From “How Headphones Changed the World,” Derek Thompson’s Atlantic article about the unusual origins of the tech item, which was invented by Nathaniel Baldwin, a Mormon supporter of the polygamist movement:

“In 1910, the Radio Division of the U.S. Navy received a freak letter from Salt Lake City written in purple ink on blue-and-pink paper. Whoever opened the envelope probably wasn’t expecting to read the next Thomas Edison. But the invention contained within represented the apotheosis of one of Edison’s more famous, and incomplete, discoveries: the creation of sound from electrical signals.

The author of the violet-ink note, an eccentric Utah tinkerer named Nathaniel Baldwin, made an astonishing claim that he had built in his kitchen a new kind of headset that could amplify sound. The military asked for a sound test. They were blown away. Naval radio officers clamored for the ‘comfortable, efficient headset’ on the brink of World War I. And so, the modern headphone was born.”

••••••••••

Headphones on display in a 1970s Continental ad: