On Death Sentence, enemies have a radio voice filter. With this mod, they will have it on lower difficulties.
Below is a list of tweak_data tables that this mod affects and which enemies are in each group. You can go into the charactertweakdata file and delete the group you don't want affected.
Spoiler!
swat: Includes SWAT and ZEAL lights as well as FBI agents with balaclavas (also known as HRTs)
heavy_swat: Includes SWAT and ZEAL heavies
fbi_swat: Includes FBI lights
fbi_heavy_swat: Includes FBI and GenSec heavies
city_swat: Includes GenSec lights as well as guard Murkies (from Shadow Raid, Slaughterhouse, etc.)
Notes
This mod primarily affects the America and Murkywater factions.
This mod may not work unless you are the host.
Regular security guards, Marshals and other non-SWAT enemies are not affected.