Late Fusion and Multi-Level Fission Amplify Cross-Modal Transfer in Text-Speech LMs

Fuente: arXiv
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Main Authors: Cuervo, Santiago, Moumen, Adel, Labrak, Yanis, Khurana, Sameer, Laurent, Antoine, Rouvier, Mickael, Woodland, Phil, Marxer, Ricard
Format: Preprint
Published: 2025
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author Cuervo, Santiago
Moumen, Adel
Labrak, Yanis
Khurana, Sameer
Laurent, Antoine
Rouvier, Mickael
Woodland, Phil
Marxer, Ricard
author_facet Cuervo, Santiago
Moumen, Adel
Labrak, Yanis
Khurana, Sameer
Laurent, Antoine
Rouvier, Mickael
Woodland, Phil
Marxer, Ricard
contents Text-Speech Language Models (TSLMs) -- language models trained to jointly process and generate text and speech -- are commonly trained through an early modality fusion/fission approach, in which both modalities are fed and predicted from a shared backbone via linear layers. We hypothesize that this approach limits cross-modal transfer by neglecting feature compositionality -- specifically, the finer-grained nature of speech representations compared to text -- preventing the emergence of a shared feature hierarchy within model layers. In this paper, we argue that this limitation can be addressed through late fusion and fission, with a fission process that accesses both high- and low-level features for speech generation. Our models implementing these principles, SmolTolk, rival or surpass state-of-the-art TSLMs trained with orders of magnitude more compute, and achieve significantly improved cross-modal performance relative to early fusion/fission baselines. Representation analyses further suggest that our method enhances the model's ability to abstract higher-level, more semantic features from speech, and leads to increasingly shared representation spaces across layers.
format Preprint
id arxiv_https___arxiv_org_abs_2503_06211
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Late Fusion and Multi-Level Fission Amplify Cross-Modal Transfer in Text-Speech LMs
Cuervo, Santiago
Moumen, Adel
Labrak, Yanis
Khurana, Sameer
Laurent, Antoine
Rouvier, Mickael
Woodland, Phil
Marxer, Ricard
Computation and Language
Artificial Intelligence
Audio and Speech Processing
Text-Speech Language Models (TSLMs) -- language models trained to jointly process and generate text and speech -- are commonly trained through an early modality fusion/fission approach, in which both modalities are fed and predicted from a shared backbone via linear layers. We hypothesize that this approach limits cross-modal transfer by neglecting feature compositionality -- specifically, the finer-grained nature of speech representations compared to text -- preventing the emergence of a shared feature hierarchy within model layers. In this paper, we argue that this limitation can be addressed through late fusion and fission, with a fission process that accesses both high- and low-level features for speech generation. Our models implementing these principles, SmolTolk, rival or surpass state-of-the-art TSLMs trained with orders of magnitude more compute, and achieve significantly improved cross-modal performance relative to early fusion/fission baselines. Representation analyses further suggest that our method enhances the model's ability to abstract higher-level, more semantic features from speech, and leads to increasingly shared representation spaces across layers.
title Late Fusion and Multi-Level Fission Amplify Cross-Modal Transfer in Text-Speech LMs
topic Computation and Language
Artificial Intelligence
Audio and Speech Processing
url https://arxiv.org/abs/2503.06211