Adjust the soundfield directivity of a first order ambisonic signal (B-format) across an arbitrary plane.
The B-format signal, an array: [w, x, y, z]
The distortion angle, in radians. 0 to pi/2
Azimuth for the normal to the plane, in radians.
Elevation for the normal to the plane, in radians.
Output will be multiplied by this value.
This value will be added to the output.
Angle = 0 retains the current directivity of the soundfield. Increasing angle towards pi/2 decreases the directivity along the normal defined by theta and phi, reducing the gain on this normal to zero, and is equivalent to a spatial low-pass filter. The resulting image becomes directionless on the normal.
Please see various examples here.