When should double hearing protection be worn?

Double hearing protection should be worn within 100 feet of an operating engine or a P-3 Auxiliary Power Unit (APU) because the noise levels generated by these types of equipment can be particularly high and potentially harmful to hearing. In environments where noise levels exceed certain thresholds, single hearing protection may not be sufficient to prevent hearing loss or damage, hence the need for double protection.

The inclusion of factors such as operational safety regulations considers that proximity directly correlates with exposure to hazardous noise levels. Wearing double hearing protection in this specified range ensures that individuals are adequately safeguarded against the increased risk of hearing impairment due to sustained exposure in high-decibel environments. This is especially critical in aviation and military settings, where there is often substantial ambient noise from various equipment, including engines and generators.