When Helpful Context Leaks: Privacy Risks in Domain-Adapted ASR

Fuente: arXiv
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Main Authors: Züfle, Maike, Niehues, Jan
Format: Preprint
Published: 2026
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author Züfle, Maike
Niehues, Jan
author_facet Züfle, Maike
Niehues, Jan
contents SpeechLLMs are increasingly deployed in professional settings where domain customisation is standard practice: users supply context in prompts with sensitive information, fine-tune on proprietary recordings, or both. We identify and systematically investigate an overlooked privacy risk of such customisation: a model adapted to recognise domain-specific terminology can be nudged into transcribing a phonetically similar word from its context or training data, even when a different word is spoken, thereby leaking private information. To evaluate this risk, we construct a controlled dataset and measure leakage rates across two customisation mechanisms, prompting and fine-tuning. Both mechanisms cause measurable leakage, compounding when combined. We evaluate a prompt-level mitigation strategy and analyse the accuracy-leakage trade-off across customisation approaches, finding that fine-tuning without context prompts offers the best balance. We release our code and dataset publicly.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28211
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle When Helpful Context Leaks: Privacy Risks in Domain-Adapted ASR
Züfle, Maike
Niehues, Jan
Computation and Language
SpeechLLMs are increasingly deployed in professional settings where domain customisation is standard practice: users supply context in prompts with sensitive information, fine-tune on proprietary recordings, or both. We identify and systematically investigate an overlooked privacy risk of such customisation: a model adapted to recognise domain-specific terminology can be nudged into transcribing a phonetically similar word from its context or training data, even when a different word is spoken, thereby leaking private information. To evaluate this risk, we construct a controlled dataset and measure leakage rates across two customisation mechanisms, prompting and fine-tuning. Both mechanisms cause measurable leakage, compounding when combined. We evaluate a prompt-level mitigation strategy and analyse the accuracy-leakage trade-off across customisation approaches, finding that fine-tuning without context prompts offers the best balance. We release our code and dataset publicly.
title When Helpful Context Leaks: Privacy Risks in Domain-Adapted ASR
topic Computation and Language
url https://arxiv.org/abs/2605.28211