AI-based services for inclusive language learning in immersive XR environments: Speech translation, and sign language integration

List of Authors

  1. Nikolaos D. Tantaroudas ,  
  2. Andrew J. McCracken
    ,  
  3. Ilias Karachalios
    ,  
  4. Evangelos Papatheou
Article Authors & roles Authors Peer review record Peer review Metrics
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Abstract

Background

Extended Reality (XR) technologies offer transformative potential for language education, yet current platforms largely neglect the accessibility needs of deaf and hard-of-hearing individuals. Existing solutions typically operate in single-language environments and lack integrated support for sign language and multimodal communication. There is a critical need for inclusive platforms that serve both deaf and hearing learners through cross-modal AI services embedded in immersive environments.

Methods

This study presents a modular platform integrating six AI services: speech-to-text transcription (OpenAI Whisper), multilingual translation (Meta NLLB), text-to-speech synthesis (AWS Polly), sentiment analysis (RoBERTa), session summarisation (flan-t5-base-samsum), and International Sign (IS) translation via Google MediaPipe. An IS dataset of 750 gesture videos was processed to extract hand landmark coordinates mapped to 3D avatar animations within a Unity-based VR environment on Meta Quest 3 headsets. The system was validated through technical benchmarking of AI service performance, including comparative evaluation of text-to-speech services and multilingual translation models (NLLB-200 and EuroLLM 1.7B variants), load testing to assess platform. scalability, and end-to-end pipeline latency measurement for both the hearing and the deaf user pathways. The educational scenario was additionally evaluated in a companion pilot study, 50 which shares the same underlying AI services and provides complementary user-perception evidence.

Results

Technical benchmarking confirmed the platform’s viability for real-time XR deployment. TTS benchmarking confirmed AWS Polly’s lowest latency (50–100 ms first byte) at competitive cost. The EuroLLM 1.7B Instruct model achieved a BLEU score of 84.34, outperforming NLLB’s 79.25. Load testing with 1,000 simulated concurrent users demonstrated average response times under 800 milliseconds with no critical failures. Avatar animation latency for IS sign rendering remained consistently under 300 milliseconds. End-to-end pipeline latency averaged 2.05 ± 0.31 s for the hearing pathway and 2.32 ± 0.34 s for the deaf (IS) pathway, both within accepted thresholds for conversational educational use. The companion pilot (N = 10) reported a mean overall experience rating of 4.6/5.0, 92% user satisfaction and unanimous (100%) demand for expanded language and sign-language support. 50

Conclusions

The results presented in this study focus on the technical feasibility of integrating cross-modal AI services within XR environments for accessible, multilingual language learning. The modular architecture enables independent scaling and adaptation to diverse contexts, laying the groundwork for equitable educational solutions aligned with EU digital accessibility objectives.

Plain Language Summary

Learning a new language can be challenging, and it is even more difficult for deaf individuals who rely on sign language. This study addresses the challenge by creating a virtual reality (VR) learning environment where a digital 3D character (avatar) can speak, translate, and perform sign language in real time. The system uses several artificial intelligence tools working together: one that converts speech into text, another that translates text between multiple languages, a third that converts text back into spoken language, and a fourth that translates text into International Sign Language gestures performed by the avatar. Users wear a VR headset and interact with the avatar in a virtual classroom where they can select their preferred language and receive immediate translations in both spoken and signed forms. The system’s technical performance was validated through benchmarking of AI translation models, text-to-speech services, end-to-end pipeline latency measurement, and scalability testing, confirming its suitability for real-time educational applications. Complementary user feedback gathered in a companion pilot study, which uses the same underlying AI services, is cross-referenced where relevant. 50 This research is a step toward creating virtual learning environments where language barriers and hearing limitations no longer prevent people from accessing education.

Corresponding author
Nikolaos D. Tantaroudas
0000-0001-6727-1014
Grant information

This research was supported by FSTP Funding from the European Union's Horizon Europe Research and Innovation programme under grant agreement No. 101070631 (UTTER — Unified Transcription and Translation for Extended Reality) and from the UK Research and Innovation (UKRI) under the UK government's Horizon Europe funding guarantee (Grant No. 10039436). Views and opinions expressed are those of the authors only and do not necessarily reflect those of the European Union nor the granting authority. Neither the European Union nor the granting authority can be held responsible for them. The funding body had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Copyright
© 2026 Nikolaos D. Tantaroudas (Corresponding Author, Co-Author); Andrew J. McCracken (Co-Author); Ilias Karachalios (Co-Author); Evangelos Papatheou (Co-Author) Creative Commons License

This work is licensed under a Creative Commons Attribution 4.0 International License.

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Amendment

Thirys second version of the article (v4) responds directly to   the peer-review feedback received on v1/v3 and substantially strengthens the scientific validation, reproducibility, and positioning of the work. The paper is now explicitly framed as a system demonstration and technical feasibility study rather than a learning-effectiveness trial. Four substantive technical additions have been incorporated: (i) a new Methodology subsection Dataset Preparation and Preprocessing describing the 750-clip International Sign corpus in detail (frame rate, landmark normalisation, missing-detection handling, and 80/10/10 train/validation/test split with fixed random seed); (ii) a new subsection Recognition Model and Training documenting the hybrid dictionary-lookup plus two-layer BiLSTM classifier (architecture, optimiser, learning rate, batch size, early stopping, and held-out top-1/top-5/F1-macro results); (iii) a new Results subsection End-to-End Pipeline Latency Analysis reporting per-stage and total wall-clock latency over 200 utterances for both the hearing pathway (2.05 ± 0.31 s) and the deaf/IS pathway (2.32 ± 0.34 s); and (iv) expanded methodology for the TTS and NLLB-vs-EuroLLM benchmarks (utterance counts, repetitions, configuration, and explicit acknowledgement of the small 10-sentence translation as a limitation). Complementary user-perception evidence from the related pilot study, published separately in Open Research Europe under independent ethical approval, is now cross-referenced where directly relevant.

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Authors & roles

Nikolaos D. Tantaroudas

Institute of Communications and Computer Systems (ICCS), Iroon Polytechneiou 9,Zografou, Athens, 15773, Greece

Roles
Corresponding Author, Co-Author, Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Investigation, Methodology, Software, Supervision, Validation, Writing – Original Draft Preparation, Writing – Review & Editing
0000-0001-6727-1014

Andrew J. McCracken

DASKALOS-APPS, PERONNAS, 01960, France

Roles
Co-Author, Conceptualization, Data Curation, Formal Analysis, Funding Acquisition, Methodology, Project Administration, Software, Writing – Review & Editing

Ilias Karachalios

National Technical University of Athens, Zografou, Attica, Greece

Roles
Co-Author, Investigation, Methodology, Resources, Validation, Visualization, Writing – Review & Editing

Evangelos Papatheou

Small-Scale Robotics Laboratory, University of Exeter Engineering, Exeter, England, EX4 4QF, UK

Roles
Co-Author, Conceptualization, Data Curation, Investigation, Methodology, Resources, Supervision, Validation, Writing – Review & Editing

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