Carrie Underwood's Son, 5½, Did a 'Great Job' Recording 'Little Drummer Boy' on New Album

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Carrie Underwood couldn't be more proud of her son's singing skills.

The Grammy-winning artist appeared on Wednesday's episode of PEOPLE (the TV show!) where she discussed her experience recording the popular tune "Little Drummer Boy" with her son Isaiah, 5½, on her Christmas album My Gift, out now.

"When I first heard it back I was laughing and crying at the same time because it was just this beautiful, pure moment from him," Underwood said of listening to her son's rendition of the song.

"He did such a great job," she continued. "He remembered the lyrics and he sang it with his whole heart."

The mom of two, who shares sons Isaiah and Jacob Bryan, 20 months, with husband Mike Fisher, said her son was so excited in the studio he was "throwing his hands up into the air."

Asked if her eldest son understands that his mom is a famous singer, she said she can "see little lightbulbs coming on."

"It's mainly when other people talk about it to him," she explained. "If we'll be there with a little friend and the friend's mom is like, 'Oooh now this is Carrie Underwood.' "

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Carrie Underwood's 5-Year-Old Son Did a 'Great Job' Recording Little Drummer Boy for New Album

PLUS: See Carrie’s cute reaction to an adorable fan video

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Last month, the country singer, 37, made a virtual appearance on the Today show where she shared similar sentiments about Isaiah's role on her first-ever Christmas album.

"Whenever I think of that song, I picture his face and his personality. That is so him," she told hosts Savannah Guthrie and Craig Melvin. "He would be the kid that would make you something and bring it to you because that's what he had to give you. And that's the whole sentiment behind 'Little Drummer Boy' is bringing what he has to Jesus, which is why I wanted to name the album My Gift."

Underwood said that she helped her son tap into "all his little 5-year-old emotions" to record the song and that she was "the proudest mom in the world" when watching him sing.

"He was just so expressive. When I heard the song back with his sweet little voice on it, I was laughing and crying and just [had] so many emotions," she said. "I'm so proud of him."

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During a recent interview with Radio.com's Katie & Company, Underwood said Isaiah also has his sights set on another holiday: Halloween.

The country singer revealed that her older son wants to dress up as Oogie Boogie, the bug-infested, dice-throwing villain from Disney and Tim Burton's The Nightmare Before Christmas.

But Underwood is "having some trouble finding that costume, only because it's for adults," she said.

"Lord help us if I have to make 'Ooogie Boogie,' " she quipped. "So, we're gonna see. Maybe I'll get a potato-sack-type of situation — a burlap sack. Maybe I can make one out of that, I'm not sure. Wish me luck!"