Frogs that talk through their ears.The commanding croak of the North American North American named after North America. North American blastomycosis see North American blastomycosis. North American cattle tick see boophilusannulatus. bullfrog bullfrog, common name of the largest North American frog, Rana catesbeiana. Native to the E United States, this species has been successfully introduced in the West and in other parts of the world. The body length is 4 to 8 in. is broadcast mostly through its ears, says Alejandro P. Purgue of the University of California, Los Angeles UCLA comprises the College of Letters and Science (the primary undergraduate college), seven professional schools, and five professional Health Science schools. Since 2001, UCLA has enrolled over 33,000 total students, and that number is steadily rising. . Purgue demonstrates his discovery by covering a croaking frog's ears with his fingers. The ribbets sound muffled muf·fle 1 tr.v. muf·fled, muf·fling, muf·fles 1. To wrap up, as in a blanket or shawl, for warmth, protection, or secrecy. 2. a. , like someone trying to shout through a gag. Like other frogs and toads, the North American bullfrog generates the basic sound of its call with its vocal cords vocal cords: see larynx. Vocal cords The pair of elastic, fibered bands inside the human larynx. The cords are covered with a mucous membrane and pass horizontally backward from the thyroid cartilage (Adam's apple) to insert on . However, ear membranes on each side of its head resonate with several of the key frequencies, amplifying and broadcasting the call, Purgue reports in the November 1997 Journal of Comparative Physiology A. He calculates that ear power accounts for some 90 percent of the volume of a bullfrog croak. "It's a mystery so far how they don't make themselves deaf," he says. Six additional, closely related frog species have loudspeaker ears, the researcher reports, whereas western chorus frogs and California tree frogs use other body parts as resonators. Purgue uncovered the ear phenomenon while investigating a long-standing puzzle about vocal sacs in frogs and toads. Scientists had once assumed that these pouches, which open into the mouth, acted as resonators, amplifying sound, but several experiments failed to demonstrate the effect. A research team at the University of Texas at Austin “University of Texas” redirects here. For other system schools, see University of Texas System. The University of Texas at Austin (often referred to as The University of Texas, UT Austin, UT, or Texas had searched for resonance by tucking frogs into bags of helium to see whether their calls turned squeaky, much as gulps of helium from a birthday balloon change the resonant properties of the human vocal tract to produce a Mickey Mouse voice. The helium had no effect on frog calls, Robert Dudley and A. Stanley Rand concluded in 1993, so they dismissed the idea of vocal sacs as resonating cavities. Purgue took a different approach, checking vibration in the walls of vocal sacs and other tissues when he played a range of frequencies. The patterns he found indicate that the sac walls of several species resonate, as do the big ears of the bull-frog. For a high-tech demonstration of how covering frogs' ears quiets their croaks, Purgue crafted bits of foam and a spring into frog earmuffs Earmuffs are objects designed to cover a person's ears for protection. They consist of a thermoplastic or metal head-band, that fits over the top of the head, and a pad at each end, to cover the external ears. . |
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