They are adjustable, which means they can be set for various noise areas. If hearing is over-protected, the user will struggle to hear instructions or follow a conversation. In the case of under-protection, the user could suffer from a noise-induced hearing loss over the long-term. It is therefore important that a balance be achieved between attenuation and communication.
A leak-tight test is a test of airflow. We use airflow to make sure that no air can flow past the earpiece in the ear canal. We do a leak-tight test to ensure that the earpiece fits 100% in the ear canal, so that the only sound that goes through the ear canal, does so through the filter.
Calibration only applies to electronic equipment. While our test equipment is calibrated regularly, no hearing protection device needs to be calibrated. Rather, the device is monitored for the effective functioning of the product in the user’s ear, by performing a leak-tight check. The only reason for adjusting the filter would be if the person has subsequently moved to a different noise environment.