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
Viola of a viola is wrapped around a peg near the scroll and is tuned by turning the peg. Tightening the string raises the pitch; loosening the string lowers the pitch. The A string is normally tuned first, typically to a pitch of 440 Hz or 442 Hz. The other strings are then tuned to it in intervals of perfect fifths, sometimes by bowing two strings simultaneously. Most violas also have "adjusters"—"fine tuners", that make finer changes. These adjust the tension of the string via rotating a small knob at the opposite or tailpiece end of the string. Such tuning is