A Comparative Analysis of Retrieval-Augmented Generation Techniques for Bengali Standard-to-Dialect Machine Translation Using LLMs
K. M. Jubair Sami, Dipto Sumit, Ariyan Hossain, Farig Sadeque
Abstract
Translating from a standard language to its regional dialects is a significant NLP challenge due to scarce data and linguistic variation, a problem prominent in the Bengali language. This paper proposes and compares two novel RAG pipelines for standard-to-dialectal Bengali translation. The first, a Transcript-Based Pipeline, uses large dialect sentence contexts from audio transcripts. The second, a more effective Standardized Sentence-Pairs Pipeline, utilizes structured local_dialect:standard_bengali sentence pairs. We evaluated both pipelines across six Bengali dialects and multiple LLMs using BLEU, ChrF, WER, and BERTScore. Our findings show that the sentence-pair pipeline consistently outperforms the transcript-based one, reducing Word Error Rate (WER) from 76% to 55% for the Chittagong dialect. Critically, this RAG approach enables smaller models (e.g., Llama-3.1-8B) to outperform much larger models (e.g., GPT-OSS-120B), demonstrating that a well-designed retrieval strategy can be more crucial than model size. This work contributes an effective, fine-tuning-free solution for low-resource dialect translation, offering a practical blueprint for preserving linguistic diversity.- Anthology ID:
- 2025.banglalp-1.22
- Volume:
- Proceedings of the Second Workshop on Bangla Language Processing (BLP-2025)
- Month:
- December
- Year:
- 2025
- Address:
- Mumbai, India
- Editors:
- Firoj Alam, Sudipta Kar, Shammur Absar Chowdhury, Naeemul Hassan, Enamul Hoque Prince, Mohiuddin Tasnim, Md Rashad Al Hasan Rony, Md Tahmid Rahman Rahman
- Venues:
- BanglaLP | WS
- SIG:
- Publisher:
- Association for Computational Linguistics
- Note:
- Pages:
- 266–279
- Language:
- URL:
- https://preview.aclanthology.org/ingest-ijcnlp-aacl/2025.banglalp-1.22/
- DOI:
- Cite (ACL):
- K. M. Jubair Sami, Dipto Sumit, Ariyan Hossain, and Farig Sadeque. 2025. A Comparative Analysis of Retrieval-Augmented Generation Techniques for Bengali Standard-to-Dialect Machine Translation Using LLMs. In Proceedings of the Second Workshop on Bangla Language Processing (BLP-2025), pages 266–279, Mumbai, India. Association for Computational Linguistics.
- Cite (Informal):
- A Comparative Analysis of Retrieval-Augmented Generation Techniques for Bengali Standard-to-Dialect Machine Translation Using LLMs (Sami et al., BanglaLP 2025)
- PDF:
- https://preview.aclanthology.org/ingest-ijcnlp-aacl/2025.banglalp-1.22.pdf