"long-term exposure to loud noise damages hearing and is associated with an increased risk of heart attack. so what if we were able to step into a portable sphere of pure silence? imagine soundproofed homes perched next to freeways, expanded flight corridors for now-silent jets and quiet slices of heaven for people who work or live in noisy environments, such as city streets, construction sites or crowded coffee shops. noise-canceling headphones already exist- they use an external microphone to detect incoming noise and then generate sounds that are 180 degrees out of phase. the two sound waves cancel each other out—a phenomenon known as destructive interference—but the process only works for low-frequency sound. it’s a good start, but the real deal may be on the horizon. a recent article i"
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