@inproceedings{liang-etal-2026-limits,
title = "The Limits of Data Scaling: Sub-token Utilization and Acoustic Saturation in Multilingual {ASR}",
author = "Liang, Siyu and
Ballier, Nicolas and
Levow, Gina-Anne and
Wright, Richard",
editor = "Piperidis, Stelios and
Bel, N{\'u}ria and
van den Heuvel, Henk and
Ide, Nancy and
Krek, Simon and
Toral, Antonio",
booktitle = "Proceedings of the Fifteenth Language Resources and Evaluation Conference",
month = may,
year = "2026",
address = "Palma de Mallorca, Spain",
publisher = "ELRA Language Resource Association",
url = "https://aclanthology.org/2026.lrec-1.457/",
doi = "10.63317/5pht8xx8yosb",
pages = "5785--5793",
abstract = "How much audio is needed to fully observe a multilingual ASR model{'}s learned sub-token inventory across languages, and does data disparity in multilingual pre-training affect how these tokens are utilized during inference? We address this question by analyzing Whisper{'}s decoding behavior during inference across 49 languages. By logging decoding candidate sub-tokens and tracking their cumulative discovery over time, we study the utilization pattern of the model{'}s sub-token space. Results show that the total number of discovered tokens remains largely independent of a language{'}s pre-training hours, indicating that data disparity does not strongly influence lexical diversity in the model{'}s hypothesis space. Sub-token discovery rates follow a consistent exponential saturation pattern across languages, suggesting a stable time window after which additional audio yields minimal new token activation. We refer to this convergence threshold as acoustic saturation time AST. Further analyses of rank{--}frequency distributions reveal Zipf-like patterns better modeled by a Zipf{--}Mandelbrot law, and mean sub-token length shows a positive correlation with resource level. Additionally, those metrics show more favorable patterns for languages in the Latin script than those in scripts such as Cyrillic, CJK and Semitic. Together, our study suggests that sub-token utilization during multilingual ASR inference is constrained more by the statistical, typological, and orthographical structure of the speech than by training data scale, providing an empirical basis for more equitable corpus construction and cross-lingual evaluation."
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<abstract>How much audio is needed to fully observe a multilingual ASR model’s learned sub-token inventory across languages, and does data disparity in multilingual pre-training affect how these tokens are utilized during inference? We address this question by analyzing Whisper’s decoding behavior during inference across 49 languages. By logging decoding candidate sub-tokens and tracking their cumulative discovery over time, we study the utilization pattern of the model’s sub-token space. Results show that the total number of discovered tokens remains largely independent of a language’s pre-training hours, indicating that data disparity does not strongly influence lexical diversity in the model’s hypothesis space. Sub-token discovery rates follow a consistent exponential saturation pattern across languages, suggesting a stable time window after which additional audio yields minimal new token activation. We refer to this convergence threshold as acoustic saturation time AST. Further analyses of rank–frequency distributions reveal Zipf-like patterns better modeled by a Zipf–Mandelbrot law, and mean sub-token length shows a positive correlation with resource level. Additionally, those metrics show more favorable patterns for languages in the Latin script than those in scripts such as Cyrillic, CJK and Semitic. Together, our study suggests that sub-token utilization during multilingual ASR inference is constrained more by the statistical, typological, and orthographical structure of the speech than by training data scale, providing an empirical basis for more equitable corpus construction and cross-lingual evaluation.</abstract>
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%0 Conference Proceedings
%T The Limits of Data Scaling: Sub-token Utilization and Acoustic Saturation in Multilingual ASR
%A Liang, Siyu
%A Ballier, Nicolas
%A Levow, Gina-Anne
%A Wright, Richard
%Y Piperidis, Stelios
%Y Bel, Núria
%Y van den Heuvel, Henk
%Y Ide, Nancy
%Y Krek, Simon
%Y Toral, Antonio
%S Proceedings of the Fifteenth Language Resources and Evaluation Conference
%D 2026
%8 May
%I ELRA Language Resource Association
%C Palma de Mallorca, Spain
%F liang-etal-2026-limits
%X How much audio is needed to fully observe a multilingual ASR model’s learned sub-token inventory across languages, and does data disparity in multilingual pre-training affect how these tokens are utilized during inference? We address this question by analyzing Whisper’s decoding behavior during inference across 49 languages. By logging decoding candidate sub-tokens and tracking their cumulative discovery over time, we study the utilization pattern of the model’s sub-token space. Results show that the total number of discovered tokens remains largely independent of a language’s pre-training hours, indicating that data disparity does not strongly influence lexical diversity in the model’s hypothesis space. Sub-token discovery rates follow a consistent exponential saturation pattern across languages, suggesting a stable time window after which additional audio yields minimal new token activation. We refer to this convergence threshold as acoustic saturation time AST. Further analyses of rank–frequency distributions reveal Zipf-like patterns better modeled by a Zipf–Mandelbrot law, and mean sub-token length shows a positive correlation with resource level. Additionally, those metrics show more favorable patterns for languages in the Latin script than those in scripts such as Cyrillic, CJK and Semitic. Together, our study suggests that sub-token utilization during multilingual ASR inference is constrained more by the statistical, typological, and orthographical structure of the speech than by training data scale, providing an empirical basis for more equitable corpus construction and cross-lingual evaluation.
%R 10.63317/5pht8xx8yosb
%U https://aclanthology.org/2026.lrec-1.457/
%U https://doi.org/10.63317/5pht8xx8yosb
%P 5785-5793
Markdown (Informal)
[The Limits of Data Scaling: Sub-token Utilization and Acoustic Saturation in Multilingual ASR](https://aclanthology.org/2026.lrec-1.457/) (Liang et al., LREC 2026)
ACL