Every cello on the planet has a wolf tone; they are as much a part of a cello as a belly button is a part of its player. If you can’t hear it, it’s either because it’s on a pitch you don’t play, or because there’s a wolf damper glued on the inside of the cello. The wolf is caused by a change in phase between the vibration of the string and that of the body of the instrument—it’s like breaking the sound barrier. Every instrument has a resonant pitch which, as it turns out, is that of the wolf tone. Below that pitch, the instrument and the string vibrate in phase. Above that pitch, they move in counter-phase. The wolf is the acoustic turbulence when the phase is in transition. Since the wolf is produced by the vibration of the cello, the more it vibrates, the more pronounced the wolf.