Top: significance of single-field models for the potential feature case with a K² cos ωK scaling dependence (Eq. (16)). Bottom: significance for rapidly varying sound speed with a K sin ωK scaling (Eq. (17)). Left panels: for T only and right panels: for T + E. These results have been marginalized over the envelope parameter α (determined by feature width and height) from α = 0 to αω = 90. There appears to be no evidence for these very specific signatures in this frequency range when polarization data are included.