The sounds heard on the field of battle are often a determinative element of the amount of fear and panic coursing through a soldiers body. Recreating this in a practice scenario helps soldiers acclimatise their bodies to situations where the noise around them is greater than that of a rock concert.
However, it seems unlikely that the researches can factor in the destabilising force felt by soldiers when hit by ordinance. It often isn’t just the sound but the feeling of having the wind sucked out of you that creates the fear and panic that soldiers are trained to avoid.
Another important element in creating a realistic environment is that soldiers are constantly on the move, so unlike watching a film at a theatre or playing a game the position of the body relative to the sounds is never static. Hence, the researchers must create a system that compensates for this by automatically repositioning the sound based on the location of the soldiers.
Have a look at Wired's interview of Grant who explains how his innovative system works and what its effects are.