Abstract: An evaluation apparatus comprises a brain wave acquiring unit that acquires a brain wave signal from each of a plurality of subjects; an intensity data generating unit that generates intensity data that represents an intensity of a signal component in a predetermined frequency band or a relation between intensities of signal components in a plurality of frequency bands; a correlation data generating unit that acquires pairs of two subjects for all combinations, calculates a cross-correlation coefficient for the intensity data at each point in time for the respective pairs, and generates, correlation data in the time-series form; and an output unit that generates evaluation data that numerically represents a degree of synchronization of brain wave fluctuation based on the correlation data.

Abstract: A sound pressure assessment system determines sounds to be presented by referring to a database retaining data of sounds, each of which is a pure tone. The system presents the determined sound as a first sound, and in a predetermined time after presenting the first sound, presents as a second sound a sound at least having the same frequency and the same sound pressure level as those of the first sound to the user. The system extracts an amount of change from an N1 component in response to the first sound to that in response to the second sound. The N1 components are negative components of an user's event-related potential based on points of presenting the first and second sounds as respective starting points. The system determines whether the sound pressure level of the presented sound is excessive to the user, based on the amount of change.