What it is F-MIRE (Field Microphone in Real Ear)

F-MIRE is an objective fit testing method. It uses a small probe with dual microphones that is placed in the ear canal alongside the earplug. One microphone measures the sound pressure level outside the hearing protector, and the other measures the sound pressure level inside the ear canal (under the protector). The difference between these two measurements is the attenuation, which is used to calculate the PAR.

• Quick (typically 2-5 minutes per test)

• Objective (no user response required)

• Reliable and repeatable

• Requires specialist equipment

• Some systems are manufacturer-specific and can only test certain earplugs

• Some systems require a trained operator

Why it matters: F-MIRE is one of the most widely used fit testing methods in the UK because of its speed and objectivity. It is particularly useful for testing large numbers of workers efficiently.