What is the correct first step to mask for air conduction thresholds?

The correct first step to mask for air conduction thresholds is to start the NBN (narrowband noise) masker at the non-test ear (NTE) threshold plus 10 dB. This approach ensures that the noise level is sufficient to effectively mask the non-test ear, preventing it from responding during the test of the test ear. By setting the masker level just above the NTE's threshold, it creates a situation where only the test ear's responses can be measured, allowing for accurate air conduction threshold determination.

This method is grounded in the principles of masking, which aim to eliminate cross-hearing and ensure that the thresholds measured are valid for the ear being tested. Effective masking therefore requires initial levels that are confidently above the threshold of the non-test ear, making starting at NTE threshold plus 10 dB a well-accepted practice in auditory assessments.