In the theremin world, generally the left hand is used to control the volume and articulation of each note. Bringing the hand closer to the Volume Antenna (the Loop Antenna) will decrease the volume, until eventually, with the hand close to or inside the loop, there is no sound. Moving the hand further away will increase the volume.
When adjusting the Volume Antenna Range, you are actually setting the rate of volume change caused by your hand motion. That is, if you want finer control of soft attacks and dynamics, you might try a lower (counterclockwise) value for the VOLUME RANGE knob. If you want to
play individual notes cleanly and with a firmer attack, rotate the VOLUME RANGE knob in the clockwise direction.