Static Angels

Throughout season 2, George Vickers Jr. is often shown listening to radio static. When asked about it, he claims that he can hear angels' singing hidden in the noise. It is implied that he started doing this to drown out the sound of his parents arguing. When Karina Hernandez babysits George Jr., she humors him by letting him play radio static for her. She is unsettled when she, too, is able to hear otherworldly voices singing. When Police Officer Ángel Hernandez shows up on the scene of the Applebee's Massacre, he attempts to call for backup but the only sound he can receive on his police radio is this same otherworldly singing. The source of these voices is never explained.

Theories
Because the common factor to these two Static Angel occurrences is George Vickers (as the father of George Jr. and the instigator of the Applebee's Massacre), there is speculation that George Vickers broadcasts the signal somehow. George Jr. references hearing the voices before George Vickers becomes Subject 93 however, and there's no indication that George Vickers has any supernatural abilities before his participation in the Ambrosia Project. Another theory is that the voices are caused by participants in the Ambrosia Project more generally and that the earlier voices George Jr. heard were caused by the numerous participants prior to George Vickers who died in the process. Yet another theory is that the voices are cause the Maudlings, perhaps by their attempts to communicate with their dimension of origin, and that the seeming relationship to George Vickers is coincidental.