Touching minecarts make nonstop rolling sounds, when facing north or south, but are completely silent when facing west or east

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