Reasearch On Auditory Brain Computer Interface Based On Dichotic Listening Paradigm

Brain Computer Interface (BCI) is a communication system established between thebrain and external devices like computers, which controls external device throughextracting the signals of brain activities directly rather than relying on the normal outputchannel of the brain. Great achievements have been made in the large amount of researcheson BCI based on visual paradigm both domestically and abroad. However, the visual abilityof patients who lost autonomous control of their muscle will decline relatively at the sametime. BCI on visual paradigm system can hardly function well. Fortunately, for most of thelocked-in patients, their auditory system still works well. Therefore, we can improve theirliving through auditory BCI.In this thesis, the dichotic listening experiment was brought into the field of BCI onthe basis of auditory physiological mechanism study. We carried out the research onauditory BCI based on dichotic listening paradigm. The main contributions in this thesishave been listed as below:1. Three tasks based on dichotic listening paradigm were designed. Different soundstimulation sequences were presented to both ears of the subject, and the subject made achoice by focusing on the sound sequence from one ear.2. Coherent average was used to extract features. Features of N200and P300anddifferent waveform N2ac appear in target stimulus waveform. The effect of stimulusfrequency, target stimulus frequency and the position of electrodes on auditory evokedpotential had been explored through the comparison of the three experimental tasks.3. Support vector machine (SVM) method was used to assess the target detectionaccuracy. The classification accuracy of combining N200and P300together was higherthan P300only. We found that when target stimulus frequency decreased, the accuracy ofclassification would go up while the rate of information transmission would go down. Theclassification accuracy based on multiple electrodes was higher than a single electrode. Theclassification accuracy of featured electrode of the six test subjects and those based onmulti-electrode features both reached over80%, which proved the effectiveness andfeasibility of dichotic listening paradigm.4. The on-line system based on auditory BCI was designed according to the basicdaily need of patients. In order to satisfy online BCI system’s needs for real-time, a soundwas added respectively in the sound sequence of both left ear and right ear, and the kinds ofchoice would be increased. All the six subjects could control the BCI system based ondichotic listening paradigm online through training.