Yes, routers can be extremely noisy, over 100dBA in the worst cases. As a general rule, 70dBA is considered acceptable, and 85dBA is the trigger level where precautions must be taken to prevent hearing damage. Although often referred to as earplugs or ear defenders, hearing protection is more appropriate as a generic term. Different types of hearing protection fall into two categories — those inserted within the ear and those covering the ears (earmuffs). The choice of hearing protection is personal, but for maximum safety and convenience, earmuffs are the best.