Normally, enemies on Death Sentence have a radio voice filter. With this mod, they will have the same voices as 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.)
heavy_swat_sniper: Includes ZEAL Marksmen
This mod was only tested in singleplayer. It may or may not work online.