With the whole family of stringed instruments the vibrato technique can be used
to make variations in the tone. The variation is actually one of pitch, caused by
moving the left hand finger backward and forwards in line with the string. The fingertip
does not lose contact, nor does the thumb. The hand is simply made to oscillate
sideways along the same plane as the strings.
Put the second finger on the E at the fifth fret of the second string. Play a
rest stroke over the sound hole, and try oscillating the hand as described above.
Remember to keep both thumb and finger in contact. Try the note with and without
vibrato and notice the difference. Then experiment with notes all over the guitar.
You will find the vibrato most effective above the fourth fret.
Below the fourth fret, the sideways vibrato is sometimes used, where the string
is pushed back and forth on the fingerboard at right angles to the plane of the
strings. This has to be done with subtlety so as not to sound like a blues bend,
and is in fact rarely used.
The vibrato is rarely notated, the abbreviation “vib.” being the most used indication.
The sounds that most tend to amaze the listener are those produced by a really
well-executed scale, arpeggio or tremolo passage.