Authors: Laura Hansen¹, Julie Jacobsen¹, Jaime Undurraga², Jesper Hvass Schmidt³, David McAlpine⁴, Tobias Neher¹, Lindsey Van Yper¹
¹Technical Audiology Section, Research Unit for ORL – Head & Neck Surgery and Audiology, Odense University Hospital & University of Southern Denmark; ²Interacoustics Research Unit, Technical University of Denmark; ³Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark; ⁴Department of Linguistics, The Australian Hearing Hub, Macquarie University
Background: Differences in the arrival time of sounds at the two ears—interaural time differences (ITDs)—enable sound localization and speech perception in complex listening environments, such as noisy classrooms. The brain’s ability to process ITD can be disrupted by recurrent episodes of otitis media (OM) during early childhood—a critical period for auditory development. Current assessments of ITD sensitivity in children primarily rely on psychoacoustic measures that are influenced by attention, motivation, and cognition. An objective neural measure of ITD could provide an alternative. Here, we employ the interaural time modulation following response (ITM-FR) to objectively evaluate binaural unmasking in children with or without a history of OM.
Methods: A total of 82 normal-hearing children aged 6–12 years were included: 39 with a medically documented history of OM and 43 controls with no parent-reported history of OM. Neural sensitivity to ITDs was assessed using the ITM-FR, elicited by periodic ITD transitions changing between diotic and dichotic (ITD of 200, 400, or 800 μs) presentation. Using the same ITDs, binaural unmasking was assessed behaviourally with speech reception thresholds (SRTs) measured with a paediatric speech-in-noise test.
Results: Preliminary analyses show consistent effects for both neural and behavioural measures, with larger neural responses and improved SRTs for larger ITDs. For the behavioural measure, a significant ITD-by-group interaction is observable, with no significant post hoc group differences after correction for multiple comparisons.
Conclusion: Larger ITDs are associated with larger neural responses and lower (better) SRTs. No clear group differences are observable using binary OM classification of the participants. Future analyses will examine the effects of the individual OM history (e.g., type, age of onset and offset, number of episodes, and grommet history) on neural and behavioural outcomes.
