7's Nancy Chen reveals 'The Voice' judges' secrets

UNDATED (WHDH) -- They're four of the biggest stars in music: Christina Aguilera, Adam Levine, Blake Shelton and Cee Lo Green. We know them for their songs and styles, but wow about their secrets?

Cee Lo's famous for his crazy hair, clothes and companions but it turns out it's what you can't see on him that's also remarkable.

“He wears a lot of cologne,” said one contestant.

As part of Maroon 5, Adam Levine is an international superstar with the risqué music videos and supermodel girlfriends to match -- but apparently, not the ego.

Melanie Martinez says Adam talked about his own weaknesses to help her.

“He just told me to stick to being myself. He says he's a soft singer too, where he can't hit all these big notes,” said Martinez.

And then there's Christina Aguilera, everyone's favorite diva who has a recording studio at home for any time inspiration hits. Dez Duron told 7News he and the rest of her team got to check it out firsthand.

“It was incredible. We hung out in her studio, it was just us five, her and the engineer, no cameras. No anything,” said Duron.

Still, with all this star power, you never know what might happen especially with a prankster like Blake Shelton around.

“Everything that comes out of his mouth surprises us,” said one contestant.