nothing on the sheet music that compels violinists to add vibrato. This can be an obstacle to a classically trained violinist wishing to play in a style that uses little or no vibrato at all, such as baroque music played in period style and many traditional fiddling styles. Vibrato can be produced by a proper combination of finger, wrist and arm motions. One method, called hand vibrato (or wrist vibrato), involves rocking the hand back at the wrist to achieve oscillation. In contrast, another method, arm vibrato, modulates the pitch by movement at the elbow. A combination of these techniques allows a player to produce a large variety of tonal effects. The "when" and "what for" and "how much" of violin vibrato are artistic matters of style and taste, with different teachers, music schools and styles of music favouring different styles of vibrato. For example, overdone vibrato may become distracting. In acoustic terms, the interest that vibrato adds to the sound has to do with the way that the overtone mix (or tone color, or timbre) and the directional pattern of sound projection change with changes in pitch. By "pointing" the sound at different parts of the room in a rhythmic way, vibrato adds a "shimmer" or "liveliness" to the sound of a well-made violin. Vibrato is, in a large part, left to the discretion of the violinist. Different types of vibrato will bring different moods to the piece, and the varying degrees and styles of vibrato are often characteristics that stand out in well-known violinists. Vibrato trill A vibrato-like motion can sometimes be used to create a fast trill effect. To execute this effect, the finger above the finger stopping the note is placed very slightly off the string (firmly pressed against the finger stopping the string) and a vibrato motion is implemented. The second finger will lightly touch the string above the lower finger with each oscillation, causing the pitch to oscillate in a fashion that sounds like a mix between wide vibrato and a very fast trill. This gives a less defined transition between the higher and lower note, and is usually implemented by interpretative choice. This trill technique only works well for semi-tonal trills or trills in high positions (where the distance between notes is lessened), as it requires the trilling finger and the finger below it to be touching, limiting the distance that can be