They definantly hear it, but every deer reacts differently at different times, I have dropped a doe with 5 others near her in a field and they all just froze and looked around for 30-40 seconds and went right back to feeding, I have shot deer, missed them and had them stand there, I have also shot at deer and had them haul booty! Usually a deer wants to know where the danger is before they run, if they don' t know where the shot came from sometimes they will just stand there, hunting with a smoke pole you can bet money they will be running the second they see the smoke from the shot.