Authors: Santhosh Periyasamy¹; Prashanth Prabhu¹
¹All India Institute of Speech and Hearing (AIISH)
Background: Misophonia is a sound tolerance disorder characterised by intense emotional and autonomic responses to specific pattern sounds. Despite growing interest in its neurophysiological underpinnings, objective evidence from the middle latency response (MLR), a marker of thalamocortical auditory transmission, remains unexplored. This study investigated MLR latency and amplitude characteristics in individuals with misophonia across multiple stimulus conditions.
Method: Twenty adults participated: 10 with clinically identified misophonia and 10 age- and gender-matched controls. MLR was recorded using click, 500 Hz tone burst, and 4 kHz tone burst stimuli. Latencies and amplitudes of Na, Pa, Nb, and Pb components were compared using independent samples t-tests with Cohen’s d effect sizes.
Results: MLR latency components were significantly shorter in the misophonia group across all stimulus conditions (p < 0.001). Effect sizes were uniformly large for click (Na: d=1.87; Pa: d=3.36; Nb: d=4.30; Pb: d=4.55), 500 Hz (Na: d=2.14; Pa: d=3.13; Nb: d=3.68; Pb: d=3.69), and 4 kHz tone bursts (Na: d=2.23; Pa: d=3.11; Nb: d=2.55; Pb: d=3.11). Amplitudes showed no significant between-group differences under any condition, indicating that neural timing rather than neural magnitude is the primary neurophysiological distinguishing feature in misophonia.
Conclusion: Misophonia is characterised by significantly shorter MLR latencies with preserved amplitudes, indicative of accelerated but not augmented thalamocortical transmission. This dissociation between latency and amplitude points to a timing-based neural hyperexcitability and supports MLR as a promising objective tool in misophonia assessment.
