In testing, what is the required difference for two ears to necessitate speech masking?

The requirement of a 20 dB difference between the hearing thresholds of the two ears is grounded in the principles of auditory masking, particularly in the context of hearing assessments. When there is a significant difference in sensitivity between the two ears, sound presented to the ear with better hearing can be heard without interference from the poorer ear.

If the difference in thresholds exceeds this 20 dB mark, it becomes important to utilize speech masking techniques to ensure that the test results accurately reflect the hearing capability in each ear. This is because, at this level of difference, sounds that could otherwise be heard clearly by the ear with better hearing may not be heard by the poorer ear, leading to an incomplete or inaccurate assessment of hearing ability.

Utilizing speech masking helps isolate the ear being tested and accounts for any cross-hearing that may occur, thus providing a clearer picture of each ear's hearing capabilities and leading to more appropriate aid fitting and recommendations. This concept is an essential part of audiology and is implemented to ensure precise diagnosis and treatment of hearing loss.