  Linear operations on coefficients in the spherical harmonics (SH) transform
domain that 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 the response of a MIMO system 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 the behavior of a system. 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.
