting the final stepsize. By setting this value and GHDSS_LC_MYU to zero and passing a separation matrix of delay-and-sum beamformer type as INITW_FILENAME, processing equivalent to delay-and-sum beamforming is performed.

LCMV_LC_METHOD

: string  type. Select a stepsize calculation method for separation based on linearly constraints. This parameter affects the stepsize for the source separation based on linearly constraints (LC). If FIX, LCMV_LC_MYU designed fix value is used. If ADAPTIVE, the stepsize is adaptively determined.

LCMV_LC_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on linearly constraints. The default value is 0.001. If LCMV_LC_METHOD = FIX, LCMV_LC_MYU is the designated value for the stepsize. If LCMV_LC_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by LCMV_LC_MYU, resulting the final stepsize.

GJ_LC_METHOD

: string  type. Select a stepsize calculation method for separation based on linearly constraints. If FIX, GJ_LC_MYU designed fix value is used. If ADAPTIVE, the stepsize is adaptively determined.

GJ_LC_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on linearly constraints. The default value is 0.001. If GJ_LC_METHOD = FIX, GJ_LC_MYU is the designated value for the stepsize. If GJ_LC_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by GJ_LC_MYU, resulting the final stepsize.

GICA_LC_METHOD

: string  type. Select a stepsize calculation method for separation based on geometric constraints (GC). If FIX, GICA_LC_MYU designed fix value is used. If ADAPTIVE, the stepsize is adaptively determined.

GICA_LC_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on geometric constraints. The default value is 0.001. If GICA_LC_METHOD = FIX, GICA_LC_MYU is the designated value for the stepsize. If GICA_LC_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by LCMV_LC_MYU, resulting the final stepsize. By setting this value and GICA_SS_MYU to zero and passing a separation matrix of delay-and-sum beamformer type as INITW_FILENAME, processing equivalent to delay-and-sum beamforming is performed.

GHDSS_LC_METHOD

: string  type. Select a stepsize calculation method for separation based on geometric constraints. This parameter affects the stepsize for the source separation based on geometric constraints (GC). If FIX, GHDSS_LC_MYU designed fix value is used. If ADAPTIVE, the stepsize is adaptively determined.

GHDSS_LC_MYU

: float  type. Designate the stepsize to be used when updating a separation matrix based on geometric constraints. The default value is 0.001. If GHDSS_LC_METHOD = FIX, GHDSS_LC_MYU is the designated value for the stepsize. If GHDSS_LC_METHOD = ADAPTIVE, the adaptive stepsize is multiplied by GHDSS_LC_MYU, resulting the final stepsize. By setting this value and GHDSS_SS_MYU to zero and passing a separation matrix of delay-and-sum beamformer type as INITW_FILENAME, processing equivalent to delay-and-sum beamforming is performed.

GHDSS_LC_CONST

: string  type. Select geometric constraint method. If DIAG, use only diagonal components (direct sound components) for geometric constraints. If FULL, use off-diagonal components in addition to diagonal components (direct sound components) for geometric constraints. Highly precise separation is possible even with DIAG, because the blind spot is automatically formed by higher order decorrelation.

GICA_SS_SCAL

: float  type. Designate the scale factor of a hyperbolic tangent function (tanh) in calculation of the higher-order correlation matrix. The default value is 1.0. A positive real number greater than zero must be designated. The smaller the value is, the less non-linearity, which makes the calculation close to a normal correlation matrix calculation.

GHDSS_SS_SCAL

: float  type. Designate the scale factor of a hyperbolic tangent function (tanh) in calculation of the higher-order correlation matrix. The default value is 1.0. A positive real number greater than zero must be designated. The smaller the value is, the less non-linearity, which makes the calculation close to a normal correlation matrix calculation.

GHDSS_NOISE_FLOOR

: float  type. Specify the amplitude threshold (upper limit) that regards the input signal as noise. The default value is 0. When the amplitude of the input signal is less than this value, it is regarded as a noise section and the separation matrix is not updated. Specify a positive real number, if the noise is large and the separation matrix does not converge stably.

GHDSS_UPDATE

: string  type. Decide how to update separation matrix. If STEP, update based on geometric constraints is performed after updating based on higher order decorrelation. If TOTAL, perform updates based on higher order decorrelation and update based on geometric constraints at the same time.

