Accounting for the Occlusion Effect with Insert Earphones.

Area of Science:

• Audiology
• Hearing Science
• Biomedical Engineering

Background:

• The occlusion effect (OE) can lead to spurious results in bone conduction (BC) testing.
• Understanding when to account for OE is crucial for accurate audiological assessments.
• Variability in OE with insert earphones (IEs) necessitates further investigation.

Purpose of the Study:

• To quantify the occlusion effect (OE) during BC threshold measurements.
• To compare OE under conditions of partial insertion (PI) versus full insertion (FI) of IEs.
• To evaluate OE when one or both ears are occluded during BC testing.

Main Methods:

• A within-subjects design was employed with 22 adult participants.
• BC thresholds were measured at 250, 500, and 1000 Hz under seven occlusion conditions.
• Conditions included unoccluded, PI, and FI of IEs in one or both ears.

Main Results:

• Mean OEs ranged from 5-13 dB, except in the FI condition at 1000 Hz (<3 dB).
• Differences between PI and FI conditions were observed across frequencies and occlusion states.
• Threshold shifts were consistently greater for PI compared to FI; one-ear vs. both-ears differences were not significant.

Conclusions:

• Occluding the ear during initial BC measurements can artificially elevate thresholds and create air-bone gaps.
• Initial BC testing at 250, 500, and 1000 Hz should be performed without occlusion.
• OE must be considered even with IEs fully inserted (flush with the ear canal) to prevent insufficient masking.