TEN stands for Threshold Equalising Noise. This is a type of masking noise that is presented to the ear being tested (as opposed to the non-test ear during masking in conventional pure tone audiometry, to prevent cross hearing of sound).
TEN testing is performed when one suspects a dead region i.e. a region of the cochlea where inner hair cell damage leads to a non-functioning region of the cochlea. Such a scenario would cause the audiologist to increase the sound level during pure-tone audiometry. At some point, the pure tone that would normally be heard in the dead region might still be detected via off-frequency listening i.e. the sound vibration spreads to a functioning region of the cochlea. The action of off-frequency listening would cause an under-estimation of the true hearing loss within the dead region, and this could ultimately affect patient care. Introducing TEN prevents off-frequency listening, hence audiologist is able to accurately diagnose the presence of a dead region.
To learn more about the TEN Test please watch the following video tutorial,
References and caveats
Moore, B.C.J. (2004) Dead regions in the cochlea: Conceptual foundations, diagnosis and clinical applications. Ear and Hearing, 25, pages 98-116.