Triple A radio is producing some major league hits.

The niche format (whose nickname is shorthand for “adult album alternative”) nurtured the top Billboard Hot 100 title of 2011, Adele‘s “Rolling in the Deep.” The song spent 14 weeks at No. 1 on the Nielsen BDS-based Triple A chart – the first ranking on which it appeared before crossing to pop, adult and even R&B and Latin radio.

Triple A also championed Gotye‘s “Somebody That I Used to Know,” featuring Kimbra, which, earlier this year led Triple A for 13 weeks and the Hot 100 for eight, making it a front-runner for this year’s biggest Hot 100 hit.

Triple A likewise shone on Nielsen SoundScan’s recently-released midyear sales tallies, where Adele’s 21 ranked as the top-selling album of the first half of 2012 (3.7 million units) and Gotye’s smash earned top-selling digital song honors (5.5 million downloads).

The success of “Somebody” especially underscores the format’s swelling acceptance of new artists. The song’s Triple A command began an active 23-week streak of artists reigning on their first visits to the survey (viewable at Billboard.biz). Following “Somebody,” Of Monsters and Men‘s “Little Talks” led for four weeks and Alabama Shakes‘ “Hold On” ruled for one. As of this week, the Lumineers‘ “Ho Hey” has spent five weeks on top. Since the chart launched the week of Jan. 20, 1996, never before had four rookie acts reached No. 1 consecutively.

Other debut singles finding success at the format include Imagine Dragons‘ “It’s Time” (at No. 2 this week), Ed Sheeran‘s “The A Team” (No. 3) and Grouplove‘s “Tongue Tied” (No. 6).

The domination of fresh triple A blood challenges the format’s reputation as a haven for rock acts with decades-long discographies. Just one artist appears on this week’s Triple A ranking whose Billboard chart history predates the ’90s: Bonnie Raitt. A year ago this week, there were three (Paul Simon, Lenny Kravitz and the Cars). Five years ago this week, there were five.

Why a more favorable reception of somebodies that we previously didn’t know?

Cumulus San Francisco director of FM programming Dennis Constantine, who oversees triple A KFOG, credits the impact of the digital era on consumer behavior in aiding new artists’ growth. “More than ever, music is about songs. More people are buying downloads of individual songs than buying a full album. So, we’re finding new, creative songs from unknown artists.”

Triple A programmers and label promotion executives cite social media as helping demystify new artists. “The internet, mobile phone, Facebook and Twitter have accelerated familiarity to listeners who use these portals for music discovery,” says Lauren MacLeash, PD of Clear Channel-owned KTCZ Minneapolis.

Social media have buoyed promotion of Sheeran’s debut single. “We could only get Ed to Nashville on a Monday and all the major venues there were sold out,” Atlantic Records director of triple A promotion Brian Corona recalls. “With (Tuned In-owned) WRLT’s relationship with 3rd and Lindsley Bar and Grill, we were able to schedule a 6 p.m. showcase. Through social media messaging, when arrived at sound check at 3, there were already more than 200 people there, camped out and lined up around the block.”

The building popularity of multi-artist festivals likewise plays into triple A’s riches of new talent.

“SXSW this year was huge for the Lumineers,” says Dualtone director of promotions Lori Kampa. “I was lucky enough to be at some of the band’s first headlining shows afterward and fans were singing along to almost every word.” Additionally citing synchs, including Fox’s “American Idol,” Kampa says that when Dualtone began promoting “Ho Hey” to radio, awareness of the group was already high. “It was a record that made sense for programmers to step out on because we had built amazing success that continued to grow.”

At its best, Chris Mays, PD of Alpha’s KINK Portland, Ore., muses, triple A programming is a “balancing act” of the best new artists and old favorites: “How can you resist playing the Black Keys alongside a classic Rolling Stones song?”

MacLeash says that the current success of triple A’s newer acts ultimately promises benefits going forward.

“Popular music comes in cycles. The pendulum is swinging in triple A’s favor,” she says. “Adele, Gotye, Jason Mraz and others being accepted by top 40 means that the young end is into the new music we play. Long-term, that’s so important to our survival.”