PogranichnyZashchitnik at ArA-DF 2026: WavLM Large with LoRA and One-Class Softmax for Arabic Speech Deepfake Detection

Minh-Hoang Le


Abstract
This paper describes the system submitted by team PogranichnyZashchitnik to the ArA-DF 2026 shared task on Arabic Audio Deepfake Detection. We build on WavLM Large as a self-supervised feature extractor, fine-tuned with Low-Rank Adaptation (LoRA) so that only a small fraction of parameters need updating. Representations from all 25 hidden layers are blended via a learnable weighted sum, pooled into utterance-level embeddings with Attentive Statistics Pooling, and classified by an OC-Softmax head that treats bonafide speech as the target class. Combined with an augmentation pipeline of codec compression, additive noise, and reverberation, this single system achieves 12.54% EER on Track 1 (Dialect Generalization, 14th/15) and 5.66% EER on Track 2 (Acoustic Robustness, 8th/14), outperforming the organizer baseline on both tracks. Post-evaluation analysis shows that utterances shorter than two seconds are disproportionately difficult, and that a non-trivial fraction of spoofed samples are scored as confidently bonafide under dialect mismatch.
Anthology ID:
2026.arabicnlp-sharedtasks.191
Volume:
Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Muhammad Abdul-Mageed, Tamer Elsayed, Houda Bouamor, Samhaa El-Beltagy, Hend Al-Khalifa, Ahmed Abdelali, AbdelRahim Elmadany, Abdellah El Mekki, Kareem Darwish, Sakhar Alkhereyf, Hamzah Luqman, Salam Khalifa, Samar Magdy, Zaid Alyafeai, Injy Hamed, Wajdi Zaghouani, Imed Zitouni
Venue:
ArabicNLP
SIG:
SIGARAB
Publisher:
Association for Computational Linguistics
Note:
Pages:
1491–1495
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.191/
DOI:
Bibkey:
Cite (ACL):
Minh-Hoang Le. 2026. PogranichnyZashchitnik at ArA-DF 2026: WavLM Large with LoRA and One-Class Softmax for Arabic Speech Deepfake Detection. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 1491–1495, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
PogranichnyZashchitnik at ArA-DF 2026: WavLM Large with LoRA and One-Class Softmax for Arabic Speech Deepfake Detection (Le, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.191.pdf