Where does wolf collide?

In musical acoustics, the wolf tone is an unstable, stuttering note on a bowed string instrument (most notoriously the cello) that occurs when a played pitch nearly coincides with a strong resonance of the instrument's body, so the string and body exchange energy and beat against each other instead of sounding a steady tone. C. V. Raman's 1916 On the "wolf-note" in bowed stringed instruments gave the first mechanical account of the effect, and Neville Fletcher and Thomas Rossing's The physics of musical instruments frames it in terms of body resonance. The referent is an acoustic instability from a near-coincidence of string and body resonances, and it shares the word with a tuning interval and with the animal but nothing else.[1][2]

Unit

The beating instability near a coincidence of string and body resonance

Recovery means

Not applicable

Measured by

Characterised by the beat frequency and the proximity of the played pitch to the body's main resonance; suppressed with a wolf eliminator

In the theory of tuning and temperament, the wolf is an interval left so far from its pure form that it sounds harsh and howling, classically the one much-widened or narrowed fifth that absorbs the leftover comma in a meantone or Pythagorean tuning, so that most keys sound sweet but the keys using that interval are unusable. J. Murray Barbour's Tuning and temperament: A historical survey catalogues how different temperaments place and manage this wolf. The referent is a specific mistuned interval produced by a tuning scheme, not an acoustic instability of an instrument's body and certainly not an animal, joined to them only by the howling sound that gives all three the name.[3]

Unit

The deviation of a tempered interval from its pure ratio

Recovery means

Not applicable

Measured by

Quantified in cents as the interval's departure from just intonation, concentrated into the wolf by the temperament