One in ﬁve teenagers in America can’t hear rustles or whispers, according to a study published in August in The Journal of the American Medical Association. These teenagers exhibit what’s known as slight hearing loss, which means they often can’t make out consonants like T’s or K’s, or the plinking of raindrops. The word “talk” can sound like “aw.” The number of teenagers with hearing loss — from slight to severe — has jumped 33 percent since 1994.

Given the current ubiquity of personal media players — the iPod appeared almost a decade ago — many researchers attribute this widespread hearing loss to exposure to sound played loudly and regularly through headphones. (Earbuds, in particular, don’t cancel as much noise from outside as do headphones that rest on or around the ear, so earbud users typically listen at higher volume to drown out interference.) Indeed, the August report reinforces the findings of a 2008 European study of people who habitually blast MP3 players, including iPods and smartphones. According to that report, headphone users who listen to music at high volumes for more than an hour a day risk permanent hearing loss after five years.

Maybe the danger of digital culture to young people is not that they have hummingbird attention spans but that they are going deaf.

The history of headphones has always been one of unexpected uses and equally unexpected consequences. Headphones were invented more than a century ago. According to some accounts, modern headphones were the brainchild of Nathaniel Baldwin, a tinkerer from Utah who grew frustrated when he couldn’t hear Mormon sermons over the noise of the crowds at the vast Salt Lake Tabernacle. Baldwin’s device, which was designed first as an amplifier, came to incorporate two sound receivers connected by an operator’s headband. Within each earphone was, according to legend, a mile of coiled copper wiring and a mica diaphragm to register the wire’s signals with vibrations. When the Navy put in an order for 100 such Baldy Phones in 1910, Baldwin abandoned his kitchen workbench, hastily opened a factory and built the prosperous Baldwin Radio Company. His innovations were the basis of “sound powered” telephones, or phones that required no electricity, which were used during World War II.