The Sonic Boom is a high-powered, "experimental", sonic frequency device developed by STAG. Like other STAG weaponry, it is designed to shoot out highly concentrated bursts of energy and not bullets, but unlike other STAG weaponry, this weapon concentrates the energy into focused, sonic frequency waves which are so powerful, they can be used to move heavy objects and open locked doors.
The Sonic Boom is obtained during the mission "Air Steelport", and then featured in "Zombie Attack" and "Three Way". Using it is required to complete all three missions.
It has to be charged up before firing. When fully charged and used on people, the weapon has the same effect as the Apoca-Fist. Incompletely charged, it flings enemies backwards and causes them to ragdoll. When fully charged, the Sonic Boom gibs just about anything, including the bodies of people who are already dead. The Sonic Boom can also be used to move vehicles. A charged shot used on a vehicle filled with people often gibs everyone inside as well as damage the vehicle, which is useful against the police or gang members when they arrive on the scene. It is also quite handy for pushing water vehicles back into or out of the water, or turning a flipped car back onto its wheels before it blows up.
Very good when tackling hordes of enemies (e.g. zombies)
Does not damage Homies much or cause them to become hostile.
Cons
Last Special weapon unlocked.
Shortest range of any Special weapon.
Range is difficult to judge.
Difficult to determine damage if not fully charged; the only way to determine if an enemy has survived a blast is to wait to see if they get back up again.
Trivia[]
The Sonic Boom throws another player in co-op even if friendly fire is set to off.
The Sonic Boom somewhat resembles the Gravity gun in Half-Life 2, also sharing a similar function (moving heavy objects) and similar sound effects. The weapon also resembles some of the alien weapons from District 9, as well as the bloody result from their usage. The weapon also closely resembles the Spartan laser from the Halo series in both design and the need to charge it up before using it.
Sonic Boom is also the name of an attack of Guile in the Street Fighter series. In the Whored Mode there is a wave named "Be Guiled!" with description "Where's Charlie you need him". In Street Fighter, Charlie is Guile's best friend and senior officer in the USAF, who taught Guile how to use the move.
If a Sonic Boom is spawned during the mission I'm Free - Free Falling using cheats, the room in the cut scene can be entered and the plane can be escaped without triggering the skydiving segment.
It is the only weapon that can open doors.
During the "Save Shaundi" optional segment in Three Way, the Sonic Boom must be used to remove the bombs from the statue.
The weapon's effects are somewhat similar to the Thundergun from Call of Duty: Black Ops.
It is one of several weapons in the game which can be charged, others being the Cyber Buster, and the Laser Beam.
The Sonic Boom does not generate hate from Homies and a fully charged blast does not send them ragdolling, or injure them. This makes this weapon safe to use around Homies without fear of knocking them out or causing them to become hostile.
During the Save Shaundi ending to Three Way, the Sonic Boom can break Kia's grip from Shaundi, allowing her to be recruited in order to fight Kia, and also allows easy hits on Kia without having to worry about hitting Shaundi.
The Sonic Boom resembles the Spartan Laser from the Halo series. The only difference is the sonic boom can be used uncharged and charged, while the Spartan Laser needs charge completely to shoot.
When aiming, the "antennas" move.
Although ammunition for this weapon is infinite, endless ammunition can be purchased for it at Friendly Fire, which has no effect.