UPDATE_METHOD_W

: string  type. Recalculation of separation matrix is required when sound source position information changes. At this time, designate a method to consider sound source position information changed. The separating matrix is internally stored together with the coordinates of the sound source ID and the sound source direction for a certain period of time, and once the sound is stopped, if a sound judged to be a sound source from the same direction is detected, the separating matrix saved again The separation process is performed. At this time, a criterion as to whether or not to update the separation matrix is set. If ID, it is judged by the sound source ID whether it is the same direction sound source or not. If POS, it is judged by comparing the coordinates of the sound source direction. If ID_POS, at first sound source IDs are compared, if they are not determined to be identical, further, judgment is made by comparing the coordinates of the sound source direction.

UPDATE_ACCEPT_DISTANCE

: float  type. Distance to be regarded as the same sound source for movement of the sound source [mm]. If it is within the set distance range, calculation is performed using the updated separation matrix. The default value is 300.0.

EXPORT_W

: bool  type. The user determines if the results of the separation matrix updated will be output. When true, select EXPORT_W_FILENAME.

EXPORT_W_FILENAME

: string  type. Designate the name of the file into which a separation matrix will be output. For its format, see Section 5.3.2.

BF_METHOD

: string  type. Designate the sound source separation method. Currently, this node supports the following separation methods:

  • DS : Delay-and-Sum beamforming [1]

  • WDS : Weighted Delay-and-Sum beamforming [1]

  • NULL : NULL beamforming [1]

  • ILSE : Iterative Least Squares with Enumeration [2]

  • LCMV : Linearly Constrained Minimum Variance beamforming [3]

  • GJ : Griffiths-Jim beamforming [4]

  • GICA : Geometrically constrained Independent Component Analysis [5]

  • GHDSS : Geometrically constrained Higher-order Decorrelation-based Source Separation [5]

ENABLE_DEBUG

: bool  type. Setting the value to true outputs the separation status to the standard output. The default value is false.

Table 6.39: Parameter list of BF_METHOD = DS,WDS,NULL,ILSE

Parameter name

Type

Default value

Unit

Description

LENGTH

int 

512

[pt]

Analysis frame length.

ADVANCE

int 

160

[pt]

Shift length of frame.

SAMPLING_RATE

int 

16000

[Hz]

Sampling frequency.

LOWER_BOUND_FREQUENCY

int 

0

[Hz]

The minimum value of the frequency used for separation processing.

UPPER_BOUND_FREQUENCY

int 

8000

[Hz]

The maximum value of the frequency used for separation processing.

TF_CONJ_FILENAME

string 

   

File name of transfer function database of your microphone array.

ENABLE_DEBUG

bool 

false

 

Enabling debug output.

Table 6.40: Parameter list of BF_METHOD = LCMV

Parameter name

Type

Default value

Unit

Description

LENGTH

int 

512

[pt]

Analysis frame length.

ADVANCE

int 

160

[pt]

Shift length of frame.

SAMPLING_RATE

int 

16000

[Hz]

Sampling frequency.

LOWER_BOUND_FREQUENCY

int 

0

[Hz]

The minimum value of the frequency used for separation processing.

UPPER_BOUND_FREQUENCY

int 

8000

[Hz]

The maximum value of the frequency used for separation processing.

TF_CONJ_FILENAME

string 

   

File name of transfer function database of your microphone array.

INITW_FILENAME

string 

   

A file name in which the initial value of the separation matrix is described.

LCMV_LC_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on geometric constraints.If FIX, LCMV_LC_MYU designed fix value is used.If ADAPTIVE, the stepsize is adaptively determined.

LCMV_LC_MYU

float 

0.001

 

The stepsize when updating a separation matrix based on geometric constraints.

UPDATE_METHOD_W

string 

ID

 

How to regard sound source position information as changed.

UPDATE_ACCEPT_DISTANCE

float 

300.0

[mm]

Distance to be regarded as the same sound source with respect to movement of the sound source.

EXPORT_W

bool 

false

 

Designate whether separation matrixes are to be written to files.

EXPORT_W_FILENAME

string 

   

The name of the file to which the separation matrix is written.

ENABLE_DEBUG

bool 

false

 

Enabling debug output.

Table 6.41: Parameter list of BF_METHOD = GJ

Parameter name

Type

Default value

Unit

Description

LENGTH

int 

512

[pt]

Analysis frame length.

