In the early stages of presbycusis, patients complain of reduced speech perception
in noisy environments, even if there is no increase in hearing thresholds. This condition
is often referred to as "hidden hearing loss". Current diagnostic metrics,
such as a reduced amplitude of the ABR Wave I, elevated hearing threshold in the extended
high-frequency range (EHT), a decreased amplitude of middle ear muscle reflex etc.,
mainly focus on finding the suitable biomarkers for pathological changes in the peripheral
auditory system. However, the results are inconsistent. Mismatch negativity (MMN)
is a long-latency cortical auditory evoked potential and is generated when an individual
automatically detects a change in sound. This change detection relies on the brain's
memory traces of the regularity of sound stimuli. The aim of this study was to prove
if MMN could also be used as a diagnostic metric for hidden hearing loss in human
adults. 73 subjects with normal hearing were included in this study. All participants
underwent an extended pure-tone audiogram examination, a middle ear muscle reflex
assessment and a subsequent MMN assessment with 2 different stimuli. Pearson correlation
analyses revealed a statistically significant negative correlation between age and
the amplitude of MMN elicited by verbal stimuli (R=-0.18, p=0.029). Regarding the
correlation between the amplitude of MMN induced by verbal stimuli and the EHT, no
statistically significant correlation was found. However, when we divided all participants
into two group based on their EHT, the MMN amplitude in the group with EHT<0 dB was
significantly higher than that in the group with EHT>0 dB (p=0.05). Thus, speech-induced
MMN may serve as a potential biomarker for hidden hearing loss in human adults.
