Aroar/rɔːr/ⓘ is a type ofanimal vocalization that is loud, deep andresonating. Manymammals have evolved to produce roars and other roar-like vocals for purposes such as long-distance communication and intimidation. These include various species ofbig cats,bears,pinnipeds,deer,bovids,elephants, andsimians.
The anatomical basis for the ability to roar often involves modifications to thelarynx andhyoid bone and enlarged internal air spaces for low-frequencyvocal resonation. While roaring, animals may stretch out their necks and elevate their heads to increase the space for resonance.
The definition of "roar" has varied between species.[1] However Weissengruber et al. (2002) has given a more general description of roars as consisting of both a lowpitch and lowformant.[2][1] They have used the roars oflions andred deer as quintessential examples of the sound.[2] Other researchers have mentioned similar "roar-like" vocalizations where either the pitch or formant is still higher than in true roars.[1]
Roaring mammals have evolved various means to achieve their vocalizations. A proportionally largelarynx contributes to a deeper pitch. The male hammer-headed bat has a larynx that takes up most of his thoracic cavity and is half the size of his backbone. A larger larynx also has enlargedvocal cords which contributes to a deeper pitch and more massive folds leads to sloweroscillation.[1] In addition, the big cats (lion,tiger,jaguar andleopard, referred to as the "roaring cats"), have vocal cords that are square-shaped as opposed to the triangle-shaped cords of otherfelids; this allows them to produce a louder call with less lung pressure.[2] The elasticity of the larynx and the length of thevocal tract affect the formant or resonance of a sound. In big cats and some male deer, specialized musculature and ligaments pull the larynx deeper in the vocal tract when roaring, lowering the vocal tract resonance.[1]
Other species have evolved internal inflatable air spaces connected to the vocal tract, which play a role invocal resonance. The maleMongolian gazelle andmusk ox possess an air space (paired and two-chambered in the former) attached to the larynx,[1] while bears have such spaces connected to thepharynx.[3][1] Male howler monkeys have an unpaired rostroventral laryngeal air sac within the hyoid bulla (extension of thehyoid bone) and a pair of ventral laryngeal air spaces outside.[4] The hammer-headed bat has a pouch in thepalatine that connects to an enlargednasopharynx region, in addition to paired cheek pouches which extend to therostrum.[1] Elephants possess a pharyngeal pouch associated with their larynx and hyoid apparatus, and their roars can also be modified by the nostrils in their trunks.[5] Maleelephant seals andsaiga antelopes have an enlarged and inflatedproboscis, which also affects resonance. Saiga nevertheless roar with their mouths closed and produce a "nasal roar".[1]
The structure of the hyoid bone can play a role in an animal's ability to roar. The hyoid of the big cats is less ossified and more flexible than in other cats. Thesnow leopard also has this property, but cannot roar, as its shorter vocal folds provide little resistance to airflow.[2][6] In howler monkeys, the hyoid bone is relatively large and cup-shaped, contributing to the depth and resonance of the call.[4] Though usually airborne, some roars are emitted underwater, as in the case of the maleharbor seal.[1]
In some species, roars evolved due tosexual selection, and only one sex roars.[1] For example, ingorillas only the adult male (silverback) has a larynx large enough and vocal cords lengthened enough to produce a full roar.[7] Nonetheless, in other species both sexes can produce these vocalizations. In lions, where both sexes roar, the vocalization plays a role in social spacing and territorial defense. The roars ward off other lions from mistakenly entering another lion's territory. The roar of a lion is audible for up to five miles in human hearing and probably further for lions.[8][9][10]
The lion's roar is familiar to many throughLeo the Lion, the iconiclogo seen during the opening sequence ofMGMfilms. Leo's current roar, recreated byMark Mangini in 1982 and redone in 1994 and 1995, consists of tiger growls instead of actual lion roars. As Mangini later stated, "lions don't make that kind of ferocious noises [sic], and the logo needed to be ferocious and majestic".[11]
