Do pets really know their own names?

I'd have to say that pets definitely know their own name, the intelligent ones anyway. Even if I were to call to my cat in a calm, sweet voice but saying any other word other than her name she'd flat out ignore me. I think it's a combination of tone and the name, otherwise I think our pets would come running to us every time we said a word that sounded the same as their name in a sweet tone.