Whisfusion: Parallel ASR Decoding via a Diffusion Transformer

Fuente: arXiv
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Autores principales: Kwon, Taeyoun, Ahn, Junhyuk, Yun, Taegeun, Jwa, Heeju, Choi, Yoonchae, Park, Siwon, Kim, Nam-Joon, Kim, Jangchan, Ryu, Hyun Gon, Lee, Hyuk-Jae
Formato: Preprint
Publicado: 2025
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author Kwon, Taeyoun
Ahn, Junhyuk
Yun, Taegeun
Jwa, Heeju
Choi, Yoonchae
Park, Siwon
Kim, Nam-Joon
Kim, Jangchan
Ryu, Hyun Gon
Lee, Hyuk-Jae
author_facet Kwon, Taeyoun
Ahn, Junhyuk
Yun, Taegeun
Jwa, Heeju
Choi, Yoonchae
Park, Siwon
Kim, Nam-Joon
Kim, Jangchan
Ryu, Hyun Gon
Lee, Hyuk-Jae
contents Fast Automatic Speech Recognition (ASR) is critical for latency-sensitive applications such as real-time captioning and meeting transcription. However, truly parallel ASR decoding remains challenging due to the sequential nature of autoregressive (AR) decoders and the context limitations of non-autoregressive (NAR) methods. While modern ASR encoders can process up to 30 seconds of audio at once, AR decoders still generate tokens sequentially, creating a latency bottleneck. We propose Whisfusion, the first framework to fuse a pre-trained Whisper encoder with a text diffusion decoder. This NAR architecture resolves the AR latency bottleneck by processing the entire acoustic context in parallel at every decoding step. A lightweight cross-attention adapter trained via parameter-efficient fine-tuning (PEFT) bridges the two modalities. We also introduce a batch-parallel, multi-step decoding strategy that improves accuracy by increasing the number of candidates with minimal impact on speed. Fine-tuned solely on LibriSpeech (960h), Whisfusion achieves a lower WER than Whisper-tiny (8.3% vs. 9.7%), and offers comparable latency on short audio. For longer utterances (>20s), it is up to 2.6x faster than the AR baseline, establishing a new, efficient operating point for long-form ASR. The implementation and training scripts are available at https://github.com/taeyoun811/Whisfusion.
format Preprint
id arxiv_https___arxiv_org_abs_2508_07048
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Whisfusion: Parallel ASR Decoding via a Diffusion Transformer
Kwon, Taeyoun
Ahn, Junhyuk
Yun, Taegeun
Jwa, Heeju
Choi, Yoonchae
Park, Siwon
Kim, Nam-Joon
Kim, Jangchan
Ryu, Hyun Gon
Lee, Hyuk-Jae
Sound
Artificial Intelligence
Machine Learning
Audio and Speech Processing
Fast Automatic Speech Recognition (ASR) is critical for latency-sensitive applications such as real-time captioning and meeting transcription. However, truly parallel ASR decoding remains challenging due to the sequential nature of autoregressive (AR) decoders and the context limitations of non-autoregressive (NAR) methods. While modern ASR encoders can process up to 30 seconds of audio at once, AR decoders still generate tokens sequentially, creating a latency bottleneck. We propose Whisfusion, the first framework to fuse a pre-trained Whisper encoder with a text diffusion decoder. This NAR architecture resolves the AR latency bottleneck by processing the entire acoustic context in parallel at every decoding step. A lightweight cross-attention adapter trained via parameter-efficient fine-tuning (PEFT) bridges the two modalities. We also introduce a batch-parallel, multi-step decoding strategy that improves accuracy by increasing the number of candidates with minimal impact on speed. Fine-tuned solely on LibriSpeech (960h), Whisfusion achieves a lower WER than Whisper-tiny (8.3% vs. 9.7%), and offers comparable latency on short audio. For longer utterances (>20s), it is up to 2.6x faster than the AR baseline, establishing a new, efficient operating point for long-form ASR. The implementation and training scripts are available at https://github.com/taeyoun811/Whisfusion.
title Whisfusion: Parallel ASR Decoding via a Diffusion Transformer
topic Sound
Artificial Intelligence
Machine Learning
Audio and Speech Processing
url https://arxiv.org/abs/2508.07048