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Main Authors: Wang, Dingdong, Li, Junan, Cui, Mingyu, Yang, Dongchao, Chen, Xueyuan, Meng, Helen
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2508.17863
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author Wang, Dingdong
Li, Junan
Cui, Mingyu
Yang, Dongchao
Chen, Xueyuan
Meng, Helen
author_facet Wang, Dingdong
Li, Junan
Cui, Mingyu
Yang, Dongchao
Chen, Xueyuan
Meng, Helen
contents With the rise of Speech Large Language Models (SpeechLLMs), two dominant approaches have emerged for speech processing: discrete tokens and continuous features. Each approach has demonstrated strong capabilities in audio-related processing tasks. However, the performance gap between these two paradigms has not been thoroughly explored. To address this gap, we present a fair comparison of self-supervised learning (SSL)-based discrete and continuous features under the same experimental settings. We evaluate their performance across six spoken language understanding-related tasks using both small and large-scale LLMs (Qwen1.5-0.5B and Llama3.1-8B). We further conduct in-depth analyses, including efficient comparison, SSL layer analysis, LLM layer analysis, and robustness comparison. Our findings reveal that continuous features generally outperform discrete tokens in various tasks. Each speech processing method exhibits distinct characteristics and patterns in how it learns and processes speech information. We hope our results will provide valuable insights to advance spoken language understanding in SpeechLLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2508_17863
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Speech Discrete Tokens or Continuous Features? A Comparative Analysis for Spoken Language Understanding in SpeechLLMs
Wang, Dingdong
Li, Junan
Cui, Mingyu
Yang, Dongchao
Chen, Xueyuan
Meng, Helen
Computation and Language
Sound
With the rise of Speech Large Language Models (SpeechLLMs), two dominant approaches have emerged for speech processing: discrete tokens and continuous features. Each approach has demonstrated strong capabilities in audio-related processing tasks. However, the performance gap between these two paradigms has not been thoroughly explored. To address this gap, we present a fair comparison of self-supervised learning (SSL)-based discrete and continuous features under the same experimental settings. We evaluate their performance across six spoken language understanding-related tasks using both small and large-scale LLMs (Qwen1.5-0.5B and Llama3.1-8B). We further conduct in-depth analyses, including efficient comparison, SSL layer analysis, LLM layer analysis, and robustness comparison. Our findings reveal that continuous features generally outperform discrete tokens in various tasks. Each speech processing method exhibits distinct characteristics and patterns in how it learns and processes speech information. We hope our results will provide valuable insights to advance spoken language understanding in SpeechLLMs.
title Speech Discrete Tokens or Continuous Features? A Comparative Analysis for Spoken Language Understanding in SpeechLLMs
topic Computation and Language
Sound
url https://arxiv.org/abs/2508.17863