I'm sure it has come up before on some thread, but my old set of cats (long gone but still missed) Witchy Poo and Shadow, would always yowl along whenever I sang. Like all youse, I couldn't tell if they were joining the chorus or complaining. The last boyfriend's two dogs did, too. Woof along, that is. My current cats are indifferent to singing but decide it's lap time if I want to practice guitar. They're all just individual.

They ALL have always loved the sound of the can opener, however.