Abstract
Articulation imagery, a form of mental imagery, refers to the activity of imagining or speaking to oneself mentally without an articulation movement. It is an effective domain of research in speech impaired neural disorders, as speech imagination has high similarity to real voice communication. This work employs electroencephalography (EEG) signals acquired from articulation and articulation imagery in identifying the vowel being imagined during different tasks. EEG signals from chosen electrodes are decomposed using the empirical mode decomposition (EMD) method into a series of intrinsic mode functions. Brain connectivity estimators and entropy measures have been computed to analyze the functional cooperation and causal dependence between different cortical regions as well as the regularity in the signals. Using machine learning techniques such as multiclass support vector machine (MSVM) and random forest (RF), the vowels have been classified. Three different training and testing protocols (Articulation-AR, Articulation imagery-AI and Articulation vs Articulation imagery-AR vs AI) were employed for identifying the vowel being imagined of articulating. An overall classification accuracy of 80% was obtained for articulation imagery protocol which was found to be higher than the other two protocols. Also, MSVM techniques outperformed the RF technique in terms of the classification accuracy. The effect of brain connectivity estimators and machine learning techniques seems to be reliable in identifying the vowel from the subjects’ thought and thereby assisting the people with speech impairment.
Similar content being viewed by others
References
Aleman A, Van’t Wout M, (2004) Subvocalization in auditory-verbal imagery: just a form of motor imagery? Cogn Process 5(4):228–231
Amo C, de Santiago L, Barea R, Lopez-Dorado A, Boquete L (2017) Analysis of gamma band activity from human EEG using empirical mode decomposition. Sensors 17(5):989
Anderson RE (1982) Speech imagery is not always faster than visual imagery. Mem Cognit 10(4):371–380
Baccala LA, Sameshina K (1999) Using partial directed coherence to describe neuronal ensemble Interactions. J Neurosci Methods 94(1):93–103
Baccala LA, Sameshima K (2001) Partial directed coherence: a new concept in neural structure determination. Biol Cybern 84(6):463–474
Breiman L (2001) Random forests. Mach Learn 45(1):5–32
Brodmann K (2007) Brodmann’s: localisation in the cerebral cortex. Springer, New York
Callan DE, Callan AM, Honda K, Masaki S (2000) Single-sweep EEG analysis of neural processes underlying perception and production of vowels. Brain Res 10(1–2):173–176
Cortes C, Vapnik V (1995) Support vector networks. Mach Learn 20(3):273–297
Chengaiyan S, Anandhan K (2015) Analysis of speech imagery using functional and effective EEG based Brain connectivity parameters. Int J Cog Inform Nat Intell 9(4):33–48
Chengaiyan S, Retnapandian AS, Anandan K (2020) Identification of vowels in consonant–vowel–consonant words from speech imagery based EEG signals. Cogn Neurodyn 14(1):1–19
DaSalla CS, Kambara H, Sato M, Koike Y (2009) Single-trial classification of vowel speech imagery using common spatial patterns. Neural Netw 22(9):1334–1339
Dogil G, Ackermann H, Grodd W, Haider H, Kamp H, Mayer J, Riecker A, Wildgruber D (2002) The speaking brain: a tutorial introduction to fMRI experiments in the production of speech, prosody and syntax. J Neurolinguistics 15(1):59–90
Flandrin P, Goncalves P, Rilling G(2004) Detrending and denoising with Empirical Mode Decompositions. In: Proceedings of the 2004 12th European Signal Processing Conference: pp 1581–1584
Granger C (1980) Testing for causality: a personal view point. J Econ Dyn Control 2:329–352
Huang NE, Shen Z, Long SR, Wu CM, Shih HH, Zheng Q, Yen NC, Tung CC, Liu HH, (1998) The empirical mode decomposition and the Hilbert spectrum for nonlinear and non-stationary time series analysis. Proc R Soc A 454(1971):903–995
Idrees BM, Farooq O (2016) EEG based Vowel Classification during Speech Imagery. In proceedings of the 2016 In: IEEE 3rd International Conference on Computing for Sustainable Global Development (INDIACom): pp. 1130–1134
Kaminski MJ, Blinowska KJ (1991) A new method of the description of the information flow in the brain structures. Biol Cybern 65(3):203–210
Kaminski M, Ding M, Truccolo WA, Bressler SL (2001) Evaluating causal relations in neural systems: Granger causality, directed transfer function and statistical assessment of significance. Biol Cybern 85(2):145–157
Kosslyn SM (1996) Image and brain: the resolution of the imagery debate. MIT Press, Cambridge
Kumar Y, Dewal ML, Anand RS (2012) Features extraction of EEG signals using approximate and sample entropy. In: Proceedings of the 2012 IEEE Students' Conference on Electrical, Electronics and Computer Science: pp. 1–5
Liang H, Bressler SL, Desimone R, Fries P (2005) Empirical mode decomposition: a method for analyzing neural data. Neurocomputing 65:801–807
