Beyond Clean Text: Evaluating Encoder and Decoder Robustness for Bangla Event Detection in Noisy Text
This study evaluates the robustness of Bangla event detection systems in real-world noisy conditions by introducing a benchmark of 9,979 annotated sentences across 40 event subtypes, including clean text, ASR transcripts, and orthographically corrupted text. Results show a trade-off: encoder models excel on clean text but degrade under noise, while decoder-only LLMs are more robust. Instruction tuning with annotation guidelines improves baseline performance on noise but not consistently. Model scaling boosts decoder robustness, and mixed training narrows the robustness gap, especially benefiting encoders.
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[Submitted on 29 Jun 2026]
Title:Beyond Clean Text: Evaluating Encoder and Decoder Robustness for Bangla Event Detection in Noisy Text
View a PDF of the paper titled Beyond Clean Text: Evaluating Encoder and Decoder Robustness for Bangla Event Detection in Noisy Text, by Tanvir Ahmed Sijan and 3 other authors
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Abstract:Event detection (ED) systems are typically evaluated on clean, curated text, leaving their robustness to real-world noise largely unexplored, particularly for low-resource languages such as Bangla. We introduce a generalized Bangla news event ontology and a benchmark comprising 9,979 annotated sentences across 40 event subtypes, spanning clean news text, real-world Automatic Speech Recognition (ASR) transcripts, and orthographically corrupted text. We systematically evaluate fine-tuned encoder-only models (BanglaBERT and XLM-R) alongside instruction-tuned decoder-only large language models (Llama 3 and Gemma 3). Our results reveal a clear architectural trade-off: encoder models achieve higher performance on clean text but degrade substantially under noise, whereas decoder-only LLMs are markedly more robust, particularly when event triggers are corrupted. We further show that embedding annotation guidelines during instruction tuning establishes a higher performance baseline on noisy text but yields inconsistent reductions in performance degradation across noisy conditions. Finally, model scaling consistently improves the robustness of decoder-only LLMs, while combined training on clean and noisy data serves as an effective regularization strategy that disproportionately benefits encoder architectures, significantly narrowing the robustness gap.
Comments: 17 pages, 8 figures
Subjects:
Computation and Language (cs.CL)
Cite as: arXiv:2606.30914 [cs.CL]
(or arXiv:2606.30914v1 [cs.CL] for this version)
https://doi.org/10.48550/arXiv.2606.30914
arXiv-issued DOI via DataCite (pending registration)
Submission history
From: Tanvir Ahmed Sijan [view email] [v1] Mon, 29 Jun 2026 21:03:32 UTC (2,793 KB)
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