We used to think that our cats just responded to low-voiced singing, as if, during those first six weeks of life before they met us, they had been around some drunken men.
So we would sing, "Oh Give Me a Home, Where the Buffalo Roam ..." and "Swing Low, Sweet Chariot" and whatnot, and they would come running and lick our faces and try to stuff their snouts into our open, singing mouths (what we call "snouting").
Today, we sang the yodel from the beginning of "Raising Arizona". This is a very high-pitched song, unlike the other songs.
They went WILD. They jumped on us and licked our faces, as always, but much more quickly after hearing the first notes. They bit (love nibbles) our legs and scalps. They LOVED it.
So I guess they like long notes.