Purr

A purr is a tonal fluttering sound made by some species of felids and two species of genets. It varies in loudness and tone among species and in the same animal. A purr is a tonal fluttering sound made by some species of felids and two species of genets. It varies in loudness and tone among species and in the same animal. Although true purring is exclusive to felids and viverrids, other animals such as raccoons produce purr-like vocalization. Animals that produce purr-like sounds include mongoose, bears, badgers, foxes, hyaenas, rabbits, squirrels, guinea pigs, tapirs, ring-tailed lemurs, and gorillas while eating. The mechanism by which cats purr is an object of speculation. There is a unique “neural oscillator” in the cat’s brain of uncertain significance. One hypothesis, backed by electromyographic studies, is that cats produce the purring noise by using the vocal folds or the muscles of the larynx to alternately dilate and constrict the glottis rapidly, causing air vibrations during inhalation and exhalation. Combined with the steady inhalation and exhalation of air as the cat breathes, a purring noise is produced with strong harmonics. No cat can both purr and roar. The subdivision of the Felidae into “purring cats” on one hand, and “roaring cats” on the other, goes back to Owen (1834/1835) and was definitively introduced by Pocock (1916), based on whether the hyoid bone of the larynx is incompletely (“roarers”) or completely (“purrers”) ossified. However, Weissengruber et al. (2002) argued that the ability of a cat species to purr is not affected by the anatomy of its hyoid. The “roaring cats” (lion, Panthera leo; tiger, P. tigris; jaguar, P. onca; leopard, P. pardus) have an incompletely ossified hyoid, which according to this theory, enables them to roar but not to purr. However, the snow leopard (Uncia uncia, or P. uncia), as the fifth felid species with an incompletely ossified hyoid, purrs (Hemmer, 1972).