In the presence of Thomson scattering, the observable amplitude of a signal will be lower than the original modulation amplitude, depending on optical depth, τ, and density, n. We show estimated densities below which periodic oscillations would lead to reductions of the amplitude (and thus detectability) by 64−99%, depending on three values of optical depth τ = 5−1 that would lead to 1−37% of photons escaping unscattered; see Sect. 5.1.