Raul Sanchez-Lopez1,2, Gerard Encina-Llamas1
1Hearing Systems Section, Department of Health Technology, Technical University of Denmark, Kgs. Lyngby, Denmark
2Interacoustics Research Unit, Kgs. Lyngby, Denmark
A data-driven auditory profiling approach has been recently proposed to provide a more accurate and sensitive clinical evaluation of hearing. Such approach identified four different groups of hearing-impaired listeners that reflected different degrees of two independent types of auditory deficits: speech-intelligibility deficits and loudness perception deficits. Despite the four groups showing differences in several supra-threshold tasks, audiometric thresholds were also significantly different across the four auditory profiles. In the present study, loudness-growth functions obtained in 75 listeners with different hearing abilities and classified as belonging to one of the four auditory profiles (A-D) are presented and discussed. Furthermore, a state-of-the-art computational model of the auditory nerve was used to explore the potential peripheral pathologies that could lead to the loudness-growth functions observed in each of the four profiles. The aims of the study were 1) to evaluate the association between neuronal rate and loudness perception in the four groups of hearing-impaired listeners, and 2) to investigate the role of outer-hair-cell loss and inner-hair-cell loss on the shape of the loudness-growth functions. The experimental results showed that loudness-related deficits were associated with steeper loudness functions and increased hearing thresholds. In contrast, the loudness functions of listeners belonging to profiles with speech-related deficits were shifted towards higher levels. The model simulations were qualitatively similar to the loudness-growth functions obtained in each of the profiles, although the model was only fitted to the audiometric threshold of each profile without any auditory nerve dysfunction. This suggests that abnormal loudness-growth functions can be mainly explained by peripheral processes and that the role of high-frequency inner-hair-cell loss on the excitation patterns may dominate the abnormal loudness perception, especially at high presentation levels.
Acknowledgements: This work was partially supported by the Better hEAring Rehabilitation project (BEAR) Innovation Fund Denmark Grand Solutions 5164-00011B, and UHEAL: Uncovering Hidden Hearing Loss funded by the Novo Nordisk foundation.