Tuning the radio will cycle through the sounds but will sometimes cause the same feedback loop from the main radio, causing more zombies to spawn.

Subtitles are recommended for this as well, as the sound is given a number in the captions like “Active Static 1.” Once players locate the three radio signal boosters, they will have to tune the radio to the same signal emitting from the main radio players interacted with previously.

In Sanitorium, they were always at ground level and never upstairs inside the building. Finding them is easy as they emit a loud static, and they are not far from the location of the radio and won’t be located much higher up than it. This sound needs to be played from 3 smaller signal boosters around the main radio. After the horde of zombies has been dispatched, players will get a small greeting from maxis, as well as a sound. Once finding the radio and interacting with it, it will emit a feedback loop, which will spawn a large number of zombies, so be prepared. The locations are different for every map, so I’ve provided an Imgur album made by Reddit User u/TehPurplePanda & GavinIRL#4154 that holds the locations of every radio for players to look at. The location of Maxis’ Radio on Sanitorium

Call of duty mission list