Towards Effective and Efficient Non-autoregressive decoders for Conformer and LLM-based ASR using Block-based Attention Mask

Fuente: arXiv
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Autori principali: Wang, Tianzi, Xie, Xurong, Jin, Zengrui, Geng, Mengzhe, Deng, Jiajun, Li, Zhaoqing, Hu, Shoukang, Hu, Shujie, Li, Guinan, Cui, Mingyu, Meng, Helen, Liu, Xunying
Natura: Preprint
Pubblicazione: 2025
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author Wang, Tianzi
Xie, Xurong
Jin, Zengrui
Geng, Mengzhe
Deng, Jiajun
Li, Zhaoqing
Hu, Shoukang
Hu, Shujie
Li, Guinan
Cui, Mingyu
Meng, Helen
Liu, Xunying
author_facet Wang, Tianzi
Xie, Xurong
Jin, Zengrui
Geng, Mengzhe
Deng, Jiajun
Li, Zhaoqing
Hu, Shoukang
Hu, Shujie
Li, Guinan
Cui, Mingyu
Meng, Helen
Liu, Xunying
contents Automatic speech recognition (ASR) systems often rely on autoregressive (AR) Transformer decoder architectures, which limit efficient inference parallelization due to their sequential nature. To this end, non-autoregressive (NAR) approaches aim primarily to achieve significant decoding speedup while the maintaining recognition accuracy that is comparable to AR baselines. This paper proposes a novel NAR block-based attention mask decoder (AMD) that effectively improves decoding efficiency while maintaining ASR accuracy, and also offering flexibility in balancing the performance-efficiency trade-off on both Conformer and large language model (LLM)-based ASR systems. The proposed AMD performs parallel inference within contiguous blocks of output labels while maintaining monotonic left-to-right prediction between blocks. A one-pass beam search algorithm is designed to dynamically fuse Connectionist Temporal Classification (CTC), AR decoder, and AMD probabilities. Experiments are conducted on normal speech LS960 and DBank elderly speech across: a) The Conformer encoder-decoder ASR system with filterbank input features; b) its integration with WavLM features; and c) further advancement by integrating an LLM-based decoder. On the LS960 task, the proposed AMD empowered tripartite decoder achieves decoding speedup ratios of up to 1.44x, 1.55x, and 2.31x under the three model configurations over the CTC + AR baselines, without statistically significant WER increases. When operating with real-time factors (RTFs) comparable to the baselines, the tripartite decoder produces statistically significant WER reductions of 0.19%, 0.62% and 0.13% absolute (4.3%, 16.3%, and 3.8% relative). Similar improvements are also obtained on the DBank task.
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id arxiv_https___arxiv_org_abs_2511_09084
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Towards Effective and Efficient Non-autoregressive decoders for Conformer and LLM-based ASR using Block-based Attention Mask
Wang, Tianzi
Xie, Xurong
Jin, Zengrui
Geng, Mengzhe
Deng, Jiajun
Li, Zhaoqing
Hu, Shoukang
Hu, Shujie
Li, Guinan
Cui, Mingyu
Meng, Helen
Liu, Xunying
Audio and Speech Processing
Automatic speech recognition (ASR) systems often rely on autoregressive (AR) Transformer decoder architectures, which limit efficient inference parallelization due to their sequential nature. To this end, non-autoregressive (NAR) approaches aim primarily to achieve significant decoding speedup while the maintaining recognition accuracy that is comparable to AR baselines. This paper proposes a novel NAR block-based attention mask decoder (AMD) that effectively improves decoding efficiency while maintaining ASR accuracy, and also offering flexibility in balancing the performance-efficiency trade-off on both Conformer and large language model (LLM)-based ASR systems. The proposed AMD performs parallel inference within contiguous blocks of output labels while maintaining monotonic left-to-right prediction between blocks. A one-pass beam search algorithm is designed to dynamically fuse Connectionist Temporal Classification (CTC), AR decoder, and AMD probabilities. Experiments are conducted on normal speech LS960 and DBank elderly speech across: a) The Conformer encoder-decoder ASR system with filterbank input features; b) its integration with WavLM features; and c) further advancement by integrating an LLM-based decoder. On the LS960 task, the proposed AMD empowered tripartite decoder achieves decoding speedup ratios of up to 1.44x, 1.55x, and 2.31x under the three model configurations over the CTC + AR baselines, without statistically significant WER increases. When operating with real-time factors (RTFs) comparable to the baselines, the tripartite decoder produces statistically significant WER reductions of 0.19%, 0.62% and 0.13% absolute (4.3%, 16.3%, and 3.8% relative). Similar improvements are also obtained on the DBank task.
title Towards Effective and Efficient Non-autoregressive decoders for Conformer and LLM-based ASR using Block-based Attention Mask
topic Audio and Speech Processing
url https://arxiv.org/abs/2511.09084