Hummingbird Heartbeat

Perry told BBC's Newsbeat that her fiancé Russell Brand had an impact on Teenage Dream. Some of the tracks were recorded before the singer met the British comedian, but their relationship impacted on several of the later tracks. She said: "There are some songs on the album inspired by love. There's a song called Hummingbird Heartbeat. He gives me that Hummingbird Heartbeat."

With the exception of insects, hummingbirds while in flight have the highest metabolism of all animals. Their heart rate can reach as high as 1,260 beats per minute.