Ambient Noise Effects on Event-Related Potentials during Cognitive Activation

Abstract

The aim of this study was to characterize the neural activation that was associated with the performance of intellectual activities under the influence of Brownian noises that were similar to environmental noises in real spaces. An N-back task comprising 2 components, i.e., verbal and spatial tasks, was used to study working memory during 4 types of auditory stimuli. The 4 types of auditory stimuli were as follows: sounds with frequency characteristics of Brownian noise [No Modulation (NM)] and with their amplitudes modulated 0.05-1 Hz, and sounds with frequency characteristics of White (slope of power spectral density, 1/f0), Pink (1/f), and Brownian noise (1/f2). Event-related potentials (ERPs) were recorded from 60 electrodes on the scalp and analyzed. Seven healthy men who were 21-23 years old participated in the experiments. For the NM, the root mean squares (RMS) of the ERPs that were observed included a negative peak component around 150 ms in the parietooccipital area (N1) and a positive component around 330 ms in the centroparietal area (P3) in both tasks, as well as for other auditory stimuli. The White modulation sound was the most influential, with a P3 amplitude in the spatial task in the frontal and central regions. These results suggested that the White sound during a spatial task affected the neural activation that was associated with attention accompanied with working memory activity in the N-back task.