Elephant calls that humans can't hear.Elephant calls that humans can't hear Don't look now
Don't Look Now is an Anglo-Italian thriller, directed by Nicolas Roeg and released in 1973. It is based on a short story by Daphne du Maurier. , but the largest land animals may be talking behind our backs. Cornell university Cornell University, mainly at Ithaca, N.Y.; with land-grant, state, and private support; coeducational; chartered 1865, opened 1868. It was named for Ezra Cornell, who donated $500,000 and a tract of land. With the help of state senator Andrew D. researchers have discovered that elephants produce low-frequency sounds inaudible to humans but well suited to communicating within herds. The sounds, probably produced by the elephant's 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 , set up a sympathetic vibration Sympathetic vibration The driving of a mechanical or acoustical system at its resonant frequency by energy from an adjacent system vibrating at this same frequency. in its forehead. Seeing that flutter and feeling a throbbing throb intr.v. throbbed, throb·bing, throbs 1. To beat rapidly or violently, as the heart; pound. 2. To vibrate, pulsate, or sound with a steady pronounced rhythm: sensation in the air led Katharine Payne, William Langbauer Jr. and Elizabeth M. Thomas to discover the infrasonic infrasonic /in·fra·son·ic/ (-son´ik) below the frequency range of sound waves. in·fra·son·ic adj. Generating or using waves or vibrations with frequencies below that of audible sound. sounds. The vibrations were measured at 14 to 24 hertz. (The human hearing threshold is about 30 hertz, unless sounds are very intense.) Asian elephants are known to be capable of detecting tones with frequencies of 17 hertz, and Asian and African elephants alike probably can hear sounds of much lower frequencies than that, Langbauer says. "We were only getting part of the picture in the past," says Thomas Lovejoy of the World Wildlife Fund in Washington, D.C., which is one of the project's sponsors. "The interesting question, of course, is whether there were certain kinds of things they were communicating so that we couldn't hear." The researchers don't know Don't know (DK, DKed) "Don't know the trade." A Street expression used whenever one party lacks knowledge of a trade or receives conflicting instructions from the other party. for certain whether the elephants use these sounds to communicate. If they do, the infrasonic calls might indeed serve a different purpose than harder-to-miss bellows, since low-frequency sounds travel farther than those bellows in forests and open plains. Long-distance, low-frequency communication could explain puzzling aspects of elephant behavior, including the ability of males to find females during the brief conjunction of male "must" (heightened sexual activity) and female fertility; and the highly coordinated movements within herds that seem to occur without signaling. In July, the researchers will travel to Namibia, in southwest Africa, to investigate the distance over which elephants can hear the infrasonic calls, and to look for correlations between the calls and elephants behavior. |
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