StreamAlign: Streaming Text-Aligned Speech Tokenization

Kang-wook Kim, Jinyoung Park, Jinsoo Kim, Sehun Lee, Tony Woo, Gunhee Kim


Abstract
Text-aligned speech tokenization methods have emerged to better align speech tokens with LLM token spaces, enabling more effective utilization of pretrained LLMs. However, they rely on offline automatic speech recognition (ASR), leading to two key limitations: (i) the need for complete utterances before tokenization, precluding real-time streaming, and (ii) vocabulary mismatch between ASR and LLMs, which reduces acoustic granularity from the subword to the word level. We introduce StreamAlign, a text-aligned speech tokenization framework that enables streaming tokenization for real-time speech–text joint modeling. StreamAlign performs online speech–text alignment by combining character-level RNN-Transducer alignment with word-level ASR guidance, mitigating ASR–LLM vocabulary mismatch while preserving recognition accuracy. A proactive word boundary classifier anticipates word completion at chunk boundaries, reducing tokenization latency from 560ms to 270 ms. On LibriSpeech, StreamAlign achieves the lowest WER and highest UTMOS among evaluated tokenizers. Furthermore, StreamAlign-SLM, a spoken language model trained on StreamAlign units, demonstrates the strongest overall performance in terms of both acoustic and semantic consistency on the SALMon and spoken StoryCloze benchmarks.
Anthology ID:
2026.findings-emnlp.2270
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
48596–48615
Language:
URL:
https://aclanthology.org/2026.findings-emnlp.2270/
DOI:
Bibkey:
Cite (ACL):
Kang-wook Kim, Jinyoung Park, Jinsoo Kim, Sehun Lee, Tony Woo, and Gunhee Kim. 2026. StreamAlign: Streaming Text-Aligned Speech Tokenization. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 48596–48615, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
StreamAlign: Streaming Text-Aligned Speech Tokenization (Kim et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.2270.pdf