Have any of you guys ever wanted to the “Preview Sound” button working? It’s rather easy. In short, all you have to do is extract all of the audio files out of the BIG files & world builder will reccanize them & will preview the sound! If you know how to do that, then you don’t need to read the step by step instructions below.
Please take note that following the Command & Conquer Generals Instructions, will add 500 MB’s to your computer. When you extract the audio files, it basically makes copies of all the audio files.

Command & Conquer Generals Instructions:
1) First you need a BIG-File- program like BigPop. You can download it here.
2) Now go to the game directory. (“C:\Program Files\EA Games\Command and Conquer Generals” Unless you specified a diffent loction for it while installing.)
3) Open up the “SpeechEnglish.big” file in FinalBIG.
4) Click on the “Edit” menu & click on “Extract all”
5) In the “Browse for folder” window, select the game directory folder. (To do this, click on the “+” to the left of “Local Disc (C:)”, “Program Files”, & Then “EA Games”. Unless you specified a different location for the game directory, as I said above.)
6) Now select (Don’t open) “Command and Conquer Generals” & click on “OK”. (On my computer, it took about a minute & a half to complete the extraction.)
7) Repeat the steps above only with the “Speech.big”. But some of them might not work though. Probably because EA Games intended some clips to play, but disited against it latter.
The sound effect files are split up into two files, one with the voices & the other with the sounds. You’ll need to repeat the steps above extracting these two just as you did with the “SpeechEnglish.big”. They’re called “AudioEnglish.big” & “Audio.big”.
That’s it!

Source: cnclabs.com