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.