Apply focus to a first order ambisonic signal (B-format) along an arbitrary axis.
The B-format signal, an array: [w, x, y, z]
The distortion angle, in radians. -pi/2 to pi/2
Azimuth, in radians.
Elevation, in radians.
Output will be multiplied by this value.
This value will be added to the output.
Applies focus along the axis defined by theta and phi. See FoaFocusX.
Please see various examples here.