Reducing Prompt Sensitivity in LLM-based Speech Recognition Through Learnable Projection

Fuente: arXiv
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Auteurs principaux: Burdisso, Sergio, Villatoro-Tello, Esaú, Kumar, Shashi, Madikeri, Srikanth, Carofilis, Andrés, Rangappa, Pradeep, E, Manjunath K, Hacioglu, Kadri, Motlicek, Petr, Stolcke, Andreas
Format: Preprint
Publié: 2026
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author Burdisso, Sergio
Villatoro-Tello, Esaú
Kumar, Shashi
Madikeri, Srikanth
Carofilis, Andrés
Rangappa, Pradeep
E, Manjunath K
Hacioglu, Kadri
Motlicek, Petr
Stolcke, Andreas
author_facet Burdisso, Sergio
Villatoro-Tello, Esaú
Kumar, Shashi
Madikeri, Srikanth
Carofilis, Andrés
Rangappa, Pradeep
E, Manjunath K
Hacioglu, Kadri
Motlicek, Petr
Stolcke, Andreas
contents LLM-based automatic speech recognition (ASR), a well-established approach, connects speech foundation models to large language models (LLMs) through a speech-to-LLM projector, yielding promising results. A common design choice in these architectures is the use of a fixed, manually defined prompt during both training and inference. This setup not only enables applicability across a range of practical scenarios, but also helps maximize model performance. However, the impact of prompt design remains underexplored. This paper presents a comprehensive analysis of commonly used prompts across diverse datasets, showing that prompt choice significantly affects ASR performance and introduces instability, with no single prompt performing best across all cases. Inspired by the speech-to-LLM projector, we propose a prompt projector module, a simple, model-agnostic extension that learns to project prompt embeddings to more effective regions of the LLM input space, without modifying the underlying LLM-based ASR model. Experiments on four datasets show that the addition of a prompt projector consistently improves performance, reduces variability, and outperforms the best manually selected prompts.
format Preprint
id arxiv_https___arxiv_org_abs_2601_20898
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Reducing Prompt Sensitivity in LLM-based Speech Recognition Through Learnable Projection
Burdisso, Sergio
Villatoro-Tello, Esaú
Kumar, Shashi
Madikeri, Srikanth
Carofilis, Andrés
Rangappa, Pradeep
E, Manjunath K
Hacioglu, Kadri
Motlicek, Petr
Stolcke, Andreas
Audio and Speech Processing
Computation and Language
Machine Learning
LLM-based automatic speech recognition (ASR), a well-established approach, connects speech foundation models to large language models (LLMs) through a speech-to-LLM projector, yielding promising results. A common design choice in these architectures is the use of a fixed, manually defined prompt during both training and inference. This setup not only enables applicability across a range of practical scenarios, but also helps maximize model performance. However, the impact of prompt design remains underexplored. This paper presents a comprehensive analysis of commonly used prompts across diverse datasets, showing that prompt choice significantly affects ASR performance and introduces instability, with no single prompt performing best across all cases. Inspired by the speech-to-LLM projector, we propose a prompt projector module, a simple, model-agnostic extension that learns to project prompt embeddings to more effective regions of the LLM input space, without modifying the underlying LLM-based ASR model. Experiments on four datasets show that the addition of a prompt projector consistently improves performance, reduces variability, and outperforms the best manually selected prompts.
title Reducing Prompt Sensitivity in LLM-based Speech Recognition Through Learnable Projection
topic Audio and Speech Processing
Computation and Language
Machine Learning
url https://arxiv.org/abs/2601.20898