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Main Authors: Zhang, Xin, Li, Lin, Lu, Xiangni, Liu, Jianquan, Lee, Kong Aik
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2510.20504
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author Zhang, Xin
Li, Lin
Lu, Xiangni
Liu, Jianquan
Lee, Kong Aik
author_facet Zhang, Xin
Li, Lin
Lu, Xiangni
Liu, Jianquan
Lee, Kong Aik
contents Speech codecs serve as bridges between continuous speech signals and large language models, yet face an inherent conflict between acoustic fidelity and semantic preservation. To mitigate this conflict, prevailing methods augment acoustic codecs with complex semantic supervision. We explore the opposite direction: a semantic-first approach that starts from a semantically-capable model and adapts it for high-fidelity acoustic reconstruction. Through empirical analysis, we discover that targeted architectural simplification can unlock the acoustic modeling potential of Whisper, a text-aligned Automatic Speech Recognition (ASR) model. Based on this finding, we propose SimWhisper-Codec, a novel codec that balances the semantic and acoustic preservation by leveraging a frozen, simplified Whisper encoder without requiring external supervision. Experimental results demonstrate that SimWhisper-Codec achieves superior performance in both semantic preservation and acoustic quality compared to semantically-supervised codecs such as Mimi Codec and SpeechTokenizer at similar bitrates, validating the effectiveness of our semantic-first approach. Code is available at https://github.com/ZhangXinWhut/SimWhisper-Codec.
format Preprint
id arxiv_https___arxiv_org_abs_2510_20504
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Speaking Clearly: A Simplified Whisper-Based Codec for Low-Bitrate Speech Coding
Zhang, Xin
Li, Lin
Lu, Xiangni
Liu, Jianquan
Lee, Kong Aik
Sound
Speech codecs serve as bridges between continuous speech signals and large language models, yet face an inherent conflict between acoustic fidelity and semantic preservation. To mitigate this conflict, prevailing methods augment acoustic codecs with complex semantic supervision. We explore the opposite direction: a semantic-first approach that starts from a semantically-capable model and adapts it for high-fidelity acoustic reconstruction. Through empirical analysis, we discover that targeted architectural simplification can unlock the acoustic modeling potential of Whisper, a text-aligned Automatic Speech Recognition (ASR) model. Based on this finding, we propose SimWhisper-Codec, a novel codec that balances the semantic and acoustic preservation by leveraging a frozen, simplified Whisper encoder without requiring external supervision. Experimental results demonstrate that SimWhisper-Codec achieves superior performance in both semantic preservation and acoustic quality compared to semantically-supervised codecs such as Mimi Codec and SpeechTokenizer at similar bitrates, validating the effectiveness of our semantic-first approach. Code is available at https://github.com/ZhangXinWhut/SimWhisper-Codec.
title Speaking Clearly: A Simplified Whisper-Based Codec for Low-Bitrate Speech Coding
topic Sound
url https://arxiv.org/abs/2510.20504