Are you referring to the terror_meter? If so, that's a setting located in the game.cfg under Player_General. Change TerrorSound to have a null value, like so.
<Player_General
FOV = "70"
FarClipPlaine = "400"
//...
TerrorSound = ""
/>
You'll need a full conversion though if you want to get rid of that specific thing.
If you want to get rid of the sounds that are made, you should create a new grunt entity and assign it a new name other than servant_grunt.ent, so that the game doesn't load the other.