Violin where a stopped note sounds a unison or octave with another (open) string, causing it to resonate sympathetically. Students often use these ringing tones to check the intonation of the stopped note by seeing if it is harmonious with the open string. For example, when playing the stopped pitch "A" on the G string, the violinist could play the open D string at the same time, to check the intonation of the stopped "A". If the "A" is in tune, the "A" and the open D string should produce a harmonious perfect fourth. Violins are tuned in perfect fifths, like
Guitar tunings tuned fifth string can provide a reference to tune the remaining strings by ear. Tuning forks which provide the pitch of the high E string (329.63 Hz) are also common. The guitar is conventionally an equal-tempered instrument. The frets are positioned logarithmically, creating equally-tempered pitches along each string. However, guitarists who tune by ear will typically tune “clean” so that dissonant beating between particular strings is minimized. In this way, open intervals can be more consonant. This is known as just intonation, which is at variance with equal temperament. When the guitar is tuned in this way, open tunings theoretically