Music can be experienced in various acoustic qualities. In this study, we investigated how the acoustic quality of the music can influence strong emotional experiences, such as musical chills, and the neural activity. The music’s acoustic quality was controlled by adding noise to musical pieces. Participants listened to clear and noisy musical pieces and pressed a button when they experienced chills. We estimated neural activity in response to chills under both clear and noisy conditions using functional magnetic resonance imaging (fMRI). The behavioral data revealed that compared with the clear condition, the noisy condition dramatically decreased the number of chills and duration of chills. The fMRI results showed that under both noisy and clear conditions the supplementary motor area, insula, and superior temporal gyrus were similarly activated when participants experienced chills. The involvement of these brain regions may be crucial for music-induced emotional processes under the noisy as well as the clear condition. In addition, we found a decrease in the activation of the right superior temporal sulcus when experiencing chills under the noisy condition, which suggests that music-induced emotional processing is sensitive to acoustic quality.

During singing practice, people are often told to sing in bright voice to improve singing performance. The purpose of this study is to determine how singing practice affects the acoustical characteristics and expressiveness of “brightness.” In this study, eight singers (having experience in chorus for 0 to 13 years) sang three types of humming with G4 (392 Hz). Singers were told to sing either “bright,” “dark,” or “normal” humming. Subjects (n = 16) listened to different types of humming in pairs, and judged which was brighter. The results showed that the subjects perceived “bright” humming as bright. As singers practiced longer, their “brightness” was more expressive. Acoustical analysis revealed that fundamental frequencies of “bright” humming were higher than dark humming by 3 Hz, and that bright humming had higher amplitude in spectrum from 4900 to 6400 Hz by 4.5 to 6.5 dB. In the following experiment, subjects listened to and judged the brightness of humming, whose amplitude in the range was systematically amplified. As a result, the more amplified the humming had in the range, the more likely subjects evaluated it as bright. Our results suggest that singers can obtain the ability to express “brightness” by producing these acoustical characteristics through practicing singing.

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