Improving Urdu ASR with Fine-Tuned Small Language Models for Post-ASR Error Correction

Sajjad Haider, Solat J. Sheikh, Zuha Aqib, Farah Inayat, Zehra Ahmed


Abstract
Current multilingual automatic speech recognition (ASR) models have substantially improved speech recognition across many languages, yet recognition quality remains limited for low-resource languages such as Urdu. A common approach to improve recognition quality is to fine-tune the ASR model itself, but this requires labelled speech data and retraining the recognizer. A recently emerging alternative is Generative Error Correction (GEC), in which a language model post-processes ASR output to correct transcription errors while leaving the underlying speech recognizer unchanged. This paper investigates this approach for Urdu by keeping Whisper-Turbo frozen and fine-tuning small language models to correct its transcription errors. To address data scarcity in Urdu, we construct a pseudo-gold training dataset using a strong teacher model. Fine-tuning 3.5–4B parameter language models on this data achieves a ~33% relative WER reduction (from 11.74% to 7.81%), outperforming zero-shot baselines as well as significantly larger 12–14B zero-shot models. These results show that combining a frozen recognizer with a small fine-tuned corrector provides a practical, resource-efficient framework for Urdu ASR improvement without relying on ASR retraining or substantially larger models.
Anthology ID:
2026.salma-1.7
Volume:
The Proceedings of Speech and Audio Language Models Workshop (2nd Edition)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Santosh T.Y.S.S., Sreyan Ghosh, Ramani Duraiswami, Shinji Watanabe, Siddhant Arora, Sonal Kumar, Yossi Adi, Dinesh Manocha, Leibny Paola Garcia Perera
Venues:
SALMA | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
74–84
Language:
URL:
https://aclanthology.org/2026.salma-1.7/
DOI:
Bibkey:
Cite (ACL):
Sajjad Haider, Solat J. Sheikh, Zuha Aqib, Farah Inayat, and Zehra Ahmed. 2026. Improving Urdu ASR with Fine-Tuned Small Language Models for Post-ASR Error Correction. In The Proceedings of Speech and Audio Language Models Workshop (2nd Edition), pages 74–84, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Improving Urdu ASR with Fine-Tuned Small Language Models for Post-ASR Error Correction (Haider et al., SALMA 2026)
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PDF:
https://aclanthology.org/2026.salma-1.7.pdf