The S03 is equipped with two Velocity Sensitivity parameters, 'Velocity Curve' and 'Fixed Velocity'.
The 'Velocity Curve' settings determine the sound output of the keyboard based on the playing style. For example, a player that has a soft touch may choose the 'SOFT1' setting to boost the sound output. The sound output is not fixed but based on a curve that shapes the sound output.
The 'Fixed Velocity' setting disables the effect of the 'Velocity Curve' setting and applies a fixed sound output. In this case, it does not matter how hard or soft the keys are played. The sound output is fixed at a selected level.

Velocity Curve:

1) Press the [UTILITY] button.
2) Press the button until the screen displays 'Velocity Curve'.
3) Press [INC/YES] or [DEC/NO] to set the Velocity Curve to the desired type, 'NORM', 'SOFT1', SOFT2', 'EASY', 'WIDE' and 'HARD'.
4) Press the [ENTER] button.
Fixed Velocity:

1) Press the [UTILITY] button.
2) Press the button until the screen displays 'Velocity Curve'.
3) Press the button. The screen will display 'Fixed Velocity = xx'.
4) Press [INC/YES] or [DEC/NO] to set the Fixed Velocity to the desired level, 1 - 127 or OFF.
5) Press the [ENTER] button.

Reference: Owners Manual, p. 90 - 91