Analyzing the Importance of Blank for CTC-Based Knowledge Distillation

Fuente: arXiv
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Autori principali: Hilmes, Benedikt, Rossenbach, Nick, Schlüter, Ralf
Natura: Preprint
Pubblicazione: 2025
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author Hilmes, Benedikt
Rossenbach, Nick
Schlüter, Ralf
author_facet Hilmes, Benedikt
Rossenbach, Nick
Schlüter, Ralf
contents With the rise of large pre-trained foundation models for automatic speech recognition new challenges appear. While the performance of these models is good, runtime and cost of inference increases. One approach to make use of their strength while retaining efficiency is to distill their knowledge to smaller models during training. In this work, we explore different CTC-based distillation variants, focusing on blank token handling. We show that common approaches like blank elimination do not always work off the shelf. We explore new blank selection patterns as a potential sweet spot between standard knowledge distillation and blank elimination mechanisms. Through the introduction of a symmetric selection method, we are able to remove the CTC loss during knowledge distillation with minimal to no performance degradation. With this, we make the training independent from target labels, potentially allowing for distillation on untranscribed audio data.
format Preprint
id arxiv_https___arxiv_org_abs_2506_01503
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Analyzing the Importance of Blank for CTC-Based Knowledge Distillation
Hilmes, Benedikt
Rossenbach, Nick
Schlüter, Ralf
Machine Learning
Sound
Audio and Speech Processing
With the rise of large pre-trained foundation models for automatic speech recognition new challenges appear. While the performance of these models is good, runtime and cost of inference increases. One approach to make use of their strength while retaining efficiency is to distill their knowledge to smaller models during training. In this work, we explore different CTC-based distillation variants, focusing on blank token handling. We show that common approaches like blank elimination do not always work off the shelf. We explore new blank selection patterns as a potential sweet spot between standard knowledge distillation and blank elimination mechanisms. Through the introduction of a symmetric selection method, we are able to remove the CTC loss during knowledge distillation with minimal to no performance degradation. With this, we make the training independent from target labels, potentially allowing for distillation on untranscribed audio data.
title Analyzing the Importance of Blank for CTC-Based Knowledge Distillation
topic Machine Learning
Sound
Audio and Speech Processing
url https://arxiv.org/abs/2506.01503