Have you considered Surefire's EarPro Sonic Defenders? They accomplish the task of allowing normal sounds to pass, but protecting you from louder sounds, like gunfire. They use a simple mechanical sound filter...nothing electronic. I was in the market for electronic ears for the same reason, but the price held me back. Sonic Defender's are $10 a pair, so if you don't like them it's not the end of the world. I chose them over electronic ears because of price, weight, and the fact that my sunglasses got in the way of the ear muffs.