ADVANCE

int 

160

[pt]

Shift length of frame.

SAMPLING_RATE

int 

16000

[Hz]

Sampling frequency.

LOWER_BOUND_FREQUENCY

int 

0

[Hz]

The minimum value of the frequency used for separation processing.

UPPER_BOUND_FREQUENCY

int 

8000

[Hz]

The maximum value of the frequency used for separation processing.

TF_CONJ_FILENAME

string 

   

File name of transfer function database of your microphone array.

INITW_FILENAME

string 

   

A file name in which the initial value of the separation matrix is described.

GJ_LC_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on geometric constraints.If FIX, GJ_LC_MYU designed fix value is used.If ADAPTIVE, the stepsize is adaptively determined.

GJ_LC_MYU

float 

0.001

 

The stepsize when updating a separation matrix based on geometric constraints.

UPDATE_METHOD_W

string 

ID

 

How to regard sound source position information as changed.

UPDATE_ACCEPT_DISTANCE

float 

300.0

[mm]

Distance to be regarded as the same sound source with respect to movement of the sound source.

EXPORT_W

bool 

false

 

Designate whether separation matrixes are to be written to files.

EXPORT_W_FILENAME

string 

   

The name of the file to which the separation matrix is written.

ENABLE_DEBUG

bool 

false

 

Enabling debug output.

Table 6.42: Parameter list of BF_METHOD = GICA

Parameter name

Type

Default value

Unit

Description

LENGTH

int 

512

[pt]

Analysis frame length.

ADVANCE

int 

160

[pt]

Shift length of frame.

SAMPLING_RATE

int 

16000

[Hz]

Sampling frequency.

LOWER_BOUND_FREQUENCY

int 

0

[Hz]

The minimum value of the frequency used for separation processing.

UPPER_BOUND_FREQUENCY

int 

8000

[Hz]

The maximum value of the frequency used for separation processing.

TF_CONJ_FILENAME

string 

   

File name of transfer function database of your microphone array.

INITW_FILENAME

string 

   

A file name in which the initial value of the separation matrix is described.

GICA_SS_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on blind source separation.If FIX, GICA_SS_MYU designed fix value is used.If LC_MYU, GICA_LC_MYU associated with the step size based on geometric constraint is used.If ADAPTIVE, the stepsize is adaptively determined.

GICA_SS_MYU

float 

0.001

 

The stepsize when updating a separation matrix based on blind source separation.

GICA_LC_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on geometric constraints.If FIX, GICA_LC_MYU designed fix value is used.If ADAPTIVE, the stepsize is adaptively determined.

GICA_LC_MYU

float 

0.001

 

The stepsize when updating a separation matrix based on geometric constraints.

GICA_SS_SCAL

float 

1.0

 

The scale factor in a higher-order correlation matrix computation.

UPDATE_METHOD_W

string 

ID

 

How to regard sound source position information as changed.

UPDATE_ACCEPT_DISTANCE

float 

300.0

[mm]

Distance to be regarded as the same sound source with respect to movement of the sound source.

EXPORT_W

bool 

false

 

Designate whether separation matrixes are to be written to files.

EXPORT_W_FILENAME

string 

   

The name of the file to which the separation matrix is written.

ENABLE_DEBUG

bool 

false

 

Enabling debug output.

Table 6.43: Parameter list of BF_METHOD = GHDSS

Parameter name

Type

Default value

Unit

Description

LENGTH

int 

512

[pt]

Analysis frame length.

ADVANCE

int 

160

[pt]

Shift length of frame.

SAMPLING_RATE

int 

16000

[Hz]

Sampling frequency.

SPEED_OF_SOUND

float 

343.0

[m/s]

Sound speed.

TF_CONJ_FILENAME

string 

   

File name of transfer function database of your microphone array.

INITW_FILENAME

string 

   

A file name in which the initial value of the separation matrix is described.

GHDSS_SS_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on higher-order decorrelation.If FIX, GHDSS_SS_MYU designed fix value is used.If LC_MYU, GHDSS_LC_MYU associated with the step size based on geometric constraint is used.If ADAPTIVE, the stepsize is adaptively determined.

GHDSS_SS_MYU

float 

1.0

 

The stepsize when updating a separation matrix based on higher-order decorrelation.

GHDSS_LC_METHOD

string 

ADAPTIVE

 

A stepsize calculation method based on geometric constraints.If FIX, GHDSS_LC_MYU designed fix value is used.If ADAPTIVE, the stepsize is adaptively determined.

