To play the bridged zithers of East Asia (the gayageum, the Chinese zheng, the Japanese koto, the đan tranh from Vietnam and the yatga from Mongolia…) is a little bit like playing rubber bands with your fingers. Pull tighter and the pitch rises. Because of the bridges, known in Korea as wild goose feet (雁足), by pushing instead of pulling you can do a lot to “play” with a pitch as it decays into silence after being plucked into existence. This vibrato?nonghyeon in Korean, literally, “string play”?contains multitudes: entire countries, genres, and schools are encoded in one bend. A single pluck tells you how long a player has been playing, where they are from, what they listen to, even something of their personality. All of this lives not in the instrument itself but in the body of the player?their heart, their muscles, their skin, their ears. It is what transforms the instrument from a simple board with strings stretched over it, suspended by “bridges,” into a national instrument capable of hosting its own gods and expressing the hearts of a people at a certain moment in time. Materials matter, of course?paulownia, chestnut, silk, steel, tetron, ivory, tortoise shell, bamboo…. But what is housed in the body of a player matters most.

I recently returned from Jindo, an island so thick with designated intangible heritage?Jindo Arirang, Ganggangsullae, dasiraegi, ssitgimgut?that it was made the country’s only “folk arts special district.” They say you should not bother with the modest brag in Jindo. Many of the famous historical Korean artists are from there, and the locals are all better than you. Thus, last weekend, I was nervous to sing a Jeollanese song at the National Namdo Gugak Center for a local audience with such well-seasoned ears. After decades of practice, I mostly know how to make Jeollanese vibrato with my hands on a string, but the deep, wide vocal vibrato required to sing Jindo Arirang?the same voice that calls the dead home in Jindo’s ssitgimgut?that is another matter. I attempted the gayageum byeongchang danga “Song of Youth” and came away more relieved to have remembered all the classical Sino-Korean lines than proud of my vocal prowess.

While preparing, however, I found myself thinking about the vocal production of Jindo Arirang compared with the very different character of Bonjo Arirang, the “original” familiar Gyeonggi/Seoul version, and about vibrato in general?how it reflects the disposition of a particular people in a particular place and how it seems to be slowly fading from genres everywhere at once.

Last fall, at a conference in Nanjing, a friend invited a zheng (箏) player to entertain us. The young woman taped eight picks to the pads of her fingers. When I was studying zheng in China in the early 90s, everyone played with three picks, all on the right hand, leaving the other fingers bare to create softer timbres to the right of the bridges and, on the left, to decorate the waning reverberation. That night in Nanjing, only the pinkies and the narrow crescent moon slivers of flesh between the picks and the young woman’s fingernails were available to control the vibrato that “embroiders” the decay of each plucked note. The aesthetics of the zheng have obviously changed since I was a student. What my teachers called timbral nuance has given way to virtuosity that is fast, contrapuntal, and harmonically Western. The elder calligrapher at the party that night lamented the change bluntly?a man who has spent his life judging whether a line is alive. In Korean terms, there is a loss of sigimsae: reverence for the life of a single tone; the respect owed to its particular bent shape as it arrives and leaves?shapes one also finds in a dance like salpuri. The famous gayageum player, Ji Seongja, has a name for what is left when a string sounds without the weight of a human hand shaping its diminuendo. She calls it a “dead sound”?a string with no gi (氣).

This is not just a guoyue or gugak problem. A few years ago, on the American podcast Rock Guitar Confidential, two guitar teachers discussed their students’ relationship with vibrato, noting it “is not in their ears.” Their students listen to electronic music that does not bend, and thus file bending under things the older generation does. The teachers worried that a whole generation was about to grow up “not really sounding like humans”?more like people who fell down a flight of stairs with a MIDI controller.

On the European podcast Unboxing Women, two professional pop singers worked their way toward the uncomfortable realization that vibrato, especially that of women, disappears in studio recordings and then realized that live performance no longer offers any real refuge either, with pop vocals now routinely tech-corrected onstage as well.

Autotune is worth thinking about as a predecessor to what we now call AI in that, once each has established a model of correctness, it enforces it. A pitch becomes a point rather than a path. The machine aims at a discrete target, snaps transitions into steps, and reads oscillation around a center as deviation to be hauled back in. It recognizes vibrato as error in need of correction. Each curved tone is pulled straight, dehumanizing the sound.

The American composer Ken Ueno calls these “systems not built to hear us.” He uses the example of the blues guitarist B.B. King, noting that “King’s bends … do not simply represent feeling?they perform it. And it’s that performative excess, that resistance to smooth representation, that AI struggles to recognize, let alone replicate.” The result is, as he says, “plausible enough to pass as real but unmoored from lived experience”?a reality “continuously recomposed in the image of its representations.”

If, as the anthropologist Laurel Kendall says, it takes human agency to invite divine presence into otherwise inanimate objects?to invite the spirits to dance upon the strings of a gayageum?human agency can also occasion their departure. In the age of artificial intelligence, as we begin to mistake the smooth even perfection of the machine for the divine, the departure does not at first sound like a loss. It can sound like an in-tune pop star, or the utterly benign AI-generated music at my coffee shop. But as the spirits stop dancing on the strings, masters like Ji Seongja will always strain to hear in those dead sounds the humans and the gods who have gone missing.