A method and apparatus (10) for objectively assessing acoustical performance of an in-ear device (12) having a passageway (20) extending there through use a dual microphone probe (26) that removably engages the passageway (20). The acoustical performance of the in-ear device (12) is performed with the in-ear device (12) inserted into the ear canal (14) of the user and a reference sound source (24). A clip (36) holding the probe (26) in an acoustic near field of the sound source (24) permits real time calibration thereof. The method and apparatus (10) allow on-site and in-situ measurement of a predicted personal attenuation rating (P-PAR) of the device, a subject-fit re-insertion test, an acoustic seal test, a rating test, a stability and reliability test, as well as a protection test of the device (12) with an assessment of a filtered predicted exposure level (F-PEL) at the ear for a specific noise exposure level. The apparatus (10) may be simply housed along with the sound source (24) for the in-field evaluation tests.
