  Using a 3D global solver of the linearized Euler equations, we model acoustic
oscillations over background velocity flow fields of single-cell meridional
circulation with deep and shallow return flows as well as a double-cell
meridional circulation profile. The velocities are generated using a mean-field
hydrodynamic and dynamo model -- moving through the regimes with minimal
parameter changes; counter-rotation near the base of the tachocline is induced
by sign inversion of the non-diffusive action of turbulent Reynolds stresses
($\Lambda$-effect) due to the radial inhomogeneity of the Coriolis number. By
mimicking the stochastic excitation of resonant modes in the convective
interior, we simulate realization noise present in solar observations. Using
deep-focusing to analyze differences in travel-time signatures between the
three regimes, as well as comparing to solar observations, we show that current
helioseismology techniques may offer important insights about the location of
the return flow, however, that it may not be possible to definitively
distinguish between profiles of single-cell or double-cell meridional
circulation.
