The TEN(HL) test was developed to provide clinicians with a quick and easy way to identify cochlear dead regions. The test consists of measuring pure tone thresholds in a special masking noise, called the TEN (Threshold Equalizing Noise).
A dead cochlear region is defined as a region of the cochlea where there are no functioning inner hair cells and/or neurons. (Moore, 2001). When a pure-tone signal “falls” into a dead region, it can be heard by neighboring hair cells, if the intensity of the signal is loud enough. This is because the pure tone produces sufficient basilar-membrane vibrations in neighboring areas of the cochlea, where there are surviving IHCs and neurons. This phenomenon is defined as “Off Frequency Listening”. Clinically, this will present as a threshold on the traditional pure tone audiogram, but it may not be the real threshold. It is not possible to use traditional pure tone audiometry to determine if there is a dead region present; the TEN test was developed for this very purpose.
A dead region at a particular frequency is indicated when a masked threshold is at least 10 dB or more above the level of the TEN and the masked threshold is at least 10 dB above the non-masked threshold.
NOTE: the TEN test is performed ipsilaterally, meaning that the tone and the noise are presented in the same ear. It can only be conducted with TDH39, DD45 and Insert earphones headphones.
A dead region at a particular frequency is indicated when a masked threshold is at least 10 dB or more above the level of the TEN and theMasked threshold is at least 10 dB above the non-masked threshold.
If dead regions are present, this may have important implications for fitting hearing aids and for predicting the likely benefit of hearing aids. When a patient has a dead region, there may be little or no benefit from hearing aid amplification for frequencies well inside the dead region (Moore 2009).
Identifying a cochlear dead region can:
Moore, B. C. J. (2001). "Dead regions in the cochlea: Diagnosis, perceptual consequences, and implications for the fitting of hearing aids," Trends Amplif. 5, 1–34.
Moore, B. C. J. (2009). “Audiometer Implementation of the TEN (HL) Test for Diagnosing Cochlear Dead Regions”.