The U.S. Army has instituted mandatory hearing tests for soldiers returning from a combat zone. This is to measure the effects, on hearing, of service in a combat area, and to determine if any soldiers have suffered sufficient hearing loss to prevent them from doing their jobs. More obvious injuries have always played a role in this. For a combat soldier, you had the option of training for another job where the new disability would not interfere with performance.
This is all part of a U.S. Department of Defense effort to find better ways to detect and treat PTSD (post-traumatic stress disorder), TBI (traumatic brain injury) and any other combat related injuries that are not so obvious (to the troops in question, as well as the military). It appears that at least six percent of American Iraq and Afghanistan combat veterans have suffered TBI (traumatic brain injury), to the extent that they may have long term problems. As many as a third may suffer from the, even more difficult to detect, PTSD.
While about 60 percent of troops wounded in Iraq had undiagnosed brain injuries, a large number have ear damage as well. About ten percent of troops who have served there, whether wounded or not, are collecting disability payments for ear damage or hearing loss. This is not new. For nearly a century (since World War I, and the first large scale use of artillery, mortars and grenades), combat veterans have complained of long term hearing problems. This has led to more effort to develop electronic ear protection, that can allow troops to hear normally, when sound levels are normal, but block out very loud noises. Equipment like this is already available for those who maintain jet engines, and other loud equipment (like tanks). But making this gear rugged enough, and cheap enough, for everyone, will take a few more years. Meanwhile, there are earplugs available that will lessen the damage of very loud noises, and are rugged enough to survive battlefield use. The problem is getting the troops to wear them. Like loud music, many "ordinary" sounds of combat are ignored, but they gradually harm your hearing.