I am not an expert, but I assume that the amount and type noise you hear when the motor is not moving depends on the current and the exact position in which the coils have to keep the axis balanced in between the full-step positions. But even when there is no noise, as long as the stepper motor is enabled, there will always flow current at least in one coil.
The stepper motors need the current when not moving to keep the position at the current position. You will note that if you try moving the motor by hand, it takes a lot of force while the motor is enabled. If you cut off the current altogether, the motor axis will jump to the nearest full step position, but it now can be easily moved by hand. You can disable the motors between moves in the firmware (macros DISABLE_[XYZ] in Marlin) - I use that sometimes, but only for the Z-axis (after making sure that my layer height is a multiple of the full-step distance).
The stepper motors need the current when not moving to keep the position at the current position. You will note that if you try moving the motor by hand, it takes a lot of force while the motor is enabled. If you cut off the current altogether, the motor axis will jump to the nearest full step position, but it now can be easily moved by hand. You can disable the motors between moves in the firmware (macros DISABLE_[XYZ] in Marlin) - I use that sometimes, but only for the Z-axis (after making sure that my layer height is a multiple of the full-step distance).