As twilight deepens, the desert comes alive with sounds, from the pitter-patter of nearby mouse feet to the distant, eery call of a night bird.
But how does sound get from origin to ear, and what is it, anyway? To
understand, we must remember that we live at the bottom of a sea of air. Like the
ripples on a still pond radiating from the impact of a leaping fish, waves in the air
travel in all directions from their point of creation. Set into motion, whether by the
impact of mouse paw on sand or vibration of coyote vocal cords, air molecules collide
with their neighbors, nudging them away, and then rebounding into the rarefied space
just abandoned. Just as tripping off a row of dominoes results in action at a distance,
though any one domino moves only its length, waves of vibrating air travel until
scooped into the ear, transferring their energy to the eardrum and ultimately to the
brain, to be perceived as sound.
Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio, University of Texas at El Paso.