Thakaa at NADI 2026 Shared Task: ROVER Ensembling and Multi-Representation Fusion for Robust Arabic ASR and Dialect Identification

Abdulaziz Otaif, Hazem Bakhshwain, Abdulhamid Aldoobi, Meshal Alamr, Abdullah Aldahlawi


Abstract
We describe Thakaa’s systems for NADI 2026 subtasks 1.1 and 1.3 and Task 2, covering noisy country-level Arabic automatic speech recognition (ASR), Tunisian code-switched ASR, and spoken dialect identification. The ASR systems combine heterogeneous connectionist temporal classification (CTC), encoder–decoder, and audio-LLM recognizers through ROVER, with country-aware routing for subtask 1.1 and a frame-rate-corrected CTC anchor for subtask 1.3. The dialect identifier fuses Ara-BEST-RQ acoustic scores with lexical evidence extracted from Cohere and Whisper transcripts by a partially fine-tuned MARBERTv2 model. Our official test scores were 50.41% WER on subtask 1.1, 14.53% WER on subtask 1.3, and 56.15% accuracy on Task 2, ranking third, third, and first, respectively. Across the three systems, the largest gains came from explicit control of alignment, temporal resolution, and evidence diversity rather than from model scale alone.
Anthology ID:
2026.arabicnlp-sharedtasks.11
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:
95–109
Language:
URL:
https://aclanthology.org/2026.arabicnlp-sharedtasks.11/
DOI:
Bibkey:
Cite (ACL):
Abdulaziz Otaif, Hazem Bakhshwain, Abdulhamid Aldoobi, Meshal Alamr, and Abdullah Aldahlawi. 2026. Thakaa at NADI 2026 Shared Task: ROVER Ensembling and Multi-Representation Fusion for Robust Arabic ASR and Dialect Identification. In Proceedings of The Fourth Arabic Natural Language Processing Conference: Shared Tasks, pages 95–109, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Thakaa at NADI 2026 Shared Task: ROVER Ensembling and Multi-Representation Fusion for Robust Arabic ASR and Dialect Identification (Otaif et al., ArabicNLP 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.arabicnlp-sharedtasks.11.pdf