The effects of Western musical training and musical ability on the discrimination of intervallic ordering in both tonal and post-tonal chords were examined using an oddball-paradigm experiment. Participants with different levels of formal musical training (composers and theorists, other professional musicians, and non-professionals) but with high scores from a musical aptitude test (the KMT) were recruited. The results of the study revealed a main effect for the type of musical training: composers’ and theorists’ scores differed markedly from the scores of the other participant groups, whereas professionals and non-professionals had similar response profiles. The discrimination between intervallic orderings of even the most familiar tonal chords seemed to require analysis-oriented training.