From our journal article: Reber, S. A., Nishimura, T., Janisch, J., Robertson, M. and Fitch, W. T. (2015). A Chinese alligator in heliox: formant frequencies in a crocodilian. J. Exp. Biol. 218, 2442-2447. https://doi.org/10.1242/jeb.119552
“Once humans master verbal communication, we babble incessantly on any topic under the sun. But even animals that are equipped with less sophisticated communication systems depend on the same resonances that we skilfully shape with our vocal tracts for communication. Stephan Reber from the University of Vienna, Austria, explains that vibrations – produced when air is pushed past the vocal folds – force air trapped in the vocal tract to vibrate (resonate) and it is these resonances that shape bird song and human syllables. “