Can hearing protection and glasses be worn at the same time?
The attenuation of an earmuff obviously depends on the seal between the ear cushion and the head.
Gaps provide an easy path for noise to enter the ear canal, negatively affecting the amount of attenuation. Several factors influence the size of "gaps":
- Contact pressure of the earmuffs
- Head shape and size
- The nature of the ear pad material (stiffer material creates more gaps)
- Thickness of the glasses frame
- Shape of the glasses frame
In a study conducted at the Howard Leight Acoustical Laboratories, 5 models of protective eyewear were tested in combination with two popular earmuffs, (Howard Leight Thunder T3 and Howard Leight Leightning L3). Hearing tests were conducted on the subjects (in the open field) when they wore the earmuffs alone, and then in combination with the goggles to determine if there was a change with the combination.
The results show that for goggles with a thin frame (a width of 2mm or less at the temples where the hearing protector pads come into contact with the frame), the goggles do not cause a significant decrease in attenuation - the mean attenuation (SNR) was almost the same as the hearing protector without goggles. However, safety glasses with wider frames cause critical gaps, resulting in a weaker attenuation, especially in the low frequencies. Goggles with an unusually wide frame of 6mm at the temples cause a drop of 9 to 12 dB in the low and high frequencies.