In 1989, “acoustic ecologist” Gordon Hempton received a grant to document and record the natural sounds of Washington state. He identified 21 wilderness places to record—sites unsullied by the sounds of traffic, aviation, construction, and other man-made noise. Twenty-five years later, only three of those sites remain muted.Little by little, our world is becoming louder, with the creeping spread of noise pollution infiltrating our homes, our workplaces, and even our wilderness. Hempton, whose work for the past 30 years has been traveling the world to survey and record natural sound, says he’s seen firsthand how the hum, ping, and roar of modern life has taken over our soundscape. By his count, the United States has only 12 remaining truly “quiet places,” which he defines as somewhere you can go for at least 15 minutes without hearing artificial sound at dawn, the hour when sound travels farthest.“That dawn period is a really important time, because it’s when wildlife can vocalize and send their message the greatest distance with the least energy,” he says. “It’s a beautiful time to listen.”With his nonp …