Audiometric Masking is performed to provide accurate results of Pure Tone Audiometry by separating the ears acoustically; this means that the non-test ear is unable to assist the test ear.

Across the world there are different rules for masking however some general rules of masking are:

• Masking is needed where the difference between unmasked Air Conduction Thresholds is 40dB or more when using Supra Aural Headphones, or 55dB if using Insert Headphones. Reference found here.
• Masking is needed where the difference between the unmasked Bone Conduction and Air Conduction thresholds of either ear is 10dB or more.
• Masking will be needed where there is a Bone Conduction threshold of 40dB or more than that of the Air Conduction threshold, where Supra aural headphones have been used, or by 55dB where Insert Headphones have been used.