Lost in Speech: Trilingual Spoken Hallucination Detection Across Audio and Transcripts

Meruyert Aristombayeva, Jason S Lucas, Chaewan Chun, Dongwon Lee


Abstract
While text-based hallucination detection is well studied, reference-free detection of factual alterations in speech remains underexplored, especially for low-resource languages. Our spoken benchmark comprises 12,013 English, Russian, and Kazakh news samples with three synthetic alteration types and three severity levels, pairing source articles with rewrites as text, synthesized audio, and ASR transcripts. We add 290 fact-checked misinformation items collected in Russian (225) and Kazakh (65), translated into the other language and rendered through the same TTS–ASR pipeline. We evaluate fine-tuned multilingual encoders and zero-shot multimodal decoders on text, transcripts, and audio. Detectors receive only target inputs without source articles or external evidence; the task evaluates reference-free classification rather than evidence-grounded verification. Encoder degradation from source text to transcripts generally tracks per-language ASR error on the binary task. Among decoders, only Gemma-3n exceeds the binary majority-class baseline in macro-F1, on transcripts only; the other four do not exceed their respective baselines. Comparisons between audio and transcripts are confounded by differences in evaluation coverage and class balance. Synthetic-trained detectors achieve 0.82–0.88 macro-F1 on real-world misinformation source text; Russian provenance analysis reveals veracity-related and model-dependent machine-style signals, a key confound in synthetic hallucination benchmarks.
Anthology ID:
2026.salma-1.6
Volume:
The Proceedings of Speech and Audio Language Models Workshop (2nd Edition)
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Santosh T.Y.S.S., Sreyan Ghosh, Ramani Duraiswami, Shinji Watanabe, Siddhant Arora, Sonal Kumar, Yossi Adi, Dinesh Manocha, Leibny Paola Garcia Perera
Venues:
SALMA | WS
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
53–73
Language:
URL:
https://aclanthology.org/2026.salma-1.6/
DOI:
Bibkey:
Cite (ACL):
Meruyert Aristombayeva, Jason S Lucas, Chaewan Chun, and Dongwon Lee. 2026. Lost in Speech: Trilingual Spoken Hallucination Detection Across Audio and Transcripts. In The Proceedings of Speech and Audio Language Models Workshop (2nd Edition), pages 53–73, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Lost in Speech: Trilingual Spoken Hallucination Detection Across Audio and Transcripts (Aristombayeva et al., SALMA 2026)
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PDF:
https://aclanthology.org/2026.salma-1.6.pdf