Classification (of information) Speech recognition 7 Biomedical signal processing 3 Electroencephalography 3 Electrophysiology 3 Emotion recognition 3 Feature extraction 3 Speech 3 Behavioral research 2 Bi-directional 2 Bi-directional long short-term memory 2 Binary gray wolf optimizer 2 Brain 2 Brain computer interface 2 Convolution 2 Convolutional neural networks 2 Gray wolves 2 Human communications 2 Interface states 2 Learning-based approach 2 Long short-term memory 2 Optimizers 2 Performance 2 Recognition models 2 bi-directional long short-term memory 2 binary grey wolf optimizer 2 brain–computer interface 2 electroencephalography 2 emotion recognition 2 human 2