The responses of electroencephalogram (EEG) to different odors and their densities were studied on four men and two women at rest while sitting. The odors examined were citrus, floral and lavender, and their densities were 100 ppb and 200 ppb. The odors were released for ten minutes from a duct to fill the room completely. The subjective estimation indicated that citrus had a tendency to be the most comfortable odor in this study, but it was not significant. To evaluate changes of EEG, the power spectra of frequency-fluctuation of awave (Fz) and the rate of α, β and β/αwave (Oz, Fz) were calculated. The rate of awave (Oz) in the period of giving out the citrus at 100 ppb was significantly (p0.05) higher than that of the lavender. The rate of β wave (Oz) in the period of giving out the floral at 200 ppb was significantly (p 0.05) higher than that of the lavender. The regression coefficient of the power spectra of frequency-fluctuation of α wave in the period of giving out the lavender at 100 ppb was significantly higher than those in the other periods of the experiment. The regression coefficient of the power spectra of frequency-fluctuation of α wave for lavender given out at 200 ppb was significantly (p0.01) higher than those for the other odors given out. It seems that the regression coefficient of the power spectra of frequency-fluctuation of α wave can be used for the evaluation of psychophysiological responses.
