XNA 4.0 Game Development by Example Beginner's Guide

Sound effects

Sound effects add a level of feedback to your game that, when missing, will be very noticeable to players. Even in situations where sound effects are not realistic (you would not actually hear explosions in space), their absence would feel wrong while playing.

Generating and finding sound effects

There are a number of sound effects freely available on the web that can be tracked down with a little searching. Locating truly royalty free sound effects is a bit harder. Most of the sound effects archives on the web are not the actual originators of the sound files, so their true licensing requirements may be difficult to track down.

You can always record your own effects if you have a way to simulate sounds. In the case of Asteroid Belt ...