What is the most common cause of a false air-bone gap?

A false air-bone gap occurs when there is a discrepancy between air conduction and bone conduction thresholds that does not reflect true conductive hearing loss. The most common cause of this phenomenon is a collapsed ear canal, which affects the measurement of air conduction thresholds. When the canal collapses, it can create a conductive component that skews the results, making it appear as if there is a gap between air and bone conduction thresholds when, in fact, there may be no true air-bone gap present.

In the case of a middle ear infection and outer ear blockage, while they can both lead to actual conductive hearing loss, they do not typically result in a false air-bone gap. Noise exposure can lead to sensorineural hearing loss which also does not create a false gap as it affects the pathways differently. Therefore, understanding that a collapsed ear canal can artificially raise the air conduction thresholds and produce the appearance of a false air-bone gap is crucial in audiological assessments.