A light, fast LH tremolo allows us to hear the harmonic clearly, and at the same time to hear the presence of the open string underneath. This technique makes the harmonic more stable. (Knox)
The quartertone trills usually require a special way of placing the finger, depending on the size of the finger. Placing the main part of the fingertip on the fingerboard beside the string and just touching the string with the tip of finger is probably most satisfactory. (Knox)
