Both singers need frequent vocal rest – Mayer has needed it critically due to his serious vocal-cord problems – and so, quite often, their home can be oddly quiet.
"I understood that he couldn't talk, and the only way he could communicate was through an iPad," Perry, 29, says in an interview airing Friday on The Ellen DeGeneres Show. "Some days I have to go on complete vocal rest, like no anything, no whispering. Whispering is actually really bad. There's just a lot of silence in our house most of the time."
When DeGeneres suggests playing Pictionary, Perry comes back with a better idea: "We should just learn sign language," she says.
Later, Mayer, 36, surprises Perry on the set. And after Perry makes a joke about Kanye West's "Bound 2" video – saying Kim Kardashian's hair was blowing the wrong way – Mayer jokes that her humor is all the talking they need at home.
"This is why voice rest is just fine," he says. "You get these chestnuts."
Meanwhile, Mayer's new duet with Perry, "Who You Love," is about persevering through the ups and downs of a relationship. And Perry says she's glad she did that with Mayer through their time together.
"I think when two people are involved, someone other than yourself, you have to figure out a compromise in a good way. And there's a lot of respect," she says.
"We have a lot of fun. You know, we have music as an understanding and love between each other, and we connect, and you know it's like he understands what I do because he does the same thing. And so after a long day, if it's been tough, I don't really have to go into it. He just gets it. You know, so it's nice with that understanding."