Authors: Naser Salas-Husain¹; Namitha Jain²; Fatima Husain²
¹Washington University in St. Louis; ²University of Illinois Urbana-Champaign
Background: Misophonia and hyperacusis are sound tolerance disorders characterized by disproportionate reactions to everyday sounds. While misophonia involves intense emotional responses to specific triggers and hyperacusis involves heightened loudness sensitivity, their autonomic correlates remain poorly understood. This study examined heart rate (HR) and respiration (RSP) during fMRI to directly compare the physiological profiles of these conditions.
Method: Eighty-seven participants were categorized into four groups: Misophonia (M), Misophonia & Hyperacusis (MH), Hyperacusis (H), and Controls (C). Physiological data were recorded across two paradigms: a trigger task (misophonic, unpleasant, neutral sounds) and an International Affective Digitized Sounds (IADS) task (pleasant, unpleasant, neutral). Data were preprocessed using NeuroKit2 to analyze respiratory rates and time-series heart rate changes post-stimulus.
Results: Mixed ANOVAs revealed a significant group effect for respiration (p = .039), with the Misophonia group showing decreased respiratory rates and the Hyperacusis group showing increased rates compared to controls. In time-series analyses, the Hyperacusis group exhibited the largest HR decreases during misophonic sounds (~4s post-stimulus). For the IADS task, only the Hyperacusis group showed a significant condition effect (p = .029), specifically demonstrating a pronounced HR decrease during pleasant sounds.
Conclusion: These findings suggest that sound sensitivity disorders possess distinct autonomic profiles. The Hyperacusis group demonstrated the strongest physiological reactivity across both trigger and affective sound paradigms. These results highlight the importance of objective physiological measures in differentiating between phenomenologically distinct but co-occurring auditory conditions.
