Vocal size exaggeration may have contributed to the origins of vocalic complexity

Vocal tract elongation, which uniformly lowers vocal tract resonances (formant frequencies) in animal vocalizations, has evolved independently in several vertebrate groups as a means for vocalizers to exaggerate their apparent body size. Here, we propose that smaller speech-like articulatory movements that alter only individual formants can serve a similar yet less energetically costly size-exaggerating function. To test this, we examine whether...