Problem

How should I adjust its parameters when sound source separation is suboptimal?

Solution

This section describes the settings for GHDSS , the primary module for sound source separation.

**Settings dependent on pre-measured spatial transfer function**

Since GHDSS separates using information on spatial transfer functions measured beforehand or calculated from microphone positions, its settings must be in accordance with those of the transfer functions concerned. Concretely, they correspond to the following set values.

`LC_CONST = FULL`

When transfer functions are measured properly, set this to`FULL`. Otherwise,`DIAG`.

**Determination of the curvature of non-linear constraints**

In GHDSS , the coefficient `SS_SCAL`, corresponding to the curvature (gradient at the origin) of a sigmoidal function, determines the performance. Increasing this curvature brings it closer to the linear constraint, whereas decreasing this curvature increases its non-linearity. Since too low a setting would result in a dull adaptation, its value should depend on the target environment.

**Initial separation matrix**

You can specify the initial separation matrix by setting `INITW_FILENAME`. An appropriate initial separation matrix reduces the convergence time for the separation. If you do not specify a file name, the initial matrix is constructed by the transfer function file and the localization result from LocalizeMUSIC .

**Step size calculation method**

There are two types of step size calculation methods, `SS_METHOD` for higher-order decorrelation, and `LC_METHOD` for geometric constraints. The performance of both is improved by setting them to ** ADAPTIVE** , unless the environment has been highly optimized. If you set

**Step size calculation method for higher-order decorrelation :**`SS_METHOD`

**1. FIX**

If `SS_METHOD` is set at `FIX`, `SS_MYU` will appear in the property window. You can input a value, e.g., 0.001, in `SS_MYU`. A larger value reduces convergence time, while decreasing stability and accuracy. In contrast, a smaller value improves convergence stability and accuracy, while decreasing convergence time.

**2. ADAPTIVE**

If `SS_METHOD` is set as `ADAPTIVE`, the step size will be automatically optimized, improving the stability and accuracy of convergence.

**3. LC_MYU**

In this case, step size is defined by the `LC_METHOD`.

**Step size calculation method for geometric constraints :**`LC_METHOD`

**1. FIX**

If you set `LC_METHOD` as `FIX`, you can see `LC_MYU`. The description is the same as that for `SS_METHOD`.

**2. ADAPTIVE**

If `LC_METHOD` is set to `ADAPTIVE`, the step size will be automatically optimized.

Discussion

See above description of solution

See Also

For details of the algorithms for sound source separation, see “Technical description of HARK (sound source separation)” in the HARK training session material.