[Concentration-effect and underestimation of time by acoustic stimuli]

This experiment is to examine emotional effects induced by acoustic loading on time-estimation and degree of concentration on tasks. Subjects were ten college students, who were asked to produce five second periods (estimation of time), under acoustic loading for 15 minutes. Acoustic stimuli were (1) koto-music, (2) classical music, (3) sound effect, and (4) FM-noise, with different power spectra, expected to induce different emotions in the subjects. Time-estimation and EEG alpha-rhythm were used as parameters of concentration. The main results were as follows. In general, time was underestimated when the subjects' attention was concentrated on the tasks. Acoustic stimuli with 1/f-fluctuation and pleasant emotions induced underestimation of time. Gradient of fluctuation in time-estimation also showed the same effects. With increase in acoustically induced pleasant emotions, alpha-rhythm increased, in parallel with the underestimation of time. These results suggest that emotions induced by the physical characteristics of acoustic stimuli affect mental concentration and eventually affect time-estimation.