GHDSS_LC_MYU

float 

1.0

 

The stepsize when updating a separation matrix based on geometric constraints.

GHDSS_LC_CONST

string 

FULL

 

Determine geometric constraints.If DIAG, use only diagonal components.If FULL, use whole part.

GHDSS_SS_SCAL

float 

1.0

 

The scale factor in a higher-order correlation matrix computation.

GHDSS_NOISE_FLOOR

float 

0.0

 

The threshold value of the amplitude for judging the input signal as noise (upper limit).

GHDSS_UPDATE

string 

STEP

 

The method to update separation matrixes.If STEP, update based on geometric constraints is performed after updating based on higher order decorrelation.If TOTAL, perform updates at the same time.

UPDATE_METHOD_W

string 

ID

 

How to regard sound source position information as changed.

UPDATE_ACCEPT_DISTANCE

float 

300.0

[mm]

Distance to be regarded as the same sound source with respect to movement of the sound source.

EXPORT_W

bool 

false

 

Designate whether separation matrixes are to be written to files.

EXPORT_W_FILENAME

string 

   

The name of the file to which the separation matrix is written.

ENABLE_DEBUG

bool 

false

 

Enabling debug output.

6.3.2.5 Details of the node

Technical details: Basically, the technical detail of each separation method can be found in the references below.

Bried explanation of sound source separation:

Table 6.44 shows the notation of variables used in sound source separation problems. Since the source separation is performed frame-by-frame in the frequency domain, all the variable is computed in a complex field. Also, the separation is performed for all $K$ frequency bins ($1 \leq k \leq K$). Here, we omit $k$ from the notation. Let $N$, $M$, and $f$ denote the number of sound sources and the number of microphones, and the frame index, respectively.

Table 6.44: Notation of variables

Variables

Description

$\boldsymbol {S}(f) = \left[S_1(f), \dots , S_ N(f)\right]^ T$

Complex spectrum of target sound sources at the $f$-th frame

$\boldsymbol {X}(f) = \left[X_1(f), \dots , X_ M(f)\right]^ T$

Complex spectrum of a microphone observation at the $f$-th frame, which corresponds to INPUT_FRAMES.

$\boldsymbol {N}(f) = \left[N_1(f), \dots , N_ M(f)\right]^ T$

Complex spectrum of added noise

$\boldsymbol {H} = \left[ \boldsymbol {H}_1, \dots , \boldsymbol {H}_ N \right] \in \mathbb {C}^{M \times N}$

Transfer function matrix from the $n$-th sound source ($1 \leq n \leq N$) to the $m$-th microphone ($1 \leq m \leq M$)

$\boldsymbol {W}(f) = \left[ \boldsymbol {W}_1, \dots , \boldsymbol {W}_ M \right] \in \mathbb {C}^{N \times M}$

Separation matrix at the $f$-th frame

$\boldsymbol {Y}(f) = \left[Y_1(f), \dots , Y_ N(f)\right]^ T$

Complex spectrum of separated signals

We use the following linear model for the signal processing:

  $\displaystyle \boldsymbol {X}(f) $ $\displaystyle = $ $\displaystyle \boldsymbol {H}\boldsymbol {S}(f) + \boldsymbol {N}(f)~ .\label{eq:beamforming-observation} $   (38)

The purpose of the separation is to estimate $\boldsymbol {W}(f)$ based on the following equation:

  $\displaystyle \boldsymbol {Y}(f) $ $\displaystyle = $ $\displaystyle \boldsymbol {W}(f)\boldsymbol {X}(f) \label{eq:Beamforming-separation} $   (39)

so that $\boldsymbol {Y}(f)$ is getting closer to $\boldsymbol {S}(f)$. After separation, the estimated $\boldsymbol {W}(f)$ can be saved by setting EXPORT_W=true and put a certain name in EXPORT_W_FILENAME.

TF_CONJ_FILENAME specifies the transfer function matrix $\boldsymbol {H}$ which is pre-measured or pre-calculated. Hereinafter, we denote this pre-measured transfer function as $\hat{\boldsymbol {H}}$ to distinguish from $\boldsymbol {H}$.

