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Front. Neurosci. | doi: 10.3389/fnins.2018.00108

Improving the Performance of an Auditory Brain-Computer Interface using Virtual Sound Sources by Shortening Stimulus Onset Asynchrony

Miho Sugi1, Yutaka Hagimoto1,  Isao Nambu1*, Alejandro Gonzalez1,  Yoshinori Takei2, Shohei Yano3, Haruhide Hokari1 and  Yasuhiro Wada1
  • 1Nagaoka University of Technology, Japan
  • 2National Institute of Technology Akita College, Japan
  • 3Nagaoka National College of Technology, Japan

Recently, a brain-computer interface (BCI) using virtual sound sources has been proposed for estimating user intention via electroencephalogram (EEG) in an oddball task. However, its performance is still insufficient for practical use. In this study, we examine the impact that shortening the stimulus onset asynchrony (SOA) has on this auditory BCI. While very short SOA might improve its performance, sound perception and task performance become difficult, and event-related potentials (ERPs) may not be induced if the SOA is too short. Therefore, we carried out behavioral and EEG experiments to determine the optimal SOA. In the experiments, participants were instructed to direct attention to one of six virtual sounds (target direction). We used eight different SOA conditions: 200, 300, 400, 500, 600, 700, 800, and 1100 ms. In the behavioral experiment, we recorded participant behavioral responses to target direction and evaluated recognition performance of the stimuli. In all SOA conditions, recognition accuracy was over 85%, indicating that participants could recognize the target stimuli correctly. Next, using a silent counting task in the EEG experiment, we found significant differences between target and non-target sound directions in all but the 200-ms SOA condition. When we calculated an identification accuracy using Fisher discriminant analysis, the SOA could be shortened by 400 ms without decreasing the identification accuracies. Thus, improvements in performance (evaluated by BCI utility) could be achieved. On average, higher BCI utilities were obtained in the 400-ms and 500-ms SOA conditions. Thus, auditory BCI performance can be optimized for both behavioral and neurophysiological responses by shortening the SOA.

Keywords: Auditory BCI, SOA, EEG, P300, virtual sound

Received: 21 Nov 2017; Accepted: 12 Feb 2018.

Edited by:

Emanuel Donchin, University of South Florida, United States

Reviewed by:

Dennis J. McFarland, Wadsworth Center, United States
Natsue Yoshimura, Tokyo Institute of Technology, Japan  

Copyright: © 2018 Sugi, Hagimoto, Nambu, Gonzalez, Takei, Yano, Hokari and Wada. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Isao Nambu, Nagaoka University of Technology, Nagaoka, Japan, inambu@vos.nagaokaut.ac.jp