Sound Visualization Demonstrates Velopharyngeal Coupling and Complex
Spectral Variability in Asian ElephantsVeronika C. Beeck, Gunnar Heilmann,
Michael Kerscher & Angela S. StoegerAnimalsAugust 18, 2022Abstract
Sound production mechanisms set the parameter space available for
transmitting biologically relevant information in vocal signals.
Low–frequency rumbles play a crucial role in coordinating social
interactions in elephants’ complex fission–fusion societies. By emitting
rumbles through either the oral or the three-times longer nasal vocal
tract, African elephants alter their spectral shape significantly. In this
study, we used an acoustic camera to visualize the sound emission of
rumbles in Asian elephants, which have received far less research attention
than African elephants. We recorded nine adult captive females and analyzed
the spectral parameters of 203 calls, including vocal tract resonances
(formants). We found that the majority of rumbles (64%) were nasally
emitted, 21% orally, and 13% simultaneously through the mouth and trunk,
demonstrating velopharyngeal coupling. Some of the rumbles were combined
with orally emitted roars. The nasal rumbles concentrated most spectral
energy in lower frequencies exhibiting two formants, whereas the oral and
mixed rumbles contained higher formants, higher spectral energy
concentrations and were louder. The roars were the loudest, highest and
broadest in frequency. This study is the first to demonstrate
velopharyngeal coupling in a non-human animal. Our findings provide a
foundation for future research into the adaptive functions of the elephant
acoustic variability for information coding, localizability or sound
transmission, as well as vocal flexibility across species.
FULL PAPER PDF
LINKhttps://drive.google.com/file/d/1ffeRf76L-0ZpuzxkPqIHZa8WXHNIjBIL/view?usp=sharing
https://drive.google.com/file/d/1ffeRf76L-0ZpuzxkPqIHZa8WXHNIjBIL/view?usp=sharing
FULL
PAPER WEB LINKhttps://www.mdpi.com/2076-2615/12/16/2119/htm
https://www.mdpi.com/2076-2615/12/16/2119/htm