The two enemy guards in the first room have their backs turned to you and remain oblivious to your presence until you attack. If you silently punch the air from the platform behind them, they become alerted to you. However, if you had instead picked up the chainsaw on the left and held it behind their backs, even though the chainsaw makes noise in its idle position, the guards will remain unaware. This inconsistency occurs because idle weapons are typically silent, while attacking weapons make a sound, except for the fist and chainsaw.