CodeZone Research Group at NADI 2026 Shared Task: Cross-Domain Score Calibration for Spoken Arabic Dialect Identification

Sarah Yassine, Abdulkadir Shehu Bichi


Abstract
We describe the CodeZone Research Group system for NADI 2026 Shared Task 2, spo ken Arabic dialect identification over Modern Standard Arabic and 19 country-level dialects under cross-domain evaluation. Our system ensembles an ECAPA-TDNN language identi fier fine-tuned on the shared task data with a Whisper-large-v3 dialect classifier that we fur ther adapt using waveform- and spectrogram level augmentation, fusing their log-softmax scores. This ensemble reaches 94.35% accu racy on in-domain validation but initially re tained only 25.40% on the official blind test, a collapse that affected every participating team. We show that about a fifth of this gap is a cali bration failure rather than a modelling failure: discarding per-class bias terms fit in domain raised official accuracy from 0.2540 to 0.3918 and lowered the shared task’s average cost from 0.2077 to 0.1515, and a softening temperature reduced cost further to 0.1469; neither change touched either model. Our submission ranked 10th of 16 teams, and we show analytically why uniform additive score shifts cannot affect this metric while temperature scaling can.
Anthology ID:
2026.arabicnlp-sharedtasks.9
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:
79–87
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.9/
DOI:
Bibkey:
Cite (ACL):
Sarah Yassine and Abdulkadir Shehu Bichi. 2026. CodeZone Research Group at NADI 2026 Shared Task: Cross-Domain Score Calibration for Spoken Arabic Dialect Identification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 79–87, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
CodeZone Research Group at NADI 2026 Shared Task: Cross-Domain Score Calibration for Spoken Arabic Dialect Identification (Yassine & Bichi, ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.9.pdf