The Occlusion Effect
The occlusion effect is a hearing condition that typically affects those who are fitted with hearing aids. The occlusion effect is when a sound or noise, usually the person’s own voice, sounds altered in some fashion to that person. It is often described as a hollow, echoing or booming sound. While not life-threatening, it can be a psychologically distressing condition when the altered sound is the person’s own voice.
The occlusion effect is caused by a complete blocking of the outer ear canal. Many hearing aids block the ear canal in this manner. A person’s voice is conducted through her own bones. When these vibrations reach the ear canal, they become stuck between the eardrum and the blockage in the ear canal. The blockage bounces these vibrations, which otherwise would exit through the ear canal, back at the eardrum. This can cause an almost 20 decibel increase in sound pressure in the ear.
The occlusion effect has several symptoms or problems associated with it. In addition to the psychological distress it can cause by altering the sound of a voice, it can also make the sound of chewing food seem loud or excessively noisy. When a hearing aid is inserted into the ear, it can create a feeling of pressure or the sensation that the ear has been blocked. The occlusion effect can be a significant enough problem that some hearing aid users will cease to use their hearing aids.
One of the means of rectifying the occlusion effect with hearing aid devices is through the use of a vent in what is called the earmold (the body of the hearing aid). Many hearing aids are made with pressure vents, which provide no relief for the occlusion effect. To reduce the occlusion effect it is necessary for a larger hole to be created. This can be a mixed blessing because while the occlusion effect is reduced, it can create feedback and allow low frequency sound to escape.
Completely in Canal
An alternative solution to a vented earmold is the use of a specific type of completely in the canal hearing aid. These are hearing aids that are specifically made to be inserted very close to the eardrum. The idea behind this is that the aid will occupy the space in the ear where the bone conducted vibrations of a person’s own voice are generated.
While the occlusion effect is a common problem among hearing aid users, there is a second, similar condition that is sometimes mistaken for occlusion. It is called ampclusion. Ampclusion is a problem with the degree of amplification that a hearing aid has in the lower frequency range. If the lower frequencies are amplified too much, it can create a similar auditory booming effect. This is not a problem with the ear canal being occluded (covered over completely).