The Effect of Different Adaptation Formulas on Mid-Latency Auditory Evoked Potentials in Adults with Hearing Aids

We were conducting this study to evaluate the effects of different hearing aid adaptation formulas on middle latency responses (MLR) in adult hearing aid users.

The study included 72 participants: those with moderate hearing loss using hearing aids with two different formulas for the last year, those with moderate hearing loss not using hearing aids, and those without hearing loss. Sixteen participants using NAL-NL1 and NAL-RP formulas were group 1; twenty using NAL-NL2 and DSL formulas were group 2; fifteen with hearing loss not using devices were group 3; and twenty-one without hearing loss were group 4. We obtained and compared MLR responses, including Na latency, Pa latency, and Na-Pa amplitude.

Group 1 mean Na-Pa amplitude value was found to be higher than group 2 (p = 0.001). No significant difference was observed between group 1 and group 2 in terms of Na latency and Pa latency values (p = 0.001; p = 0.035). It was observed that the mean Na-Pa amplitude values in group 1 and group 2 were higher than group 3 (p = 0.001), but this elevation reached the level of statistical significance only in group 1. No difference was observed between group 1, group 2, and group 3 in terms of Na latency and Pa latency values (p = 0.001; p = 0.035). Compared with those without hearing loss (group 4), participants with hearing loss (group 1, group 2, and group 3) had longer Na latency and Pa latency values (p = 0.001; p = 0.035), and Na-Pa amplitudes were lower (p = 0.001). The effect of current (tested) hearing aid usage time on Na latency, Pa latency, and Na-Pa amplitude values of group 1 and group 2 was not observed. In all groups, there was a positive correlation between audiometric airway/bone conduction pure tone averages and speech acquisition threshold values, Na latency and Pa latency values, and a negative correlation between Na-Pa amplitude values. In all groups, there was a negative correlation between speech discrimination scores and Na and Pa latency values, as well as a positive correlation between Na and Pa amplitude values. There was a positive correlation between age and Pa latency values in all groups, as well as a negative correlation between Na and Pa amplitude values.

MLRs are affected by the presence of hearing loss, the use of hearing aids, and different hearing aid adaptation formulas. MLR measurements with a hearing aid can be used as an objective test to evaluate the benefit of hearing aid use.