African elephant rumbles from one female in three social contexts. Social contexts and acoustic analyses are described in Methods section. Spectrograms (lower panel), F 0 contours (middle panel), and Fourier spectra (upper panel) are shown. In the upper panel, smoothed Fourier spectra indicate the first two formant frequency locations and vertical lines show H1 − H2 spread. Spectrograms are narrowband (window length = 0.25 Hz, time step = 0.003 s, frequency step = 1 Hz; Gaussian window).
Schematic of the dimensional approach to affect indicating intensity and quality dimensions. Social contexts are placed in the affect space based on their purported relative intensities and qualities (black circles). Error bars in the high intensity contexts indicate uncertainty as to relative levels of intensity but indicate that both are of higher affect intensity than the neutral social context.
Acoustic responses across social contexts, with results of pair-wise tests. Means ± standard error of the mean for acoustic variables in each social context are shown (Neu = neutral; Pos = positive; Neg = negative). p = significantly different from the positive social context (Tukey’s post-hoc tests, p < 0.05); n = significantly different from the negative social context (p < 0.05).
Acoustic properties of rumbles across affect contexts (mean ± SD).
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