Star Wolves' writing is not the sharpest, so voice acting adds much needed flavor to the experience. The squad based, tactical space sim gameplay, unique as it is, can only carry you so far. Unfortunately, the English version of SW1 has no dialogue voices. The English voices in SW2 are frequenly dreadful to the point of comedic. SW3 is almost entirely silent, even during flight. It is a tragedy for such a unique series of games.

However, here is some information that's not immediately obvious but might make your experience with the game better.

(1) That big DATA.dat (?)(I fogot the extension) file in the DATA folder is just a normal archive of the content of the DATA folder. You can open it with any archival program like 7-Zip. You don't even have to repack it for it to work. In it is a subfolder called LocData that contains all of the games' voices outside of pre-rendered cuscenes.

(2) The Russian and German versions of SW1 are fully voiced and have almost the exact same directory structure and file names as the English version.

(3) The text of the game exists in separate files and is referenced in separate files that do not depend on the voice files.

There are a little known German language patch for SW2 and a better known Russian/English language patch for SW3 out in the wild. They are not official, so you have to Google them yourself if interested. I also discovered that PCGamingWiki has a lot more useful information than just where the saved games are located.

Someday, we may get a Star Wolves game or one like it that has English localization worthy of its great gamplay ideas.