among some nonhuman animals, the use of sound frequencies below the range of human hearing (i.e., below 20 Hz) for communication. Both elephants and whales use infrasonic communication extensively. The low frequencies have very long wavelengths that are transmitted for very long distances: They have been shown to coordinate activity between individuals over distances of several kilometers. Compare ultrasonic communication. [discovered in the 1980s by Cornell University researcher Katharine Boynton Payne (1937– )]