arXiv AI

Whispering Wisely: Smart Subset Selection for ASR Fine-Tuning

The paper proposes an embedding‑based subset selection method for fine‑tuning Automatic Speech Recognition models, specifically using Whisper’s pretrained encoder to map audio samples into a fixed‑dimensional space and applying a greedy k‑center algorithm to pick diverse, representative subsets. Experiments on Hebrew and Danish show that k‑center selection outperforms random sampling, especially when the training set is small, and that the chosen subsets exhibit greater lexical diversity. The results suggest that this practical strategy can improve ASR performance under limited data budgets.

arXiv Computation and Language
Oct 23

Group Relative Policy Optimisation Improves Multilingual Speech Recognition in Low-Resource Languages

Group Relative Policy Optimisation (GRPO) is applied to a non‑LLM encoder‑decoder ASR model, Whisper‑large‑v3, to improve multilingual speech recognition across 51 African languages. The method mitigates exposure bias from teacher forcing, especially benefiting low‑resource and noisy audio scenarios. The resulting model, SunflowerASR, sets new macro‑averaged WER records on AfriVox‑v2 (0.227) and SimbaBench (0.372).

By Tim Wenjie Hu, Evelyn Nafula Ouma, Benjamin Akera, John A. Quinn
arXiv AI
Aug 20

Understanding Multilingual Medical ASR Adaptation Through Layer-Wise Analysis

The paper examines how multilingual medical adaptation affects the internal representations of Whisper ASR models. By comparing various fine‑tuning strategies—zero‑shot decoding, English‑only, German‑only, two‑stage EN→EN+DE, and direct EN+DE fine‑tuning—it shows that fine‑tuning significantly improves performance, with the best model varying by setting. Layer‑wise encoder analysis reveals that English medical fine‑tuning drives the main representation shift, while multilingual continuation largely preserves the adapted space, and that domain and language signals remain recoverable across layers.

By Souranil Kahali, Rituparna Bose, Abner Hernandez, Tomas Arias-Vergara, Andreas Maier, Ning Ma, Paula Andrea Perez-Toro
arXiv Computation and Language
Sep 18

Phoneme-guided TTS augmentation for ASR: A unified pipeline and multilingual evaluation

The paper introduces a phoneme-guided text-to-speech (TTS) augmentation pipeline for automatic speech recognition (ASR) that links multilingual speech generation with candidate-text selection and reference-speech quality control. It proposes phoneme-frequency-guided selection (PFGS), which prioritizes candidate texts containing common phonetic content based on real ASR training transcripts. Experiments across four languages and 13 test sets show that random text selection improves recognition on 11 test sets, while PFGS further improves nine test sets with relative word error rate reductions up to 19.3%, and reference-speech filtering also contributes to performance gains.

By Zhen Wang, TianRui Wu, RongQi Han, Hao Wu, Wei Liang, Wei Xu
arXiv Computation and Language
Aug 27

Generative vs. Encoder Large Language Models for ASR Evaluation: A Comparative Study

The paper compares encoder‑based and generative decoder‑based large language models for evaluating automatic speech recognition (ASR). It examines BERTScore and SemDist across various LLMs, layers, and pooling strategies, finding that both metrics can strongly correlate with human judgments when properly configured. For generative LLMs, the study explores pairwise hypothesis selection via prompting and direct error classification, showing that while encoder‑based metrics remain competitive, generative models excel in hypothesis comparison and enhance interpretability of ASR evaluation.

By Thibault Ba\~neras-Roux, Shashi Kumar, Driss Khalil, Sergio Burdisso, Petr Motlicek, Shiran Liu, Mickael Rouvier, Jane Wottawa, Richard Dufour