Hard sound rifle

A Hard Sound Rifle is a Human-made sonic weapon. As it utilizes concentrated sound waves instead of a solid projectile, a hard-sound rifle leaves no residue or powder burns and causes little noticeable external damage to the intended target, making the weapon virtually untraceable in forensic investigations. A preferred and favored weapon used for assassinations by the Office of Naval Intelligence, they are sometimes (illegally) purchased by civilians for less malevolent means.

Although sonic weaponry does not appear in Halo: Combat Evolved, Halo 2, or Halo 3, it is mentioned prominently in I Love Bees. When an ONI assassin disguised as a homeless man was sent to kill Rani Sobeck for her investigation into a covert evacuation of the human colony of Troy, a protective detail dispatched by Colonel Herzog eliminated the operative through use of a hard-sound rifle. Having fallen off the roof to the street below, local authorities dismissed the death as an accident resulting from use of alcohol or drugs.