The SoundMod is a collection of extra sounds (mainly weapon sounds) for use with Space Empires IV. Modders can then refer to them in their mods by their names, thus reducing the need for custom sounds to be included with every mod. Modders can simply use sounds from the mod and request the player to install a certain version of the SoundMod.
The SoundMod can be downloaded here: 
To install the SoundMod, simply download the rar file and extract it into your SE4/Sounds folder. (A good shareware rar extractor is here: ) Do NOT create a separate mod directory for the SoundMod; otherwise other mods will not be able to access its sounds, defeating the purpose of the whole thing!
When a SoundMod is inevitably created for SE5, it is likely that it will not contain copyrighted sounds, in case of a rerelease of the game, so that the SoundMod for SE5 can be included on the rerelease CD, as this prevented SE4's SoundMod from being included on the Deluxe CD.