Since the 1960s, pop music has been ruled mostly by what’s known in the business — and to your ears — as the verse-chorus form: The verse sets the scene, the pre-chorus builds tension, and the chorus reaches a climax. Then, the cycle starts again: verse, pre-chorus, chorus. It’s the fun, if slightly predictable, roller coaster we’ve been riding for decades.

For a simple yet powerful and classic example, think back to “(You Make Me Feel Like) A Natural Woman” sung by Aretha Franklin. She starts out, “Looking out on the morning rain,” thinking of how she “used to feel so uninspired,” then brightens up talking about her new love, singing, “You’re the key to my peace of mind.” The instruments — horns, strings, drums — brighten up right alongside her and peak, cathartically, with the titular line everyone knows and loves (backed by a literal chorus).

Listeners loved this new form so much that it was soon the industry default. The music theorist Jay Summach has found that by the end of the 1960s, 42 percent of hit songs used verse-chorus form. By the end of the 1980s, that figure had doubled to 84 percent.

But things quickly began to shift in the 2010s. A mix of generational churn, creativity spawned by the digitization of music production and the dilution of the industry’s top-down structure — paired with the fragmentation of the media and adaptations to the streaming economy — has warped song structures. Beyond radio play, songs are five-second memes, 12-second TikTok soundtracks, 30-second ads and two-and-a-half-minute club anthems.

Listen to the Top 40 charts of the last decade and a surprising trend emerges. The form of pop as we know it seems to be changing before our ears. Take Billie Eilish’s “Bad Guy,” one of the biggest hits of 2019. It displays few of the values we typically associate with pop: the peaking decibel levels, the soaring melodies, the recurring phrases that are easy to sing along with, all wrapped into a steadily repeating climax that neatly tucks itself in between verses.