Here are the videos accompanying my paper Fitch, W. T. (2000). “The phonetic potential of nonhuman vocal tracts: Comparative cineradiographic observations of vocalizing animals,” Phonetica 57, 205-218. PDF
The key finding of this work is that animal vocal tracts are highly flexible, dynamically reconfigurable systems. This means that earlier assumptions based on anatomy of dead animals provide a poor indication of what animals can and can’t do with their vocal tracts. This has important implications for arguments about the evolution of speech. Please see the paper for details of how, why and where this was done.
In all of the mammals we have looked at, the larynx lowers during vocalization. You can see this for yourself in these videos. In the case of dogs, the larynx lowers quite considerably, down to the base of the neck, and pulls the tongue down with it. In the case of the goat the lowering is less pronounced: just enough to get the larynx down out of the nasal cavity, where it rests during resting breathing.
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