This is something I fed back to the Voltera team. It is extremely irritating when working with the printer, especially for long periods of time. I provided them with a recording of the whining noises and they informed me that this is the normal sound of the motors being held in place. They also said:
“You can use ALT+R to release the motors after they’ve finished doing what they need to. If you release them before any kind of tool movement you’ll need to re-home the unit as the printer will have no way to know the absolute position of tools.”
Hope this helps a little.