Ethan finds a Sonic Emitter
Sonic Emitters are mysterious devices linked to the increase in crime, and are exclusive to Condemned 2: Bloodshot. They are found throughout Metro City, most likely planted by the Oro. They presumably work similarly to their "voices," in that they use sound waves to influence victims' brains, causing them to become uncontrollably violent. Emitters can be found using the Spectrometer, and can be destroyed with any attack, although ranged attacks are recommended since Ethan takes damage when he approaches them. One way to tell if a sonic emitter is nearby is by a large amount of dead birds.
In Condemned: Criminal Origins, there are no Sonic Emitters visible, but many dead birds can be found around the city in various levels of decay. It is revealed early on in Condemned 2 that despite being attracted to sonic wavelengths, their small brains cannot handle them, causing their heads to explode. In Condemned 2: Bloodshot, the number of Sonic Emitters destroyed during the course of a level directly affects the rank given at the end of the level.
Condemned 2: Bloodshot Multiplayer[]
Sonic emitters are available in Crime Scene Mode in Condemned 2's multiplayer component. Players on The Influenced side can select a sonic emitter as a starting weapon. Placing a sonic emitter near evidence scrambles the SCU's spectrometers, making it more difficult for them to find the evidence.