When should masking be employed for air conduction (AC) testing?

Masking should be employed for air conduction testing when there is a need to isolate the testing ear from the influence of the non-testing ear, especially in situations where sound presented to one ear may be heard by the other ear due to cross-hearing. This typically happens when the difference in thresholds, known as interaural attenuation, is exceeded by the intensity of the sound presented. Interaural attenuation refers to the loss of sound energy that occurs while sound travels from one ear to the other, and it varies for different transducers.

In the context of air conduction testing, if the difference in threshold levels between the two ears exceeds the interaural attenuation, it raises the possibility that the sound may be heard by the non-test ear, leading to inaccurate results. Thus, masking is crucial to ensure that the ear being tested is the one truly responding to the sound stimuli, allowing for an accurate assessment of hearing capabilities.

This rationale applies to a range of clinical situations, including when testing moderate to severe hearing loss, where the risk of crossover is significant. Proper masking strategies safeguard the integrity of the audiological assessment and guide effective treatment planning.