An Inconclusive Analysis of Cochlear Dead Zones
Hornsby and Dundas evaluated 59 patients (ages 49 to 88 years, mean age 71 yrs, 34 males) with a broad range of sensorineural hearing loss (SNHL) configurations using the Threshold Equalizing Noise (TEN) SPL test to examine inner hair cell cochlear dead zones (The TEN test is the only psychophysical test commercially available [in HL and SPL versions] to measure/evaluate “dead zones”).
Hornsby and Dundas measured hearing thresholds in quiet as well as TEN and categorized the responses as positive (consistent with cochlear dead regions), negative (inconsistent with a dead region), or inconclusive. As hearing loss exceeded 60 dB HL, positive TEN results were more common. Nonetheless, positive TEN results did not necessarily correlate with increased hearing loss. Indeed, there were also positive results noted when hearing was better than 60 dB HL, arguably suggesting false positives.
However, in general, positive findings were more often found with greater hearing loss and negative findings were more common with lesser degrees of hearing loss. Some people with mild hearing loss demonstrated positive results and some with severe hearing loss had negative results.
Hornsby and Dundas noted a large number of inconclusive results. Further, when they did get positive results, their results often indicated isolated rather than contiguous spectral regions. Thus, large numbers of inconclusive results as well as the potential for false positives may render interpretation of TEN test results difficult—particularly when results are positive for high frequencies (greater than 4000 Hz).
For More Information, References and Recommendations:
Hornsby BWY, Dundas JA. (2009) Factors Affecting Outcomes on the TEN (SPL) Test in Adults with Hearing Loss. Journal of the American Academy of Audiology 20: 251-263.