A Novel Deep Learning Architecture for Decoding Imagined Speech from EEG

TL;DR

This paper introduces a novel deep neural network architecture for decoding imagined speech from EEG signals, achieving competitive accuracy by selecting optimal channels and using feature extraction techniques, addressing data scarcity issues.

Contribution

The paper presents the first use of DNN for classifying imagined speech from EEG, utilizing channel selection and feature extraction to improve decoding accuracy.

Findings

Achieved accuracy comparable to state-of-the-art methods.

Selected nine EEG channels using CSP for optimal cortical activity capture.

Demonstrated potential for further improvements with higher-density EEG and advanced deep learning models.

Abstract

The recent advances in the field of deep learning have not been fully utilised for decoding imagined speech primarily because of the unavailability of sufficient training samples to train a deep network. In this paper, we present a novel architecture that employs deep neural network (DNN) for classifying the words "in" and "cooperate" from the corresponding EEG signals in the ASU imagined speech dataset. Nine EEG channels, which best capture the underlying cortical activity, are chosen using common spatial pattern (CSP) and are treated as independent data vectors. Discrete wavelet transform (DWT) is used for feature extraction. To the best of our knowledge, so far DNN has not been employed as a classifier in decoding imagined speech. Treating the selected EEG channels corresponding to each imagined word as independent data vectors helps in providing sufficient number of samples to train a DNN. For each test trial, the final class label is obtained by applying a majority voting on the classification results of the individual channels considered in the trial. We have achieved accuracies comparable to the state-of-the-art results. The results can be further improved by using a higher-density EEG acquisition system in conjunction with other deep learning techniques such as long short-term memory.