We need to develop a variety of vibrato actions, as can be seen by viewing some of the high quality violin-playing on YouTube.
In any case, both arm and hand vibrato benefit from a balanced whole body and an upper arm that is available to passsively respond to whichever vibrato action is used.
This exercise helps develop the passive upper arm response firstly in the banjo position (an easy place to observe and develop the motion) and then in violin-playing position.
SEE
Vibrato - Introduction
- for arm, hand, finger vibrato and which to teach first
Bibliography
- for Paul Rolland and Sheila Nelson
...
