Fig. 4

Call source levels under different light and noise treatments. (A) Scatterplot of the change in source levels by noise condition, where ΔSL is the change in SL with respect to the mean SL (at ranges 2–4 m) per bat in silent controls. (B) Probability histograms of call source levels for all light and noise combinations, showing the Lombard response shift of SL in noise treatments (also shown in A). (C) Magnitude of the logarithmic SL compensation with range, shown as the slope of the linear regression of SL versus log₁₀(range). Boxplots are based on individual means (n = 5 bats, grey points) and are spaced in logarithmic range bins