I think everyone would agree that the voice acting in Aquanox is atrocious. Here is a quick and dirty way to mod the game so that the dialog is silenced. Since the game is already subtitled, it does not affect normal gameplay. And muting the dialog will actually make the game MUCH more tolerable.

You will need:
unmpak (http://djdeadmind.pithed.org/aquanox/dl/generic/unmpak.zip)
mp3gain (http://mp3gain.sourceforge.net/download.php)
About 250MB of extra space.

Essentially, I used mp3gain to lower the volume of the dialog to inaudible levels.

Here is a rough step-by-step guide. (A little knowledge of using command-line is required):

1. Extract unmpak. Locate your Aquanox directory (usually C:\Program Files\GOG.com\AquaNox). Copy Aquanox\dat\pak\aquanox1.pak to the unmpak directory.

2. Open a command line window (Start Menu->run->cmd). Go to the unmpak directory, and input:
unmpak -m aquanox1.pak
This creates a keyfile. I don't know what that does, but you need it.

3. Type in:
unmpak aquanox1.pak
This extracts all files packed in aquanox1. There should be a new directory called \sfx. This contains all the voices/music/boom-boom of the game.

4. You only need the folder \sfx\sample\e. You can delete the rest.

5. Install mp3gain. Run mp3gainGUI.

6. In mp3gain, press "Add Folder". Add "\sfx\sample\e". This adds all dialog files to mp3gain.

7. Press Ctrl-O to change "constant gain". Drag the slider to far-left (-12.0 dB). Press Ok. Wait a few minutes.

8. By now the volume of the dialog is significantly decreased. Redo step 7 again to reduce the volume to almost inaudible level. You only to re-apply constant gain twice to make it completely silent.

9. Copy the \sfx directory into your Aquanox directory. Done!

Now enjoy the voice-less Aquanox!

Thank you so much!

I was stuck, trying to find a way to re-pack the extracted files, until I saw this post. Now I know how things work so that I can replace all the dialogues with German vocals. What a relief!

You have my appreciation.