From left: Noah, Tish and Miley Cyrus
06/14/2013 AT 07:15 PM EDT
Hours after the news broke of her parents' divorce
, Miley Cyrus
was on the air in Chicago promoting her new single, "We Can't Stop," from an upcoming, still-untitled pop album.
"She was in a really good mood, and she was talking about how she worked with Snoop Dogg on her album, and we asked her about her hair and her new look," Showbiz Shelly
, entertainment reporter for B96 Radio
in Chicago, tells PEOPLE of the Friday broadcast.
But after the interview, Cyrus – whose father, Billy Ray Cyrus, and mother, Tish Cyrus, announced their split to PEOPLE late Thursday – opened up about more personal matters, including concern for her little sister, Noah.
When asked how she's doing in the wake of the divorce news, Shelly says Cyrus, 20, said, "Oh, I'm fine. I'm okay."
Shelly says she also said her parents' divorce after 19 years of marriage won't be that noticeable for the singer because of her busy travel schedule.
"I'm much more concerned for my sister [Noah]. She's 13," Cyrus said, according to Shelly, whose real name is Michelle Menaker.
On Friday Noah Tweeted
, "Please pray for me and my family."
(Tish is requesting primary physical and legal custody of Noah with visitation for Billy Ray, according to the documents filed Thursday in L.A. Superior Court.)
But Miley was upbeat during her time at B96 in Chicago, where she's introducing Macklemore and Ryan Lewis at the B96 Pepsi Summer Bash
"With everything that's happened, she was very nice and really didn’t seem affected. If she was, she was covering it up really well," Shelly tells PEOPLE. "We really enjoyed having her."
Reporting by JEFF NELSON