Observations on the relations among occlusion effect, compliance, and vent size.

In a clinical experiment, it was found that there is a high correlation between the compliance measured by tympanometry and the minimum size of the earmold vent, which just solves the client's occlusion problem related to his/her own voice when using a hearing aid. For ears with sensorineural hearing losses, compliance explained 59 percent of the variation in vent size, whereas the average low-frequency hearing loss explained as little as 0.3 percent. In a laboratory experiment, the objective occlusion effect measured with the participants' own voices showed a similar relationship with compliance. Whereas the former relationship between compliance and vent size may be explained by a simple model, the latter relationship turns out to be the opposite of what a first-order model predicts. Hence, compliance must be indicative of another aspect of the occlusion mechanism, which has a more profound influence on the observed occlusion effect than compliance itself.