A neurophysiological study into the foundations of tonal harmony

Abstract

Our findings provide magnetoencephalographic evidence that the mismatch-negativity response to two-note chords (dyads) is modulated by a combination of abstract cognitive differences and lower-level differences in the auditory signal. Participants were presented with series of simple-ratio sinusoidal dyads (perfect fourths and perfect fifths) in which the difference between the standard and deviant dyad exhibited an interval change, a shift in pitch space, or both. In addition, the standard-deviant pair of dyads either shared one note or both notes were changed. Only the condition that featured both abstract changes (interval change and pitch-space shift) and two novel notes showed a significantly larger magnetoencephalographic mismatch-negativity response than the other conditions in the right hemisphere. Implications for music and language processing are discussed.

Fig. 1

Diagram of conditions. Each arrow connecting a pair of dyads represents one tested condition.

Fig. 2

Magnetoencephalographic analysis. (a) A representative participant’s response to a dyad as deviant (dark line) versus standard (light line); (b) scalp distribution at peak magnetic mismatch field. The contour plot shows that the underlying evoked field is likely generated over auditory cortex, as this pattern matches the pattern generated by the pretest M100 response to a single tone.

Fig. 3

(A) Mean deviant peak amplitude (fT) for (a) left hemisphere, (b) right hemisphere. (B) Mean deviant peak latency (ms) for (a) left hemisphere, (b) right hemisphere. (C) Root mean square difference amplitude (fT) between 100 and 300 ms for (a) left hemisphere, (b) right hemisphere. In all charts the error bars indicate one standard error of the mean.