Topic: Heap’s power law

Animal vocal sequences including human speech are organized into hierarchical sequences composed of voice primitives. In human speech, these primitives are known as phonemes or phones. By contrast, the corresponding vocal primitives in animals have been poorly studied. What sets of vocal gestures span the vocal repertoire of an animal and what regularities apply to animal vocal repertoires across individuals and across species? In birdsong, the roughly hundred-millisecond long song syllables are often considered basic vocal units, since syllables display little acoustic variability within t