Iranian Journal of Biomedical Engineering (IJBME)
نشریه علمی مهندسی پزشکی زیستی

Persian speller based on hybrid SSVEP and Triple RSVP paradigm

Document Type : Full Research Paper

Authors

Fatemeh Javaheri 1
Mohammad Bagher Khodabakhshi 2
Rasool Baghbani 1

1 Department of Medical Engineering, Hamedan University of Technology, Hamedan, Iran

2 Department of Biomedical Engineering, Hamedan University of Technology

https://doi.org/10.22041/ijbme.2025.2052353.1958
Abstract
Brain-Computer Interface (BCI) offers a communication pathway for individuals with severe disabilities, enabling them to spell words using brain activity. This study proposes a combined BCI system using Rapid Serial Visual Presentation (RSVP) and Steady-State Visual Evoked Potential (SSVEP) to enhance spelling accuracy and speed. The system organizes 36 characters into 3 groups of 12, each further divided into 4 subgroups of 3 characters. Each subgroup is arranged around a flashing square. SSVEP assigns unique frequencies to identify target groups, while triadic RSVP identifies subgroups. The target character is determined using single-frequency SSVEP.



Power Spectral Density Analysis (PSDA) detects SSVEP frequencies, and wavelet transform with Support Vector Machine (SVM) identifies P300 components in RSVP. Canonical Correlation Analysis (CCA) extracts features for a nonlinear SVM classifier in single-frequency SSVEP. The system was tested on 7 healthy participants, achieving 91.2% accuracy and an Information Transfer Rate (ITR) of 21.5 bits/min. Reducing SSVEP stimulation to 4 seconds maintained accuracy at 90.5% and increased ITR to 25.37 bits/min. Using Persian letters and more characters improved ITR while maintaining accuracy and reducing spelling time compared to similar studies.

Keywords

Speller
Brain and computer interface
Event-dependent potential
Steady state visual evoked potential
Visual presentation of fast serial

Subjects

Iranian Journal of Biomedical Engineering (IJBME)
Volume 18, Issue 3
Autumn 2024
Pages 273-287

  • Receive Date 02 February 2025
  • Revise Date 11 May 2025
  • Accept Date 14 May 2025

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