Okluusioefektin

Okluusioefektin, known in English as the occlusion effect, is a psychoacoustic phenomenon observed when the ear canal is occluded by an object such as an earplug, a canal-type hearing aid, or an earmold. The effect is characterized by an increased perception of low-frequency sounds transmitted through bone conduction when the ear canal is blocked.

The mechanism involves the way sound energy from skull vibrations interacts with the air-filled ear canal. When the canal is occluded, part of the energy that would normally escape through the canal is redirected, increasing the pressure at the eardrum and creating a resonance in the trapped air. This leads to an amplification of low-frequency components, typically most noticeable below about 1 kHz. The magnitude of the occlusion effect depends on the degree of occlusion, canal geometry, venting, and the presence of any conductive hearing loss.

Clinical relevance is significant in the fitting and design of hearing devices. The occlusion effect can cause a perceived “plugged” or muffled sensation and an unwanted bass boost, particularly with bone-conduction or canal-type devices. To mitigate it, audiologists may use vented earmolds, open-fit designs, or devices with occlusion-reducing features and signal processing aimed at reducing low-frequency amplification.

Measurement and management strategies focus on assessing the perceptual impact of occlusion during fitting and choosing configurations that balance clarity, comfort, and naturalness of sound. In some cases, listeners adapt over time, and the occlusion effect becomes less bothersome with gradual acclimatization.