Speaker
Description
We present a pipeline for extracting and analyzing the fundamental frequency (F0) contour patterns in the rumbles of African savanna elephants (Loxodonta africana). Rumble F0s can go as low as 15 Hz and are often masked by infrasonic background noise or overlap with other calls, making standard contour extraction methods perform poorly. To address this, we introduce a custom infrasonic-adapted time-frequency representation and a three-stage extraction procedure: (i) tracking spectral peaks of the first harmonic, (ii) manual inspection and correction in a GUI, and (iii) refinement of the final F0 contour by maximizing harmonic coherence at a higher time resolution. Once extracted, we analyze the F0 contours of approximately 1,600 rumble recordings using unsupervised methods to identify groups based on different contour features, with particular emphasis on amplitude and frequency modulation patterns. Matching these patterns with behavioral observations and contextual data will provide a more in-depth view of the use of modulation in elephant acoustic communication.