End-to-End Vietnamese ASR with Acoustic-Aware Punctuation and Capitalization for Edge Devices
Main Article Content
Abstract
Vietnamese automatic speech recognition (ASR) for edge devices remains challenging because practical systems must simultaneously satisfy recognition accuracy, low latency, low memory overhead, and transcript readability. These requirements are particularly demanding for Vietnamese, where tonal and prosodic cues are important for sentence structuring, while many lightweight ASR systems still produce raw lowercase text without punctuation. In this work, we present an edge-ready Vietnamese ASR system built on VietASR Iteration-3 and fine-tuned on nearly 1,000 hours of professionally curated Dollya Vietnamese speech data with punctuation and capitalization annotations. Our work makes three main contributions. First, we develop a deployment-oriented fine-tuning pipeline for a compact 68M-parameter VietASR model, targeting practical offline inference on resource-constrained devices. Second, we introduce an end-to-end structured decoding formulation in which punctuation marks and capitalization indicators are incorporated directly into the output vocabulary and predicted jointly with lexical units, eliminating the need for a separate post-processing module. Third, we validate the system on both recognition and deployment aspects through evaluation on standard Vietnamese benchmarks and on a Qualcomm QCS8550 edge platform. Experimental results show that the fine-tuned model achieves 6.41% WER on the VIVOS test set, while also generating well-structured transcripts with strong punctuation performance (micro-F1 of 0.94). On the target device, the deployed system processes a 30-second utterance with about 380.0 ms encoder latency on CPU and 321.0 ms on NPU, while decoder and joiner costs remain negligible. Comparative analysis further indicates more stable Vietnamese output and better formatted transcripts than Whisper-large-v3-turbo and the pretrained VietASR baseline. These results suggest that compact Vietnamese ASR models can jointly address accuracy, formatting, and deployment constraints, making them suitable for real-time, privacy-preserving, on-device speech applications.
Keywords
Capitalization prediction, Edge AI, Punctuation restoration, RNN-T, Viet-ASR.
Article Details

This work is licensed under a Creative Commons Attribution 4.0 International License.
References
Processing: An Introduction to Natural Language
Processing, Computational Linguistics, and Speech
Recognition, with Language Models, 3rd ed., 2026.
[2] A. Gulati, J. Qin, C.-C. Chiu, N. Parmar, Y. Zhang,
J. Yu, W. Han, S. Wang, Z. Zhang, Y. Wu, et
al., Conformer: Convolution-augmented transformer for
speech recognition, arXiv preprint arXiv:2005.08100,
2020.
[3] A. Vaswani, N. Shazeer, N. Parmar, J. Uszkoreit, L.
Jones, A. N. Gomez, L. Kaiser, and I. Polosukhin,
Attention Is All You Need, CoRR, vol. abs/1706.03762,
2017.
http://arxiv.org/abs/1706.03762
[4] C. Feng, Y. Lin, S. Zhuo, C. Su, R. K. Ramakrishnan,
Z. Yuan, and X. Zhang, Edge-ASR: Towards Low-Bit
Quantization of Automatic Speech Recognition Models,
2025.
[Online] URL: https://arxiv.org/abs/2507.07877
[5] L. Do, T. N. Nguyen, T. Pham, V. Do, H. Nguyen,
and C. Nguyen, VietSuperSpeech: A Large-Scale
Vietnamese Conversational Speech Dataset for ASR
Fine-Tuning in Chatbot, Customer Support, and Call
Center Applications, 2026.
[Online] URL: https://arxiv.org/abs/2603.01894
[6] A. Jakubiak, P. Stachyra, P. Czubowski, H. Borkowski,
S. Latka, R. Izak, K. Jankowski, S. Janicka, and
M. Zielinski, Adapting ASR Models for Speech-to-
Punctuated-Text Recognition with Utterance Gluing, in
Proceedings of the 8th International Conference on
Natural Language and Speech Processing (ICNLSP-
2025), Southern Denmark University, Odense, Denmark,
Aug. 2025, pp. 72–81.
[7] O. Tilk and T. Alum¨ae, Bidirectional Recurrent Neural
Network with Attention Mechanism for Punctuation
Restoration. in Interspeech, 2016, pp. 9.
