The core issue is not whether the sound scares someone, only if you make a deliberate show of it to intimidate an opponent.
If I were armed and facing you and your shotgun, I would shoot you while you are futzing around with it. In your house, assuming I'm not the 'all burglars are cowards' type, if I hear a big rack, I might leave or for the tactical advantage, I would fire a series of shots at the location of the rack. That might scare you.
So, is it a show? For the LEO, facing a dude, who probably doesn't have a gun out, is misbehaving in a nonlethal threat manner - sure rack away for the Clint Eastwoodiness of it.
As I said before, when you pick up the gun, you rack it and you should be behind cover if you are able. If it is heard then and has a positive effect - goody.
Otherwise, if I want sound effects - I'll play the 1812 Overture with cannons.