Every cello has a "wolf tone" that triggers unwanted resonances in the cello body.  Those dissonant overtones cause one-note, often the low F or F♯, to oscillate loudly like the howling of a wolf. The wolf tone is not a sign of an inferior instrument. In fact, the better the cello, the more pronounced the wolf tone! Better cellos have more resonant bodies that amplify every aspect of the notes, even the painful ones.  A luthier can minimize your cello's wolf note by placing wolf tone eliminators on the fingerboard or behind the bridge on the string.