It’s important to realize that as we play these games involving small models of soldiers, tanks, aircraft, and alien monsters, that even though we have likely spent countless hours assembling and painting them, they still will not produce their own sound effects or provide their own locomotion.
Imagine this: you have an unstoppable Imperial Guard force consisting of two units of Rough Riders, painted in customary teal and vermilion. You order them to charge at an enemy unit of Bloodcrushers (which should be an easy fight for a unit boasting an impressive 5+ armor save such as the Rough Riders). Yet, they do not move. The make no sound. Are they ignoring your orders? Are they ignoring the will of the Emperor himself??
Before you produce a pistol and begin executing your models for cowardice and insubordination, remind yourself that no matter how expensive, these models are merely constructs made of painted plastic. Unfortunately, you must move them by hand. On the upside, they will not resist your attempts to move them.
Sound effects are in fact entirely optional. Surprisingly, most tournament regulars do not produce machine gun sounds during the Shooting Phase, or attempt to simulate the rumbling of tank treads or pounding of boots during the movement phase. This somewhat lessens one’s immersion into the simulated battle, as these sounds simply will not produce themselves.