U.S. Air Force Master Sgt. John Sperling, the 354th Communications Squadron NCO in-charge of radio frequency transmission systems, adjusts the tone of a Giant Voice radio May 14, 2015, at Eielson Air Force Base, Alaska. The Giant Voice system is the most direct and fastest means for Command Post to communicate emergencies to the base. (U.S. Air Force photo by Senior Airman Ashley Nicole Taylor/Released)