NAMAA Community at NADI 2026: Mixed-Dialect and Code-Switched Arabic ASR and Spoken Dialect Identification

Mohamed Abdelaziz, Fatimah Mohamed Emad Elden, Mousa Ashraf Abd El Malak, Omer Nacar


Abstract
Robust Arabic speech processing must accommodate dialectal variation, multilingual code-switching, and distribution shift. We present NAMAA Community’s systems for three NADI 2026 speech subtasks: Mixed-Dialect Arabic ASR, Code-Switched Arabic ASR, and 20-way Spoken Arabic Dialect Identification. For Mixed-Dialect ASR, an Arabic-specific Conformer–Transformer achieves 0.45 word error rate (WER) on the blind set, outperforming a development-selected normalization and consensus pipeline at 0.49. For Code-Switched ASR, two-stage LoRA adaptation of the Tunisian Whisper-derived FarukSTT checkpoint, with multilingual tokenization and unconstrained decoding, yields 20.38% WER and 8.06% character error rate (CER) on validation and 16.98% blind-test WER. For dialect identification, a four-model ensemble reaches 0.950 development accuracy but 0.31 on the out-of-domain blind set. Label-free class-spread and inter-model agreement diagnostics identify an outlying component; removing it improves blind accuracy to 0.36, and a refined three-model submission reaches 0.38. Across Subtasks 1.2 and 2, development-selected calibration did not reliably transfer to blind data, although the available comparisons do not isolate the causal effect of individual components.
Anthology ID:
2026.arabicnlp-sharedtasks.7
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:
63–71
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.7/
DOI:
Bibkey:
Cite (ACL):
Mohamed Abdelaziz, Fatimah Mohamed Emad Elden, Mousa Ashraf Abd El Malak, and Omer Nacar. 2026. NAMAA Community at NADI 2026: Mixed-Dialect and Code-Switched Arabic ASR and Spoken Dialect Identification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 63–71, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
NAMAA Community at NADI 2026: Mixed-Dialect and Code-Switched Arabic ASR and Spoken Dialect Identification (Abdelaziz et al., ArabicNLP 2026)
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PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.7.pdf