Clockwise from left: Alanis Morissette, Will.i.am, Nick Lachey, Grimes; Greg Gayne/FOX

Nick Lachey is coming to terms with the fact that he's approaching his 50th birthday. The 98 Degrees singer opened up to The New York Post about what made him start reevaluating his age.

"I've never felt older in my life than sitting next to Grimes on a judging panel," the 47-year-old laughed in reference to his new reality singing competition series, Alter Ego.

In addition to the 14-year age difference separating him and the 33-year-old singer, he says they are both operating on completely different mindsets. "The way her mind operates and the things that she understands, I don’t even begin to grasp how those things are working," he explained.

Grimes is in a relationship with tech entrepreneur Elon Musk, with whom she shares one-year-old son, X Æ A-Xii, which is pronounced X-Ash-A-Twelve.

Also sitting with Grimes and Nick on the Alter Ego judging panel are will.i.am and Alanis Morissette.  Lachey says the different backgrounds represented at the judges' table is exactly what makes the singing competition stand out.

"We are all so different," said Nick. "We come from different backgrounds.  Will is also very into tech. I think Alanis and I are a little bit more of your kind of straight-ahead, not-really-understanding-what’s-going-on type performers...But I think what I do understand and really recognize is true talent — and that’s what cuts through in the performances."

Alter Ego, which features competitors wearing motion-capture suits and singing backstage as their digital avatar performs in their stead on stage, debuted Wednesday on Fox. Another episode airs tonight at 9 p.m. ET.

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