Distinct pre-attentive responses to non-scale notes: An auditory mismatch negativity (MMN) study

Objective: The aim of the present study was to examine patterns of neural activity in response to variations in scale notes and alterations from a scale note to a non-scale note.Methods: Event-related potentials (ERPs) were recorded in response to scale and non-scale violin notes using an odd-ball mismatch negativity (MMN) paradigm. Standard stimuli were set to the scale note A4 (440 Hz). Deviant stimuli included two scale notes (scale-B, B4 = 494 Hz; scale-C, C5 = 523 Hz) and a non-scale note halfway between them (non-scale, B4 + 42¢ = 506 Hz).Results: MMN amplitude elicited by the non-scale was significantly larger than that elicited by the scale-B and scale-C, which did not differ significantly from one another.Conclusion: The current results suggest that the human brain may possess pre-attentive mechanisms for extracting relational aspects among sounds of the musical scale.Significance: The results indicate that non-scale notes may be processed in a different way even in the pre-attentive stage than scale notes.

► We compared pre-attentive processing of scale notes defined by an equal tuning system for Western music and non-scale notes (a semitone + a quartertone) using MMN, the amplitude of which is considered to reflect discriminability of the deviance.
► MMN elicited by changes from a scale note (A4 = 440 Hz) to a non-scale note deviant (B4 + 42¢ = 506 Hz) was larger than MMNs by alteration from the same scale note (A4) to scale note deviants (B4 = 494 Hz and C5 = 523 Hz) while MMNs for the two scale note deviants that sandwiched the non-scale note deviant did not differ.
► The present findings may demonstrate that the human brain possesses pre-attentive mechanisms for extracting relational aspects among sounds of the musical scale.