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Main Authors: Ko, Eunyeong, Kim, Soowon, Jo, Ha-Na
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2511.07920
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author Ko, Eunyeong
Kim, Soowon
Jo, Ha-Na
author_facet Ko, Eunyeong
Kim, Soowon
Jo, Ha-Na
contents Individuals with aphasia experience severe difficulty in real-time verbal communication, while most imagined speech decoding approaches remain limited to offline analysis or computationally demanding models. To address this limitation, we propose a two-session experimental framework consisting of an offline data acquisition phase and a subsequent online feedback phase for real-time imagined speech decoding. The paradigm employed a four-class Korean-language task, including three imagined speech targets selected according to the participant's daily communicative needs and a resting-state condition, and was evaluated in a single individual with chronic anomic aphasia. Within this framework, we introduce a lightweight diffusion-based neural decoding model explicitly optimized for real-time inference, achieved through architectural simplifications such as dimensionality reduction, temporal kernel optimization, group normalization with regularization, and dual early-stopping criteria. In real-time evaluation, the proposed system achieved 65\% top-1 and 70\% top-2 accuracy, with the Water class reaching 80\% top-1 and 100\% top-2 accuracy. These results demonstrate that real-time-optimized diffusion-based architectures, combined with clinically grounded task design, can support feasible online imagined speech decoding for communication-oriented BCI applications in aphasia.
format Preprint
id arxiv_https___arxiv_org_abs_2511_07920
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Lightweight Diffusion-based Framework for Online Imagined Speech Decoding in Aphasia
Ko, Eunyeong
Kim, Soowon
Jo, Ha-Na
Artificial Intelligence
Individuals with aphasia experience severe difficulty in real-time verbal communication, while most imagined speech decoding approaches remain limited to offline analysis or computationally demanding models. To address this limitation, we propose a two-session experimental framework consisting of an offline data acquisition phase and a subsequent online feedback phase for real-time imagined speech decoding. The paradigm employed a four-class Korean-language task, including three imagined speech targets selected according to the participant's daily communicative needs and a resting-state condition, and was evaluated in a single individual with chronic anomic aphasia. Within this framework, we introduce a lightweight diffusion-based neural decoding model explicitly optimized for real-time inference, achieved through architectural simplifications such as dimensionality reduction, temporal kernel optimization, group normalization with regularization, and dual early-stopping criteria. In real-time evaluation, the proposed system achieved 65\% top-1 and 70\% top-2 accuracy, with the Water class reaching 80\% top-1 and 100\% top-2 accuracy. These results demonstrate that real-time-optimized diffusion-based architectures, combined with clinically grounded task design, can support feasible online imagined speech decoding for communication-oriented BCI applications in aphasia.
title Lightweight Diffusion-based Framework for Online Imagined Speech Decoding in Aphasia
topic Artificial Intelligence
url https://arxiv.org/abs/2511.07920