At what time-weighted average (TWA) noise level should single hearing protection devices (HPDs) be used?

The appropriate time-weighted average (TWA) noise level for using single hearing protection devices is established based on guidance and regulations concerning occupational noise exposure. In most safety guidelines, it is recommended that when noise levels exceed 85 dB(A) TWA, single hearing protection devices should be utilized to help prevent hearing loss.

Using hearing protection below this threshold may not be necessary given that the risk for hearing damage is significantly reduced in quieter environments. The guidelines consider both the efficacy of protection devices and the feasibility of using them. Thus, while options discussing higher decibel levels suggest that hearing protection is needed at elevated exposures, the threshold for mandatory use of single HPDs is clearly placed at 85 dB(A) TWA or higher.

Therefore, the recommendation is to use single hearing protection devices when noise levels are at 85 dB(A) TWA or above, not below it, as lower levels do not generally pose a significant risk of hearing damage that would necessitate the use of such devices.