A firearm (W) is for discharging a projectile such as bullet (B) through a barrel (L). The firearm includes a firing mechanism (F) for firing the bullet through the barrel. The firing mechanism includes a trigger (T) which is operable by the person using the firearm to fire the weapon. A firing pin (P) is operatively connected to the trigger for contacting a cartridge (C) and effecting discharge of the bullet. A safety mechanism (10) is provided to inhibit operation of the firing mechanism. The safety mechanism includes a blocking element (28) movable into and out of contact with the firing mechanism. The blocking element has a first position inhibiting the firing mechanism from discharging the projectile, and a second position at which the firing mechanism is enabled to discharge the projectile. An audio receiver (14) is mounted on the firearm for receiving audio frequency signals such as a word or words spoken by the person using the firearm. An audio recognition unit (18) also mounted on the firearm has an input from the receiver. Received audio signals are directed to the audio recognition unit which includes a processor for processing the received audio frequency signal. If the received signal corresponds to a predetermined audio frequency signal, the blocking element is moved from its inhibiting position to its enabling position.