Occlusion effect of earmolds with different venting systems

Area of Science:

• Audiology
• Acoustics
• Hearing Instrument Technology

Background:

• The occlusion effect (OE) is a common concern for hearing aid users, impacting sound quality and comfort.
• Traditional earmold venting strategies aim to mitigate OE but can be suboptimal.
• Quantifying OE objectively and subjectively is crucial for optimizing hearing aid fitting.

Purpose of the Study:

• To quantify and compare the occlusion effect of novel earmold vent designs against conventional methods.
• To evaluate the subjective perception of occlusion in relation to objective acoustic measurements.
• To determine the test-retest reliability of subjective and objective OE measures.

Main Methods:

• Investigated five earmold types, including conventional (1.6 & 2.4 mm circular vents), novel shell-type vents, and soft silicone eartips.
• Measured OE using a probe microphone system in nine normal-hearing listeners and ten hearing aid users.
• Assessed subjective occlusion ratings during test-retest sessions.

Main Results:

• Novel earmold vents demonstrated significantly lower OE compared to traditional vents for both participant groups.
• Soft silicone eartips yielded OE comparable to a non-occluded ear.
• Subjective occlusion ratings showed higher test-retest reproducibility than objective measurements.
• Perceived occlusion correlated more strongly with measured OE in high OE ears.

Conclusions:

• Novel earmold vent designs effectively reduce the occlusion effect.
• Subjective occlusion perception is linked to the acoustic mass within the vent.
• Vent dimensions can potentially predict perceived occlusion, aiding in hearing aid fitting.