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Main Authors: Yanuka, Moran, Dixon, Paul, Finkelshtein, Eyal, Rotman, Daniel, Giryes, Raja
Format: Preprint
Published: 2025
Subjects:
Online Access:https://arxiv.org/abs/2511.13732
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author Yanuka, Moran
Dixon, Paul
Finkelshtein, Eyal
Rotman, Daniel
Giryes, Raja
author_facet Yanuka, Moran
Dixon, Paul
Finkelshtein, Eyal
Rotman, Daniel
Giryes, Raja
contents Speculative decoding accelerates autoregressive speech generation by letting a fast draft model propose tokens that a larger target model verifies. However, for speech LLMs that generate acoustic tokens, exact token matching is overly restrictive: many discrete tokens are acoustically or semantically interchangeable, reducing acceptance rates and limiting speedups. We introduce Principled Coarse-Graining (PCG), which verifies proposals at the level of Acoustic Similarity Groups (ASGs) derived from the target model's embedding space. By splitting each token's probability mass across the overlapping groups that contain it, we define an overlap-aware coarse-grained distribution and perform rejection sampling on the resulting group variable. This yields an exactness guarantee at the group level while allowing the accepted draft token to stand in for any member of the group in practice. On LibriTTS, PCG increases acceptance and throughput relative to standard speculative decoding and prior speech-specific relaxations while maintaining intelligibility and speaker similarity. These results suggest acoustically aware, group-level acceptance as a simple and general way to accelerate speech token generation while maintaining speech quality.
format Preprint
id arxiv_https___arxiv_org_abs_2511_13732
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Principled Coarse-Grained Acceptance for Speculative Decoding in Speech
Yanuka, Moran
Dixon, Paul
Finkelshtein, Eyal
Rotman, Daniel
Giryes, Raja
Audio and Speech Processing
Machine Learning
Speculative decoding accelerates autoregressive speech generation by letting a fast draft model propose tokens that a larger target model verifies. However, for speech LLMs that generate acoustic tokens, exact token matching is overly restrictive: many discrete tokens are acoustically or semantically interchangeable, reducing acceptance rates and limiting speedups. We introduce Principled Coarse-Graining (PCG), which verifies proposals at the level of Acoustic Similarity Groups (ASGs) derived from the target model's embedding space. By splitting each token's probability mass across the overlapping groups that contain it, we define an overlap-aware coarse-grained distribution and perform rejection sampling on the resulting group variable. This yields an exactness guarantee at the group level while allowing the accepted draft token to stand in for any member of the group in practice. On LibriTTS, PCG increases acceptance and throughput relative to standard speculative decoding and prior speech-specific relaxations while maintaining intelligibility and speaker similarity. These results suggest acoustically aware, group-level acceptance as a simple and general way to accelerate speech token generation while maintaining speech quality.
title Principled Coarse-Grained Acceptance for Speculative Decoding in Speech
topic Audio and Speech Processing
Machine Learning
url https://arxiv.org/abs/2511.13732