Pauline Devolder^1,2, Hannah Keppler^2,3, Sarineh Keshishzadeh, Baziel Taghon, Ingeborg Dhooge^3,4, Sarah Verhulst¹

1 Hearing Technology @ WAVES, Department of Information Technology, Ghent University, Zwijnaarde, Belgium

2 Department of Rehabilitation Sciences, Ghent University, Ghent, Belgium

3 Department of Ear, Nose and Throat, Ghent University Hospital, Ghent, Belgium

4 Department of Head and Skin, Ghent University, Ghent, Belgium

In our study “The role of hidden hearing loss in tinnitus: Insights from early markers of peripheral hearing damage,” we aimed to determine whether “hidden hearing loss” could play a role in the development of tinnitus. Hidden hearing loss refers to damage to the auditory nerve pathways (see Figure) that doesn’t show up in regular hearing tests, but can make it challenging to understand speech in noisy environments. Hidden hearing loss often develops in people in their 40s or 50s, but could it also be a cause of tinnitus?

To explore this, 54 participants underwent an EEG test to measure the neural response to different sounds. We tested four groups of subjects: a younger group without tinnitus, a younger group with tinnitus, an older group without tinnitus, and an older group with tinnitus. We found differences between younger and older people, but not between those with and without tinnitus. This suggests that age plays a significant role in hidden hearing loss, highlighting the importance of considering participant age in both current and future tinnitus studies. Age-related hearing changes may affect the results and are not always linked to tinnitus.

We also assessed how well each group understood speech in quiet and noisy conditions. An interesting finding emerged: when testing speech that was filtered to include only low-frequency sounds in a noisy background, the older group with tinnitus actually performed better than the older group without tinnitus. This could indicate that people with tinnitus may have increased sensitivity to certain low-frequency sounds. Further analysis, including questionnaire responses, showed that those with more severe tinnitus (based on the Tinnitus Handicap Inventory and the Tinnitus Functional Index) or hyperacusis (based on the Hyperacusis Questionnaire) performed better on the low-frequency speech tests in noise.

Based on these findings, we recommend that future research focuses more on the processing of low-frequency sounds and clearly distinguishes between participants with tinnitus and hyperacusis. In upcoming studies, we plan to include subject groups with only tinnitus, only hyperacusis, and those with both conditions. This will provide new insights into the distinct mechanisms underlying tinnitus and hyperacusis. By gaining a better understanding of how different sounds are processed in the auditory pathway, we aim to discover new ways to help people with hyperacusis and/or tinnitus.

Since we found no differences between the groups with and without tinnitus, our EEG measurements show no evidence of additional hidden hearing loss in people with tinnitus.