Vibrato is one of the most important colours in our tonal palette and we need to develop a range of vibratos to suit different musical characters. To begin we need to develop a consistent even vibrato action with average speed and width (this is often said to be 6.5 full vibrato cycles per second and a quarter-tone wide). However once this is reliably established you need to develop the ability to vary the two variables of speed and width.
Use a wide vibrato with an average speed and then without intentionally changing the speed gradually narrow the distance of the vibrato action. Close your eyes to concentrate on the difference in sound between the wider and narrower vibrato actions.
SEE
Vibrato - Harmonic Touch
Bibliography
- for The Teaching of Action in String Playing by Rolland, ch.15
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