It entirely depends on what your speech mod changes.
As Hunter has said, there are 9 different voices but within these 9 folders there are speech files for (IIRC) Loud, Normal & Whisper versions of every file.
I think that if your mod only accounts for one set of these then you may or may not hear them ingame. However, if you replace the originals with your version, I think you might hear the same voice all the time.
It might be trial & error time. Make your pack resemble speech folder 1 & enable it. Then start your game and see which officer uses them.
Good Luck
