A hybrid LLM-augmented Bangla text normalization framework for text-to-speech.
Kingfisher is a three-stage hybrid Bangla text normalization framework for Text-to-Speech, combining LLM-based tokenization and semiotic class annotation, lexicon-driven context-aware verbalization, and automated error correction.
It achieves 96% overall accuracy (95% CI: 95-97%) across diverse Bangla texts, outperforming Sparrowhawk, the only previously available Bangla normalizer. Kingfisher is released together with the first public Bangla text normalization dataset.
Text normalization (TN), the process of converting non-standard words into their spoken equivalents, is a fundamental pre-processing step for text-to-speech (TTS) systems. While substantial progress has been made in TN for well-resourced languages, low-resource languages such as Bangla have received limited attention. We present Kingfisher, a three-stage hybrid framework combining LLM-based tokenization and semiotic class annotation, lexicon-driven context-aware verbalization, and error correction to build an accurate Bangla text normalizer. Experimental evaluations across diverse Bangla texts demonstrate that Kingfisher achieves superior performance, with an overall accuracy of 96% (confidence interval 95%–97%), significantly outperforming the only publicly available Bangla text normalizer, Sparrowhawk. To support further research, we release the Bangla text normalization dataset and make the source code of the text normalization system publicly available11https://github.com/Rajan-sust/BanglaTextNorm, offering a substantial contribution to the Bangla speech technology community.
@article{kingfisher2026,title={Kingfisher: A hybrid LLM-augmented Bangla text normalization for enhanced text-to-speech},journal={Natural Language Processing Journal},volume={14},pages={100201},year={2026},issn={2949-7191},doi={https://doi.org/10.1016/j.nlp.2026.100201},url={https://www.sciencedirect.com/science/article/pii/S2949719126000051},author={Raju, Rajan Saha and Ahmad, Arif and Rahman, Mohammad Shahidur},keywords={Text normalization, Text-to-speech (TTS), Bangla, Large language model (LLM)},}