This is one of the Arkonian's civilian devices. Suralon once had several stations and people would often carry portable radios with them, as they apparently loved music.
Colonel Lifeson finds a portable radio on the floor of a small building in Suralon, near an elevator. When he turns it on, all 5 stations are dead and only make varying frequency noises. However, one of them emits a sound so high that it can shatter glass. Lifeson explots this to retrieve the Key's Sun piece.