I sat with Jay Michaels one morning this spring while he worked on the Beat’s weekend playlist. His office is tiny, airless and cluttered with Hello Kitty lunchboxes, promotional teddy bears, novelty coffee cups and rubber duckies. On his computer, he had loaded Stratus, Cumulus’s proprietary music-­scheduling software. He pressed a button, and dozens of songs populated a grid on the screen, color-coded in a pattern that Michaels refused to explain. Michaels and Morris are cagey about Stratus, which is used companywide but customized by each station. They refer to the software as their ‘‘secret sauce.’’ What I gleaned through later conversations is that Michaels has broken hip-hop down by region and into subgenres, and the Beat uses these metadata tags to keep its playlist diverse.

On Cumulus’s version of the format, you’ll never hear back-to-back-to-back Southern rap hits or a cluster of R & B songs with female vocalists; the Beat will break up a block of tunes by harder artists like Ice Cube or DMX with a Mariah Carey track. ‘‘Without flow, this format is a train wreck,’’ Michaels said as he sifted through the computer’s selections, massaging the playlist. ‘‘It’s me being overly anal. I have my own rules.’’ Among them: Notorious B.I.G. and Tupac should never be played back to back (it might call to mind their deadly feud), and a Biggie song should never be played before or after ‘‘I’ll Be Missing You,’’ the tribute song Puff Daddy recorded after Biggie was killed. Michaels also won’t play Outkast next to Ludacris — it just feels weird.

The Beat is just one of several stations experimenting with the format now, and certainly such rules differ in each city. But the basics of the formula are the same that were developed by Radio One in October. That was the month the company unplugged a failing news station in Houston, 92.1 KROI-FM, dismissed all the employees and started playing Beyoncé songs, commercial-free, 24 hours a day. Beyoncé’s fans — the BeyHive — went bonkers. News outlets from all over the country called with questions about the odd format. On the afternoon of the fifth day, the station paused for a commercial and then played ‘‘Mind Playing Tricks on Me’’ by the Geto Boys, arguably Houston’s most famous contribution to rap music. Notorious B.I.G. followed, then Tupac, then Salt-N-Pepa.

The early ratings returns were astounding. The station’s audience shot to 802,000 from 245,000, and its Nielsen share went to 3.2 from 1.0. Shortly after that, Radio One started similar stations in Philadelphia and Dallas and saw a gain of 200,000 listeners in each of those cities. Soon, 15 more stations, including 93.9, made the switch.

A cynical but not inaccurate way of thinking about radio formats is as a tool to segment the population for advertisers. Ancient and unglamorous as it may be, radio remains a potent vehicle for advertisers to access consumers. According to a 2015 Nielsen Audio Today report, 91 percent of Americans age 12 or older listen to the radio each week, and the vast majority of those listeners are in the work force (which means they have money to spend). According to another Nielsen study, advertisers achieve more than $6 of incremental sales for every $1 spent on the radio. For radio-station owners, the business plan is simple: Attract the broadest possible audience to your programming and then do everything you can to keep them listening. This is why radio professionals talk about musical genres in ways normal human beings do not; no one believes she listens to rhythmic adult contemporary, but in aggregate, millions of people between the ages of 25 and 54 do.

The Beat, and stations like it, target listeners in their mid-20s to mid-40s: people who grew up during rap’s golden era. This is a subset of the population that is outgrowing contemporary hip-hop radio (which targets the 18-34 demographic) but is mostly too young to be nostalgic for ’70s and ’80s stations and too hip for adult contemporary. They are also entering the prime spending years of their lives — marriage, children, car buying and homeownership — and radio, like all forms of media, is figuring out how to catch them.