Minecarts that are stationary but touching make nonstop rolling sounds if they are oriented north/south. However if you turn it 90 degrees so the ends face west and east, touching minecarts are silent.

I am building an item sorter that uses hopper minecarts on angled rails. The sorters are one block wide and lined up side by side. The sections that are oriented west/east make non stop 24/7 rolling sounds while the sections facing west/east are perfectly silent.

The section is facing west and makes the sounds