Sound Visualization Demonstrates Velopharyngeal Coupling and Complex Spectral Variability in Asian Elephants
Veronika C Beeck1, Gunnar Heilmann2, Michael Kerscher2
1Department of Behavioural and Cognitive Biology, University of Vienna, 1030 Vienna, Austria.
Animals : an Open Access Journal From MDPI
|August 26, 2022
Summary
Asian elephants produce low-frequency rumbles using both nasal and oral vocal tracts, demonstrating velopharyngeal coupling. This vocal flexibility impacts sound characteristics, offering insights into elephant communication.
Area of Science:
- Bioacoustics
- Animal Communication
- Mammalogy
Background:
- Low-frequency rumbles are vital for social coordination in elephant societies.
- African elephants modify rumble acoustics via oral vs. nasal vocal tracts.
- Asian elephants, less studied, also utilize complex vocalizations.
Purpose of the Study:
- To investigate sound production mechanisms in Asian elephants using an acoustic camera.
- To analyze spectral parameters and vocal tract resonances (formants) of elephant rumbles.
- To determine the prevalence of nasal, oral, and combined vocalizations and identify velopharyngeal coupling.
Main Methods:
- Recorded and analyzed 203 rumble calls from nine adult captive Asian female elephants.
- Utilized an acoustic camera for sound emission visualization.
- Analyzed spectral parameters, including formants and sound intensity.
Main Results:
- The majority of rumbles (64%) were nasally emitted, 21% orally, and 13% simultaneously (velopharyngeal coupling).
- Nasal rumbles featured lower frequencies and two formants; oral/mixed rumbles had higher formants, greater energy, and were louder.
- Roars were the loudest, highest, and broadest in frequency.
Conclusions:
- This study is the first to demonstrate velopharyngeal coupling in a non-human animal.
- Findings highlight significant acoustic variability in Asian elephant vocalizations.
- Provides a basis for understanding the adaptive functions of elephant acoustic variability and interspecies vocal flexibility.
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