Objective: The aim of the present study was to identify the variation of cerebral hemodynamics in relation to listening to chord progressions involving consonant or dissonant chords based on western music theory by near-infrared spectroscopy. We also tried to find out the influence of musical education on the cortical hemodynamics.
Methods: Twenty subjects participated in this study. They were classified into two groups, namely persons with and without special musical training histories. We used two types of chord progressions involving consonant and dissonant chords as stimuli. Then, the hemodynamics of each group was analyzed by optical topography to investigate the effects of each type of chord in the areas of left and right auditory cortices.
Results: In the left auditory cortex (superior temporal cortex), the group with higher musical training showed a significant increase in oxyhemoglobin (oxy-Hb) when listening to dissonant chords as compared with consonant chords, while the group without higher education for music did not show significant changes in oxy-Hb between consonant chords and dissonant chords. No significant changes in oxy-Hb in the right auditory cortex were observed in response to either chord, neither in the group with higher education for music, nor in the group without it.
Discussion: Our results suggest that special musical training could enhance music-syntactic processing in the left auditory area and react more sensitively to the dissonant chords.