The presence of noise during the performance of cognitive tasks involving such as memory, commonly causes a subjective experience of annoyance, which can lead to a decline in performance. This tendency is stronger in response to meaningful noise, such as music and conversation, than for meaningless noise, such as the sound of traffic, and heating ventilating and air-conditioning noise. In designing a comfortable sound environment, it is important to understand the relationship between not only the measurable aspects of noise, such as the sound pressure level, but also the qualitative aspects, such as the degree of meaningfulness of the noise, and the subjective experience of annoyance. On the other hand, it is well known that the transient event-related potentials (ERPs) in the brain wave elicited by internal or external stimuli are related to the operation of selective attention. In this study, the effects of meaningfulness of the external noise on selective attention during mental task were considered by psychophysiological experiment. First, we examined differences in the Global Field Power (GFP) for ERPs during the auditory odd-ball paradigms under the meaningful noise or meaningless noise. In addition, the principal component analysis (PCA) was adopted to define a set of components on P300 GFP.
