TARQ: Tail-Aware Reconstruction Quantization for Rare-Word Robust Automatic Speech Recognition

Xinyu Wang, Ziyu Zhao, Ke Bai, Silin Meng, Dongming Shen, Xiao-Wen Chang, Yixuan He


Abstract
Data-aware post-training quantization (PTQ) minimizes a per-token reconstruction loss on a small calibration corpus—an objective natural for average-token preservation, but one that implicitly weights positions by their empirical frequency. For **Automatic Speech Recognition (ASR)**, this weighting is misaligned with tail-sensitive recognition risk: names, numerals, technical terms, and domain-specific words are practically important but receive proportionally little calibration mass.

We propose **Tail-Aware Reconstruction Quantization (TARQ)**, a label-free PTQ framework that shifts calibration toward the lexical tail. **TARQ** introduces **rareBAL**, a closed-form per-Linear-layer rule that equalizes the calibration mass contributed by common and tail positions, plus a metric-consistent residual correction that aligns the sequential PTQ sweep with the reweighted objective. **TARQ** requires no entity labels, no curated calibration set, no validation decoding, and no additional training.

Across eight ASR backbones and eight datasets under 4-bit weight-only quantization, **TARQ** improves mean rare-WER, the **Word Error Rate (WER)** restricted to rare-word reference positions, while maintaining competitive aggregate WER. It achieves the lowest cross-corpus rare-WER swing, **0.63 percentage points (pp)**, among compared methods, and transfers without modification to entity-rich evaluation on ProfASR and ContextASR-Speech-En with no entity supervision.
Anthology ID:
2026.findings-emnlp.664
Volume:
Findings of the Association for Computational Linguistics: EMNLP 2026
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
Findings
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
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Pages:
13928–13952
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URL:
https://aclanthology.org/2026.findings-emnlp.664/
DOI:
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Cite (ACL):
Xinyu Wang, Ziyu Zhao, Ke Bai, Silin Meng, Dongming Shen, Xiao-Wen Chang, and Yixuan He. 2026. TARQ: Tail-Aware Reconstruction Quantization for Rare-Word Robust Automatic Speech Recognition. In Findings of the Association for Computational Linguistics: EMNLP 2026, pages 13928–13952, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
TARQ: Tail-Aware Reconstruction Quantization for Rare-Word Robust Automatic Speech Recognition (Wang et al., Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-emnlp.664.pdf