The Occlusion Effect
The Occlusion Effect is a sensation of increased loudness, especially in the low frequencies, of self-generated sounds, a person experiences when the ears are covered.
As defined by Gelfand, the occlusion effect is thought to be the increased perception of loudness due to the enhanced effect of the outer ear bone-conduction mechanism as low frequency sounds cannot escape the ear canal.
The occlusion effect only occurs in a normal outer/middle ear system
The occlusion effect will result in a lower threshold than when previously tested unoccluded.
Therefore, when you set up for masking, only occlude the ear in which you must route the air conduction signal, aka, the non-test, or contralateral ear.
Because the occlusion effect only occurs in normally functioning middle ears, you do not have to account for it in conductive losses/losses where there are middle ear pathologies.
As defined by Gelfand, the occlusion effect is thought to be the increased perception of loudness due to the enhanced effect of the outer ear bone-conduction mechanism as low frequency sounds cannot escape the ear canal.
The occlusion effect only occurs in a normal outer/middle ear system
The occlusion effect will result in a lower threshold than when previously tested unoccluded.
Therefore, when you set up for masking, only occlude the ear in which you must route the air conduction signal, aka, the non-test, or contralateral ear.
Because the occlusion effect only occurs in normally functioning middle ears, you do not have to account for it in conductive losses/losses where there are middle ear pathologies.