Harris: My out of body experience
The 28-year-old DJ and music producer duetted with the singer when she headlined the Californian music festival earlier this year.
Calvin told The Guardian: "Some pop moments are more like outer body experiences... I remember playing We Found Love with Rihanna at Coachella. There was a sea of camera-phone lights and I was up on this big riser, taking it all in.
"Then I looked down and saw Katy Perry crowd-surfing. I thought: 'OK, this will definitely never happen again, so let's remember this for all time.'"
He said: "Female vocals make for the best dance tracks.
"They're always at the perfect frequency to play in a club. A good, soaring, high-mid female vocal bounces off the walls nicely, and it doesn't interfere with the bass or drumbeat. It's basic science. A man's voice is likely to interfere with the bassline which is why you don't hear many classic dance tracks with a male lead."