SPES: Spectrogram Perturbation for Explainable Speech-to-Text Generation

Dennis Fucci, Marco Gaido, Beatrice Savoldi, Matteo Negri, Mauro Cettolo, Luisa Bentivogli


Abstract
Spurred by the demand for interpretable models, research on explainable AI for language technologies has experienced significant growth, with feature attribution methods emerging as a cornerstone of this progress. While prior work in NLP explored such methods for classification tasks and textual applications, explainability intersecting generation and speech is lagging, with existing techniques failing to account for the autoregressive nature of state-of-the-art models and to provide finegrained, phonetically meaningful explanations. We address this gap by introducing Spectrogram Perturbation for Explainable Speech-to-text Generation (SPES), a feature attribution technique applicable to sequence generation tasks with autoregressive models. SPES provides explanations for each predicted token based on both the input spectrogram and the previously generated tokens. Extensive evaluation on speech recognition and translation demonstrates that SPES generates explanations that are faithful and plausible to humans.
Anthology ID:
2026.tacl-1.35
Volume:
Transactions of the Association for Computational Linguistics, Volume 14
Month:
Year:
2026
Address:
Cambridge, MA
Venue:
TACL
SIG:
Publisher:
MIT Press
Note:
Pages:
772–801
Language:
URL:
https://aclanthology.org/2026.tacl-1.35/
DOI:
10.1162/tacl.a.684
Bibkey:
Cite (ACL):
Dennis Fucci, Marco Gaido, Beatrice Savoldi, Matteo Negri, Mauro Cettolo, and Luisa Bentivogli. 2026. SPES: Spectrogram Perturbation for Explainable Speech-to-Text Generation. Transactions of the Association for Computational Linguistics, 14:772–801.
Cite (Informal):
SPES: Spectrogram Perturbation for Explainable Speech-to-Text Generation (Fucci et al., TACL 2026)
Copy Citation:
PDF:
https://aclanthology.org/2026.tacl-1.35.pdf