When a group moves in stealth or danger mode, the AI units call out "Go", "I'm covering", "cover me", etc, etc. They do this without using radios.
OBS:
If the speaker is distant from the player/camera, the audio becomes distorted. The further the speaker, the more distortion.
Radio based communication and other sound effects are not affected.
EXP:
If the speaker is distant from the player/camera, the audio should become quieter. There should be no distortion.