Communication Aid Based on Event Related Brain Potentials for Auditory Stimulus

作为开发残疾人交流辅助人机界面的基础，我们研究了P300组件在通过说话者随机顺序选择一个单词时的行为。选词实验的听觉刺激采用5个词。目标词被随机使用的概率为20%。受试者被要求在心里数目标单词的数量。P300分量通过以下方法得到：1)中心频率为3hz的带通滤波，2)对每个刺激的单次试验反应平均30次，3)减去目标刺激和非目标刺激的ERP反应中的共同分量，4)使用梯形时间窗切割P300。结果表明，P300成分可以在没有任何物理动作的情况下检测受试者的注意力。然而，正确的单词被选中的比例约为60%。未来的工作需要更多的实验来提高这一比例。

As a basis to develop a human interface for communication aids for the handicapped, we conducted a study on the behavior of P300 components for selecting one of the words presented through a speaker in a random sequence. For the auditory stimulus of the word-selecting experiments, 5 words were used. The target word was randomly applied with a probability of 20 %. The subject was instructed to keep a mental count of the number of target words. The P300 components were obtained from the target responses by means of the following methods : 1) Band-pass filtering of the central frequency of 3 Hz, 2) Averaging the single-trial responses to each stimulus 30 times, 3) Subtracting the common components in ERP responses for both target stimuli and non-target stimuli, and 4) Cutting out the P300 using the time-window of the trapezoidal form. Results show that the P300 component can be used to detect the attention of the subject without any physical action. However, right words were selected in a percentage of about 60 %. More experiments will be needed for future work to improve the percentage.