Assessing brain wave functions that are evoked by auditory stimuli is an important area of study that may lead to the development of brain computer interface (BCI) systems that incorporate natural features of auditory perception such as tone, pitch, and sound-source locations (e.g. direction). We analyzed event-related potentials (ERPs) evoked by auditory stimuli that are applicable to BCI systems. In recent studies, sound localization systems have been intensively studied in order to enhance BCI system development in a way that reproduces a virtual 3D auditory environment, applicable to human-machine communications. We conducted experiment using a sound localization system in which subjects were instructed to listen to a sound cue and answering the relative direction (i.e. the direction to which the sound cue is emitted from an observer) of the sound source. For each trial, a target direction was indicated by the experimenter, although the direction of the sound cue emitted during the trials was not necessarily the target direction. Changes in brain activity were measured using an electroencephalogram (EEG) . Experimental results showed that prominent excitations in EEG signals were observed during a trial where the target direction corresponded to the sound source direction, by subtracting the mean EEG signal of the non-target trials from that of the target trials.
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