Every second of every day unheard worlds tremble past my dim senses. Occasionally, when I’m in Africa, the air around me begins to thicken as an elephant’s vocalizations lift from infrasound into a register my ears can hear. Airquakes. Fractures and heaves of oscillating air. Another language, one without words, without speech.
I almost know infrasound. No more than two miles from my home freighters push through the deep waters of Puget Sound. On flat black nights the thump-thump of their propellers travels through water, through air, churns into my bed, my bones and into the lowest threshold of my hearing. It’s a mechanical throb, born in the bellies and boilers of machines, carried along rotating shafts which turn the metal blades of propellers, which slice through water like a dull knife hacking flesh. . . . . Whummp . . . whummp . . . whummp . . . . . . . . .
Out in the bay that fronts the town where I live, aggregates of barnacles coat docks and pilings and rocks. Their shells open and close, open and close, as feeding appendages catch food on the tides. Barnacle larvae hone in on the vibrations of feeding and settle in with their relatives so that they may easily exchange sperm and eggs with their kin. The sound of a large bed of barnacles can be heard for up to ten miles underwater.
Sound moves in waves similar to light waves. Light can be carried in a vacuum such as outer space but sound cannot. It needs a conducting medium. There’s a terribly silent universe beyond the top layer of earth’s atmosphere. It’s cold, breathless, without wind, without water, without life. On the moon our alien footfalls fell without sound into its dead dust. No one hears anything, unless you are in a spacesuit, listening to your own breathing.