Cat Massagers: Do They Work, and Can They Really Help Your Kitty? Why Do Some People Naturally Attract Cats? Why do cats (really) purr? There's something soothing about sitting with a purring cat, but do you know the reasons behind that distinctive vibration? It's commonly thought that cats purr when they're happy and content. While Scientists say a cat's purr may do more than just sound comforting Studies suggest the vibrations fall between 25 and 150 Hz, a range linked to relaxation and stress reduction. Some researchers