Investigating Neural Responses to Chord Changes: Event-related Potentials in a Musical Oddball Task

Abstract

We investigated event-related potentials (ERPs) elicited by chord changes using a custom-built electroencephalography-based decoding system. An oddball paradigm was employed to examine how harmonic structures influence auditory deviance detection, extending the previous work on pure tones. To quantify the neural responses, we used a discriminant score based on linear discriminant analysis, offering an objective measure of response strength. Experiments with healthy adults revealed that pitch changes in minor chords, particularly from lower to higher ranges, elicit the strongest ERP responses, suggesting a saliency effect of pitch height. Mode changes (e.g., major to minor) showed greater variability, possibly because of individual differences in perception and musical background. Importantly, compared to single tones, chords engage higher-level auditory processing, owing to their harmonic complexity. This study demonstrates the utility of ERP-based measures for investigating neural responses to structured auditory stimuli and highlights how harmonic features contribute to attentional modulation in music perception.