Fig. 6
From: A novel theory of Asian elephant high-frequency squeak production
Squeak mean F0 across call (Hz) plotted against age (years). Fitted regression line (y = 895.8–2.670x) for 13 females (black symbols) (Ncalls = 225, Ncall/subject = 4–30, χ2 = 0.419, df = 4, P value = 0.51, Table S4), and 3 males that are not included in the model (red symbols)