Rita has joined Sir Tom, Will and Ricky Wilson in the spinning red chairs for the fourth series of the BBC One singing show, which starts in January 2015.
The Welsh crooner admitted that Black Eyed Peas star Will has even been told off for being distracted with his handset on set.
“They’re always (makes phone motions) whereas Ricky and I are not doing a lot of that,” he said backstage at the BBC Music Awards.
“We’re concentrating on what’s happening on the stage.
“I think Will gets ticked off about it from time to time.”
Sir Tom said Rita has already forged a bond with Will.
“She is closest to Will because they’ve worked together,” he added.
“Rita is great – she’s fresh and she’s what is happening now. She fills that seat very well,” he said.
The knock-out stages have been filmed, and Sir Tom revealed there is “a good mix of voices. I don’t think there are any two singers who are similar”.
The 74-year-old singer also said it feels “natural” to return to his spinning chair.
“It feels very natural to me to do it again. It’s my fourth time now… The more I do it, the more natural it feels,” he continued.
“At the start, it was all new to all of us but that was exciting. It was the first time I had ever been a judge and it was a new thing for me. I’m enjoying doing it. The thing I like about the show is there are four entertainers who are coaches, so we know what it’s like to be on that stage.”
The Voice, BBC1, January 2015.