[8] T. Alam, A. Khan, and F. Alam, Punctuation restoration
using transformer models for high-and low-resource
languages, in Proceedings of the Sixth Workshop
on Noisy User-generated Text (W-NUT 2020), 2020,
pp. 132–142.
[9] H. T. T. Uyen, N. A. Tu, and T. D. Huy, Vietnamese
capitalization and punctuation recovery models, arXiv
preprint arXiv:2207.01312, 2022.
[10] A. Radford, J. W. Kim, T. Xu, G. Brockman, C.
McLeavey, and I. Sutskever, Whisper: Robust speech
recognition via large-scale weak supervision, arXiv
preprint arXiv:2212.01234, 2022.
[11] Y. Zhang, W. Han, J. Qin, Y. Wang, A. Bapna, Z. Chen,
N. Chen, B. Li, V. Axelrod, G. Wang, et al., Google
usm: Scaling automatic speech recognition beyond 100
languages, arXiv preprint arXiv:2303.01037, 2023.
[12] M. Bara´nski, J. Jasi´nski, J. Bartolewska, S. Kacprzak, M.
Witkowski, and K. Kowalczyk, Investigation of Whisper
ASR Hallucinations Induced by Non-Speech Audio, in
ICASSP 2025 - 2025 IEEE International Conference on
Acoustics, Speech and Signal Processing (ICASSP), Apr.
2025, pp. 1–5.
[13] J. Zhuo, Y. Yang, Y. Shao, Y. Xu, D. Yu, K. Yu, and
X. Chen, VietASR: Achieving Industry-level Vietnamese
ASR with 50-hour labeled data and Large-Scale Speech
Pretraining, arXiv preprint arXiv:2505.21527, 2025.
[14] W.-N. Hsu, B. Bolte, Y.-H. H. Tsai, K. Lakhotia,
R. Salakhutdinov, and A. Mohamed, Hubert: Self-
supervised speech representation learning by masked
prediction of hidden units, IEEE/ACM transactions
on audio, speech, and language processing, vol. 29,
pp. 3451–3460, 2021.
[15] A. Baevski, Y. Zhou, A. Mohamed, and M. Auli,
wav2vec 2.0: A framework for self-supervised
learning of speech representations, Advances in
neural information processing systems, vol. 33,
pp. 12449–12460, 2020.
[16] A. Graves, Sequence transduction with recurrent neural
networks, arXiv preprint arXiv:1211.3711, 2012.
[17] Z. Yao, L. Guo, X. Yang, W. Kang, F. Kuang, Y. Yang, Z.
Jin, L. Lin, and D. Povey, Zipformer: A faster and better
encoder for automatic speech recognition, arXiv preprint
arXiv:2310.11230, 2023.
[18] D. Povey, Z. Yao, F. Kuang, et al., icefall: A Modern
Open-Source Speech Recognition Toolkit, 2022.
[Online] https://github.com/k2-fsa/icefall
[19] P. ˙Zelasko, D. Povey, J. Trmal, S. Khudanpur, et
al., Lhotse: a speech data representation library for
the modern deep learning ecosystem, arXiv preprint
arXiv:2110.12561, 2021.
[20] H.-T. Luong and H.-Q. Vu, A non-expert Kaldi
recipe for Vietnamese speech recognition system,
in Proceedings of the Third International Workshop
on Worldwide Language Service Infrastructure and
Second Workshop on Open Infrastructures and Analysis
Frameworks for Human Language Technologies
(WLSI/OIAF4HLT2016), 2016, pp. 51–55.
[21] R. Ardila, M. Branson, K. Davis, M. Kohler, J. Meyer,
M. Henretty, R. Morais, L. Saunders, F. Tyers, and
G. Weber, Common Voice: A Massively-Multilingual
Speech Corpus, in Proceedings of the Twelfth Language
Resources and Evaluation conference, Marseille, France,
May 2020, pp. 4218–4222.
[22] D. Galvez, V. Bataev, H. Xu, and T. Kaldewey, Speed of
light exact greedy decoding for rnn-t speech recognition
models on gpu, arXiv preprint arXiv:2406.03791, 2024.
[23] T.-T. Le, L. T. Nguyen, and D. Q. Nguyen, PhoWhisper:
Automatic Speech Recognition for Vietnamese, in
Proceedings of the ICLR 2024 Tiny Papers track, 2024.