Understanding the basic concept of vibrato
Everyone wants to vibrate, but let's talk about the basic concept of vibrato before we get into action.
Vibrato, in string instruments, is a repeated motion of rapid pitch bending. I am no historian but I am pretty sure the idea of vibrato on the string instrument came from how singers vibrate their voice. After all, I think the voice is the most primitive, yet the most pure and easiest medium to communicate with one another in music. For most of us, expressing musical feelings by singing comes natural.
Violin is a singing instrument. We are playing the violin but what we are really doing is that we are singing, using the violin as our vocal cord. When you think that way, it is only natural that we strive to imitate what singers do, including how they vibrate.
Pulse in vibrato
Listen to how good opera singers vibrate when they sing. You will notice that they create a pulse in their vibrato, and also the pulse is steady. We should create a pulse when we vibrate on the violin as well. After you learn to create a pulse, how well you can control the pulse becomes an important technique in mastering the vibrato.
Width and rapidity of vibrato
Besides the pulse, we need to be able to control the width and rapidity of the vibrato. Some phrases would require a wide and slow vibrato while others call for a narrow and fast vibrato. We should be able to control the width and rapidity of the vibrato however we want to depending on what is appropriate for the music that we are playing.
Now that we understand the basic concept of the vibrato, let's move onto how to vibrate!