As an offline campaigner, I have always considered some speech files ridiculous. I didn't like, for example, being yelled at to 'get back to formation' in a middle of a dogfight, so I got rid of these files long time ago. Finally I grew tired of listening to my AI squadron leader recite, in a robot-like voice, vectors and heights every half a minute, as if all of his subordinates were flying under hoods. It's pointless, annoying and totally unrealistic.
So I went to the 'Actor1' folder and removed all the sound files ranging from 0 to 330 (33 of them) as well as 'Height' and 'Vector' files. What a difference! Now after take-off my squadron heads out in complete radio silence - as they should do - and as we near target area, this silence can really become tense, until someone calls out, for example, 'Fighters one o'clock!' and all hell breaks loose Much more realistic and climatic.
Of course I recommend to back up the files before deleting them. Actually, there's no need to delete them, I stored mine in a separate folder inside the 'Actor1' folder.

If you run mods you can have the location added if someone calls for help

What is the name of that mod and were can I find it?

Hi, you can get it HERE SAS