Madzarov G, Gjorgjevikj D, Chorbev I (2009) A multi-class SVM classifier utilizing binary decision tree. Informatica 33(2):233–241
Mandic DP, Rehman N, Wu Z, Huang NE (2013) Empirical mode decomposition-based time-frequency analysis of multivariate signals. IEEE Signal Process Mag 30(6):74–86
Min B, Kim J, Park HJ, Lee B (2016) Vowel imagery decoding toward silent speech BCI using extreme learning machine with electroencephalogram. Bio Med Res Int 15:1–11
Eva O, Oskar O (2013) Methodology and application of One-way ANOVA. Am J Mech Eng 1:256–261
Perrone-Bertolotti M, Rapin L, Lachaux JP, Baciu M, Loevenbruck H. (2014) What is that little voice inside my head? Inner speech phenomenology, its role in cognitive performance, and its relation to self-monitoring. Behav Brain Res 261:220–239
Pincus SM (1991) Approximate entropy as a measure of system complexity. Proc Natl Acad Sci 88(6):2297–2301
Poeppel D, Hickok G (2007) The cortical organization of speech processing. Nat Rev Neurosci 8(5):393–402
Price CJ, Crinion JT, MacSweeney MA (2011) Generative model of speech production in Broca’s and Wernicke’s areas. Front Psychol 2:237
Richman JS, Moorman JR (2000) Physiological time-series analysis using approximate entropy and sample entropy. Am J Physiol 278(6):2039–2049
Rojas DA, Ramos OL (2006) Recognition of Spanish vowels through imagined speech by using spectral analysis and SVM. J Inform Hiding Multimedia Signal Process 7:14
Sandhya C, Srinidhi G, Vaishali R, Visali M, Kavitha A(2015a) Analysis of speech imagery using brain connectivity estimators. In: Proceedings of the 2015a IEEE 14th international conference on cognitive informatics and cognitive computing (ICCCI*CC): pp 352–359
Sandhya, C; Anandha Sree R; Kavitha, A (2015b). Analysis of speech imagery using consonant-vowel syllable speech pairs and brain connectivity estimators. In: Proceedings of the 2015b 2nd international conference on biomedical systems, Signals and Images.
Sandhya C, Kavitha A (2019) Analysis of speech imagery using brain connectivity estimators on consonant-vowel-consonant words. Int J Biomed Eng Technol 30(4):329–343
Scheeren AM, Koot HM, Begeer S (2012) Social interaction style of children and adolescents with high-functioning autism spectrum disorder. J Autism Dev Disord 42(10):2046–2055
Schreiber T (2000) Measuring information transfer. Phys Rev Lett 85(2):461–464
Silchenko AN, Adamchica I, Pawelczyka N, Hauptmanna C, Maaroufb M, Sturmb V, Tassa PA (2010) Data-driven approach to the estimation of connectivity and time delays in the coupling of interacting neuronal subsystems. J Neurosci Methods 191(1):32–44
Thatcher RW, Krause PJ, Hrybyk M (1986) Cortico-cortical associations an EEG coherence: a two-compartmental model. Electroencephalogr Clin Neurophysiol 64(2):123–143
Thatcher RW, Biver CJ, North D (2004) EEG coherence and phase delays: comparisons between single reference, average reference and current source density. Neurology in Version 1, College of Medicine, University of South Florida
Tian X, Poeppel D (2010) Mental imagery of speech and movement implicates the dynamics of internal forward models. Front Psychol 1:166
Tian X, Poeppel D (2012) Mental imagery of speech: linking motor and perceptual systems through internal simulation and estimation. Front Hum Neurosci 6:314
Tian X, Zarate JM, Poeppel D (2016) Mental imagery of speech implicates two mechanisms of perceptual reactivation. Cortex 77:1–12
Ursino M, Ricci G, Magosso E (2020) Transfer entropy as a measure of brain connectivity: a critical analysis with the help of neural mass models. Front Comp Neurosci 14:45
Yoshimura N, Nishimoto A, Belkacem AN, Shin D, Kambara H, Hanakawa T, Koike Y (2016) Decoding of covert vowel articulation using electroencephalography cortical currents. Front Neurosci 10:175
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Conflict of interest
Sandhya Chengaiyan and Kavitha Anandan declare that they have no conflict of interests.
Ethical approval
Ethical approval was given by Sri Sivasubramaniya Nadar College of Engineering, Chennai, Tamil Nadu, India. This work was performed in the Department of Biomedical Engineering as per the guidelines of the Institutional Ethical Committee of SSN College of Engineering, India, for human participants.
Informed consent
Informed consent was obtained from all the individual participants included in the study.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Editor: Yan Bao (Peking University, & LMU Munich); Reviewers: Si Wu (Peking University) and a second researcher who prefers to remain anonymous.
Rights and permissions
About this article
Cite this article
Chengaiyan, S., Anandan, K. Effect of functional and effective brain connectivity in identifying vowels from articulation imagery procedures. Cogn Process 23, 593–618 (2022). https://doi.org/10.1007/s10339-022-01103-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s10339-022-01103-3