Fig. 5
From: A novel theory of Asian elephant high-frequency squeak production
Spectrograms: a–d Squeaks from four different adult female Asian elephants demonstrating intra-individual (a + b) and interindividual (a–d) variability in spectral and temporal features and containing examples of nonlinear phenomena: a long squeaks that were emitted as single calls and concatenated for display (f, 55 years), b short squeaks that were emitted in a bout (f, 23 years); c f, 60 years, d f, 48 years, e the first author whistling; f a balloon when letting the air stream through its tensed neck; and g the first author buzzing her lips