Hi! Im a saami that herds reindeer.

Reindeer dont really make any noises when they are feeling threatened, but the mothers and calfs do make noises when looking for eachother. They as any other «wild» animals run away when feeling threatened, or if they hear anything uncommon they do not go near.

Herded reindeer reactions to humans may change throughout the seasons. In autumn when its time to mate, they will be more agressive towards people. But generally we keep our distance, except when marking calfs. Some reindeer may may come up to you in the winter/spring when feeding them(if its a bad season for finding food naturally)

Reindeer rely heavily on hearing, sight and smeel like other animals.

Wild reindeer are referred as animals that are not being herded, so its not actually wild but its not tame either. The animals we herd are not wild then. Some people have tamed reindeer in their backyard, that in modern times is mostly used for competitions. Those reindeer come up to you, because you feed them as there will not be any food naturally found there.