The rest of Sunday night's performances were by Mara Justine, a 15-year-old high school student from Galloway, NJ; Caleb Lee Hutchinson, a 19-year-old musician from Dallas, GA; Alyssa Raghu, a 16-year-old high school student from Orlando, FL; Effie Passero, a 26-year-old assistant property manager from Modesto, CA; Amelia Hammer Harris, a 26-year-old musician from Lexington, KY; Garrett Jacobs, a 17-year-old high school student from Bossier City, LA; and Shannon O'Hara, a 17-year-old nanny from Mooresville, NC.
These 12 contestants each performed a solo after being mentored by Bobby Bones, an on-air country radio personality, comedian and entertainer. Only seven of these singers will advance to the next round.
Katy previously told American Idol host Ryan Seacrest that the judges are looking for an "it factor" from the contestants as well as personality.
The judging panel is trying to establish what type of "unique contribution" each singer can bring to the music industry and how he or she might be able to cut through considering it's already jam-packed with talent.
The night of performances kicked off with Amelia singing "Believer" by Imagine Dragons.
Katy called Amelia "very versatile" and said she hopes the contestant will show all of her shades in this competition. Lionel noted she's "spectacular" and showed her experience on the stage.
Luke pointed out that Amelia had trouble finding her footing in the song at first, but he asked her not to let the judges down because they always had high hopes for her.
Lionel admitted Garrett didn't seem to concentrate on the vocals of the song, and while Luke agreed that he's not the best singer on the show, "he's such a doggone heartthrob."
Katy said Garrett is "fun to watch" but the song was "a rocky road" for him and he needs to make sure his vocals are smooth. Katy therefore advised the singer to relax and get out of his head.
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Maddie was up next, and she chose to perform "Brand New Key" by Melanie.
After receiving a standing ovation from the judges, Luke noted she had a moment on the stage and the song made him want to go skipping down a beach. He was "caught up in [her] artistry."
Katy called Maddie "infectious" and said she adores her and her authenticity. She and Lionel agreed Maddie knows who she is, no matter how far she goes on American Idol or what people think, and that's a star.
Ada Vox then belted out "Feeling Good" by Nina Simone, and she also got all three judges up on their feet.
"You are here to win," Katy said after getting on her knees to express her admiration.
"When we first saw you, we didn't know how this would fit into this thing," Lionel explained of Adam's drag-queen persona. "But your talent is so grand, it begs to put a new category in this equation because you are a force to be reckoned with."
Luke added that Ada -- who auditioned for American Idol 13 times -- brings the house down "every time" and it was unbelievable.
Caleb Lee then took the stage with "Die a Happy Man" by Thomas Rhett.
Lionel called the performance "simple and solid," and Katy expressed how there is a "timelessness" in his voice, which holds so much "wisdom and power." Luke noted Caleb has a subtle coolness about him but it wasn't the best song choice for him. Luke added that his vocals were a little pitchy but the judges can live with that.
Effie was up next with a high-energy performance of "Barracuda" by Heart.
After all the judges were on their feet applauding her, Luke admitted, "You're one of the best singers we have. You truly are... you deserve to be here."
Katy added it was a "flawless" performance and the contestant is visibly surrounded with "star dust," meaning she has the makings of a star.
Alyssa sang "Stay" by Rihanna, and she also earned herself a standing ovation from the judging panel.
Luke revealed that Katy has always been Alyssa's biggest cheerleader and champion on the show, but at the same time, the judges won't cut her any slack. Katy just loves Alyssa's tone and said it separates her from the pack. Given Alyssa has found her confidence, Luke and Lionel now consider themselves sold on her.
Marcio was up next, and he took the stage with a heartfelt performance of "Inseparable" by Natalie Cole, which earned himself a standing ovation from the three judges.
Katy was "so impressed" and proud of Marcio, saying he's grown leaps and bounds since the start of the competition. Katy also pointed out that Marcio makes excellent song choices and needs to simply continue trusting and believing in himself. Luke then called Marcio "a survivor," saying he delivered "a world-class performance."
Mara then showed a totally different side of herself with "Run to You" by Whitney Houston.
The judges got on their feet for Mara, and Luke confessed they were all "spellbound" by her. They were so happy to see this stripped down, "raw and beautiful" version of the rocker given she typically exudes this "edgy and rambunctious" personality onstage. Katy noted, however, Mara could sing addresses out of a phonebook and still entertain.
Jurnee then sang "Flashlight" by Jessie J, and she received a standing ovation from Katy, Lionel and Luke for her "effortless" performance.
"You can sing circles around everyone, and I think that she knows it -- in a good way," Katy said of Jurnee's confidence.
But Katy asked Jurnee to blow her away next time, because it's clear to everyone listening that the contestant has the capacity. Lionel said Jurnee is talented beyond her age, but he asked for even more attitude in her performances.
Luke attempted to explain that since Jurnee makes singing look so easy, she almost needs to prove to America that she's working hard and giving the competition her all.
The next performer of the night was Shannon, who sang "All I Ask" by Adele.
Although Shannon earned a standing ovation, Lionel could tell she was concentrating so hard when standing behind the microphone -- a situation he called "the wall."
However, when Shannon took the microphone off the stand, she had a moment. Luke and Katy appreciated how Shannon took her performance to another level by leaving the piano, and Katy called her "a gorgeous goddess."
Ron then closed out the night with a performance of "Dancing On My Own" by Robyn. He also got the judges on their feet.
Luke could feel everything Ron was saying although he doesn't have the best annunciation, and the judge complimented the singer on his best vocal of the season so far from top to bottom of a song.
Lionel expressed how Ron has come so far on the show and he's proving how badly he wants this -- despite the music industry being such a struggle.
Katy added that Ron is intelligent and has such style. She could feel some of his nerves when he sang, however, and Katy just wanted Ron to know that he belongs here. Katy therefore asked Ron to step it up for his subsequent duet song with an all-star.