Spectrograms of elephant vocalization playback stimuli.

<p>A) Samburu multi-call alarm: unmodified vocal response to Samburu voice playback, with rumbles (black arrows) and roars and trumpets (white arrows). Nonlinear phenomena include chaos in roars, and bifurcation in one rumble (R3) and the second roar which transitions to a rumble (R4). B) Samburu rumble alarm: same as (A) but with roars and trumpets removed. Rumbles overlapping with roars (R2 and second half of R3) were simultaneously removed. The remaining rumbles were doubled. First and second formant (F1, F2) locations are indicated. C) Modified Samburu rumble alarm: same as (B) but with F2 lowered to resemble control rumbles. See Materials and Methods for details. Spectrograms were created in Adobe Audition (version 2.0, 44.1 kHz sample rate, frequency resolution = 8192 bands, Gaussian window).