Empirical data (filled symbols) and model predictions (open symbols) for masked thresholds for wideband N₀S_m (upper-left panel), N₀S_π (upper-right panel), N_πS_m (middle-left panel), and N_πS₀ (middle-right panel) conditions as a function of the frequency of the signal. Differences in thresholds between the N_πS_m and N₀S_m are shown in the lower-left panel, while the lower-right panel represents differences in threshold between N_πS₀ and N₀S_π.