A sound is a short piece of AIFF audio. Sounds could play when firing a weapon, when a ship explodes, when a button is clicked, or any number of other situations.
Maybe.
If you’re adding new weapons, you’ll probably want to add new sounds for them. Also, other actions may benefit from sounds: an object’s arrival or destruction, for example.
If none of that applies, you don’t need to add any sounds.
Sounds are in the sounds directory and have a .aiff file extension.
By convention, the name for a sound starts with a three-letter directory. Sounds that correspond to an object in some straightforward way share their name. In the factory scenario, for example, most of the sounds associated with weapons are named dev/(weapon), and the sounds associated with explosions are in sfx/explosion/(kind). Beeps and other sounds used by the game’s user interface are in gui.
Antares supports AIFF sounds.