Lorenzo is, by far, the smartest dog I've ever met. He's very curious and whenever he hears music, or when I'm working away at the computer, he likes to play the guitar. How? He taps it with his nose until it moves enough to make a sound and repeats this a couple times until he's satisfied that he's contributed enough to the music... LOL
Lorenzo also has a keen ear for music and intonation – whenever I've had rehearsals at my house, he just has to be around (like a supervisor). At first, he just stands in the middle and looks around at what's going on, but then he'll quickly turn his head and stare people down when they play something wrong, or if they play very "outside" sounding jazz solos. I don't know how he can tell, but other musicians have tested him on it too – I now have no doubt about it that he somehow knows. But how?
Lorenzo's musical abilities have been developing over time – he knows with certainty what he does and doesn't like, and somehow, he can always tell when someone makes a mistake. I can't play the guitar anymore without having him sit next to me and judge me the whole time!