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 tuning and typically lowers the pitch ("drops") of only a single string, more common is the whole instrument and least common is two dropped strings (ie. DADGAD). This is almost always the lowest pitched (E) string on the guitar, although occasionally the A string may be lowered. The Drop D tuning, for example, is common in classical guitar and heavy metal music. For it, the low E string is tuned down one whole step, to a low D, and the rest of the guitar remains in standard tuning. This creates an 'open power chord' (three-note fifth) with the low three