Lip-Siri: Contactless Open-Sentence Silent Speech with Wi-Fi Backscatter

Fuente: arXiv
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Main Authors: Tian, Ye, Du, Haohua, Gu, Chao, Zhang, Junyang, Wang, Shanyue, Zhou, Hao, Hou, Jiahui, Li, Xiang-Yang
Format: Preprint
Published: 2026
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author Tian, Ye
Du, Haohua
Gu, Chao
Zhang, Junyang
Wang, Shanyue
Zhou, Hao
Hou, Jiahui
Li, Xiang-Yang
author_facet Tian, Ye
Du, Haohua
Gu, Chao
Zhang, Junyang
Wang, Shanyue
Zhou, Hao
Hou, Jiahui
Li, Xiang-Yang
contents Silent speech interfaces (SSIs) enable silent interaction in noise-sensitive or privacy-sensitive settings. However, existing SSIs face practical deployment trade-offs among privacy, user experience, and energy consumption, and most remain limited to closed-set recognition over small, pre-defined vocabularies of words or sentences, which restricts real-world expressiveness. In this paper, we present Lip-Siri, to the best of our knowledge, the first Wi-Fi backscatter--based SSI that supports open-vocabulary sentence recognition via lexicon-guided subword decoding. Lip-Siri designs a frequency-shifted backscatter tag to isolate tag-modulated reflections and suppress interference from non-target motions, enabling reliable extraction of lip-motion traces from ubiquitous Wi-Fi signals. We then segment continuous traces into lip-motion units, cluster them, learn robust unit representations via cluster-based self-supervision, and finally propose a lexicon-guided Transformer encoder--decoder with beam search to decode variable-length sentence sequences. We implement an end-to-end prototype and evaluate it with 15 participants on 340 sentences and 3,398 words across multiple scenarios. Lip-Siri achieves 85.61% accuracy on word prediction and a WER of 36.87% on continuous sentence recognition, approaching the performance of representative vision-based lip-reading systems.
format Preprint
id arxiv_https___arxiv_org_abs_2601_18177
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Lip-Siri: Contactless Open-Sentence Silent Speech with Wi-Fi Backscatter
Tian, Ye
Du, Haohua
Gu, Chao
Zhang, Junyang
Wang, Shanyue
Zhou, Hao
Hou, Jiahui
Li, Xiang-Yang
Human-Computer Interaction
Silent speech interfaces (SSIs) enable silent interaction in noise-sensitive or privacy-sensitive settings. However, existing SSIs face practical deployment trade-offs among privacy, user experience, and energy consumption, and most remain limited to closed-set recognition over small, pre-defined vocabularies of words or sentences, which restricts real-world expressiveness. In this paper, we present Lip-Siri, to the best of our knowledge, the first Wi-Fi backscatter--based SSI that supports open-vocabulary sentence recognition via lexicon-guided subword decoding. Lip-Siri designs a frequency-shifted backscatter tag to isolate tag-modulated reflections and suppress interference from non-target motions, enabling reliable extraction of lip-motion traces from ubiquitous Wi-Fi signals. We then segment continuous traces into lip-motion units, cluster them, learn robust unit representations via cluster-based self-supervision, and finally propose a lexicon-guided Transformer encoder--decoder with beam search to decode variable-length sentence sequences. We implement an end-to-end prototype and evaluate it with 15 participants on 340 sentences and 3,398 words across multiple scenarios. Lip-Siri achieves 85.61% accuracy on word prediction and a WER of 36.87% on continuous sentence recognition, approaching the performance of representative vision-based lip-reading systems.
title Lip-Siri: Contactless Open-Sentence Silent Speech with Wi-Fi Backscatter
topic Human-Computer Interaction
url https://arxiv.org/abs/2601.18177