  Normal modes are coupled by the presence of perturbations in the Sun,
providing a novel and under-appreciated helioseismic technique with which to
image the solar interior. The process of measuring coupling between normal
modes is straightforward, much more so when compared with other prevalent
helioseismic techniques. The theoretical framework to interpret these
measurements is well developed with the caveat that it applies only in the case
where the entire surface of the Sun is observed. In practice however, the
limited visibility of the Sun and line-of-sight related effects diminish the
resolution of the technique. Here, we compute realistic sensitivities of
normal-mode coupling measurements to flows in the solar interior and describe
how to mitigate the sometimes-overwhelming effect of leakage. The importance of
being able to isolate individual spherical harmonics and observe the full Sun,
to which future solar observatories may aspire, is thus highlighted in our
results. In the latter part of the article, we describe the noise model for the
variance of coupling coefficients, a critical component to the process of
inference.
