  Linear operations on coefficients in the spherical harmonics (SH) transform
domain which again yield SH-domain coefficients are an important toolset in
many disciplines of research and engineering. They comprise rotations,
spatially selective filters, and many other modifications for various
applications, or describe a MIMO system's response to an excitation. It is of
particular importance to characterize these operations both qualitatively and
quantitatively, and make them accessible for people to work with. In this
paper, we identify different key properties of such operations and propose a
method for their visualization. With our proposed method, we succeed to show
many important aspects of an operation in a single plot and give rise to a
comprehensive interpretation of a system's behavior. In our evaluation, we show
the potential of the proposed method on the basis of various practical examples
from spatial audio signal processing, where SH-domain filtering is used to
modify acoustic scenes given by higher-order Ambisonics signals.
