High Quality Content by WIKIPEDIA articles! A wolf tone, or simply a "wolf", is produced when a played note matches the natural resonating frequency of the body of a musical instrument, producing a sustaining sympathetic artificial overtone that amplifies and expands the frequencies of the original note, frequently accompanied by an oscillating beating (due to the uneven frequencies between the natural note and artificial overtone) which may be likened to the howling of the animal. A similar phenomenon is the wolf interval, usually between E flat and G sharp, of the various non-circulating temperaments.