Mapping Tonal Hierarchy in the Brain

Abstract

In Western tonal music, pitches are organized hierarchically based on their perceived fit in a specific tonal context. This hierarchy forms scales that are commonly used in this Western tonal music. The hierarchical nature of tonal structure is well established behaviourally; however, the neural underpinnings are largely unknown. In this study, EEG data and goodness-of-fit ratings were collected from 34 participants who listened to an arpeggio followed by a probe tone, where the probe tone could be any chromatic scale degree and the context any of the major keys. Goodness-of-fit ratings corresponded to the classic tonal hierarchy. N1, P2 and the ERAN were significantly modulated by scale degree. Furthermore, neural marker amplitudes and latencies were significantly correlated with similar magnitude to both pitch height and goodness-of-fit ratings. This is different from the clearer divide between pitch height correlating with early neural markers (100-200ms) and tonal hierarchy correlating with late neural markers (200-1000ms) reported by Sankaran et al. (2020) and Quiroga-Martinez et al. (2019). Finally, individual differences are greater than any main effects detected when pooling participants and brain-behaviour correlations vary widely (i.e. r = -.8 to .8).