Scratch tone and air-noise are both varieties of non-pitched sounds that we can create with a muted string. While there are many subtle gradations possible, a basic non-pitch sound is not too difficult to achieve — just lightly drape a few fingers over the strings in order to obstruct its normal vibration. Heavy bow pressure and slow bow speed will create a scratch tone with no discernible pitch:
Very light flautando bowing will get a subtle airy noise that hints at a pitch but does not have tone:
A few tips:
- Do not press the fingers down, as you do not want to fully stop the string.
- Use a few fingers, if not the whole hand, so that you don’t accidentally activate a harmonic node.
- Experiment with the subtle variations in sound that are possible. In addition to changing the bow speed, pressure, and contact point, you can try placing your left hand on different spots on the string
- Because these sounds are quite subtle in their differences, it’s always best to ask the composer what he or she wants.
Read on to the final page in this section to see Pressure Techniques in the Repertoire.