Before satellite imagery brought the whole Earth into perpetual view, infrasound arrays were deployed by the United States military to listen in on activity from across the globe. These instruments measure slight changes in atmospheric pressure—sounds—that have traveled huge distances but which are too low in frequency for human ears to ordinarily perceive. Subsequent treaties and technologies made listening for distant nuclear warhead tests largely obsolete, and yet much is still audible when the air we breathe is understood as a shared medium.
If a “microphone” is a device used to amplify small sounds, an infrasound array could be called a "macrophone” as it brings very large and low sounds into our perceptual range—sounds from hurricanes, heavy industry, calving icebergs, wind turbines, sagging infrastructure, or police weaponry. So often these phenomena, that have everything to do with the climate crisis, are made invisible to the communities that they affect, as the digital platforms of perspective are expensive instruments of power and are easily manipulated. But macrophones can be built on the ground, in your backyard. In this time of social distancing, what can we hear when we listen in?