 A wolf tone is 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 a wolf.A similar phenomenon is the beating produced by a wolf interval, which is usually the interval between E and G of the various non-circulating temperaments.Wolf tones are usually only noticed on bowed instruments, most notably the violin family, since the tones produced are played for much longer periods, and thus are easier to hear.