Separation by BF_METHOD = DS,WDS,NULL,ILSE: $\boldsymbol {W}(f)$ is directly determined using $\hat{\boldsymbol {H}}$ and corresponding the directions of target recieved at the INPUT_SOURCES terminal and the directions of noise recieved at the INPUT_NOISE_SOURCES terminal.

Separation by BF_METHOD = LCMV,GJ: The cont function $J_{\textrm{L}}(\boldsymbol {W}(f))$ for updating the separation matrix is defined by the directions of target recieved at the INPUT_SOURCES terminal and the directions of noise recieved at the INPUT_NOISE_SOURCES terminal. The equation for updating the separation matrix is described simply as follows:

  $\displaystyle \boldsymbol {W}(f+1) $ $\displaystyle = $ $\displaystyle \boldsymbol {W}(f) + \mu \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{L}}(\boldsymbol {W})(f)~ ,\label{eq:LCMV-GJ-J} $   (40)

where $\nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{L}}(\boldsymbol {W}) = \frac{\partial \boldsymbol {J}_{\textrm{L}}(\boldsymbol {W})}{\partial \boldsymbol {W}}$. LC_MYU specifies the value of $\mu $. If LC_METHOD = ADAPTIVE, this node computes the adaptive stepsize based on the following equation.

  $\displaystyle \mu $ $\displaystyle = $ $\displaystyle \left. \frac{\boldsymbol {J}_{\textrm{L}}(\boldsymbol {W})}{\left| \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{L}}(\boldsymbol {W})\right|^2} \right|_{\boldsymbol {W} = \boldsymbol {W}(f)}\label{eq:LCMV-GJ-mu} $   (41)

Separation by BF_METHOD = GICA: The cont function $J_{\textrm{G}}(\boldsymbol {W}(f))$ for updating the separation matrix is defined by the directions of target recieved at the INPUT_SOURCES terminal and the directions of noise recieved at the INPUT_NOISE_SOURCES terminal.

  $\displaystyle J_{\textrm{G}}(\boldsymbol {W}(f)) $ $\displaystyle = $ $\displaystyle J_{\textrm{SS}}(\boldsymbol {W}(f)) + J_{\textrm{LC}}(\boldsymbol {W}(f))~ , \label{eq:GHDSS-J} $   (42)

where $J_{\textrm{SS}}(\boldsymbol {W}(f))$ is the cost function for the blind source separation, $J_{\textrm{LC}}(\boldsymbol {W}(f))$ is the cost function for the source separation based on geometric constraints. The equation for updating the separation matrix is described simply as follows:

  $\displaystyle \boldsymbol {W}(f+1) $ $\displaystyle = $ $\displaystyle \boldsymbol {W}(f) + \mu _{\textrm{SS}} \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{SS}}(\boldsymbol {W})(f) + \mu _{\textrm{LC}} \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{LC}}(\boldsymbol {W})(f)~ , \label{eq:GHDSS-W} $   (43)

where $\nabla _{\boldsymbol {W}}$ means the partial derivative in respect of $\boldsymbol {W}$ same as Eq. (40). The $\mu _{\textrm{SS}}$ and $\mu _{\textrm{LC}}$ in the equation can be specified by SS_MYU and LC_MYU, respectively. If SS_METHOD = ADAPTIVE, $\mu _{\textrm{SS}}$ is adaptively determined by

  $\displaystyle \mu _{\textrm{SS}} $ $\displaystyle = $ $\displaystyle \left. \frac{\boldsymbol {J}_{\textrm{SS}}(\boldsymbol {W})}{\left| \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{SS}}(\boldsymbol {W})\right|^2} \right|_{\boldsymbol {W} = \boldsymbol {W}(f)}~ .\label{eq:GHDSS-SS-mu} $   (44)

If LC_METHOD = ADAPTIVE, $\mu _{\textrm{LC}}$ is adaptively determined by

  $\displaystyle \mu _{\textrm{LC}} $ $\displaystyle = $ $\displaystyle \left. \frac{\boldsymbol {J}_{\textrm{LC}}(\boldsymbol {W})}{\left| \nabla _{\boldsymbol {W}}\boldsymbol {J}_{\textrm{LC}}(\boldsymbol {W})\right|^2} \right|_{\boldsymbol {W} = \boldsymbol {W}(f)}~ .\label{eq:GHDSS-LC-mu} $   (45)

Trouble shooting: Basically, follow the trouble shooting of the GHDSS node.

6.3.2.6 References