At what noise level is double hearing protection required?

• A. 85 dB
• B. 120 dB
• C. 105 dB
• D. 95 dB

Answer: (C)

The main idea here is how much protection is needed for very loud noise. When noise hits 105 dB, you must use double hearing protection. That means wearing two devices at once—typically earplugs plus earmuffs—to boost the total attenuation beyond what a single device can provide. This extra protection helps account for factors like imperfect fit and movement, and it keeps your actual exposure within safe limits even if there are brief spikes in sound or slight gaps in the seal.

Single protection is usually enough at lower levels because a single device already reduces most of the noise you’re exposed to, and typical work durations are accounted for in permissible exposure limits. Extremely loud levels, like around 120 dB, are dangerous enough that protection is essential, but the defined threshold at which double protection becomes mandatory is 105 dB.