Age-related Effects on the Threshold Equalizing Noise (TEN) Test

Abstract

Some individuals with sensorineural hearing loss have certain places along the basilar membrane where inner hair cells and/or neurons are damaged or destroyed and consequently have ceased to function. These regions have been referred to as "dead regions" in the literature. The TEN (HL) test is a relatively quick behavioral test designed to identify cochlear dead regions. The test relies on the detection of pure-tone signals in the presence of a specially designed broadband noise (threshold equalizing noise) masker. The TEN (HL) test was validated on young to middle aged adult listeners, an age group which does not represent that of all adults with hearing loss. The goal of this study was to evaluate the effects of age on the TEN (HL) test. The TEN (HL) test was administered to 18 younger and 18 older adults with normal to near-normal hearing sensitivity at seven different frequencies in three different levels of TEN noise. These measures were conducted twice to assess test re-test reliability. The older group demonstrated significantly poorer (higher) SNRs compared to the younger group at all three TEN noise levels and for all seven test frequencies. The greatest difference between groups was observed for the highest level of TEN noise. The greatest difference in SNRs was at 4000 Hz compared to other test frequencies for both groups. Both groups performed best (lowest SNRs) at 4000 Hz compared to the other test frequencies. Finally, a main effect of trial was found, revealing that both groups performed statistically better (lower SNRs) on the second trial; however the small magnitude of this improvement (0.37 dB), suggests that the TEN (HL) test has good repeatability for clinical use, at least within the time period assessed. Although there were significant differences between the two groups, overall the TEN (HL) test yielded accurate results in classifying all normal to near-normal hearing participants as not having a dead region. The significantly higher (poorer) SNRs associated with age, combined with the expected difference in SNRs associated with hearing loss, may allow for older hearing-impaired individuals to demonstrate abnormally high SNRs on the TEN (HL) test in the absence of a cochlear dead region. Future studies that include younger and older participants with normal hearing and hearing loss are needed to assess these differences and examine whether different norms are needed for this older population.