Task Arithmetic with Support Languages for Low-Resource ASR
Emma Rafkin, Dan DeGenaro, Xiulin Yang
TL;DR
This paper tackles low-resource ASR by leveraging genetically related high-resource languages through task arithmetic on Whisper-based systems, using task vectors and LoRA adapters to merge target-language models with related support-language models. It defines a formal merging operation $tau_S = theta_S - theta$ and $theta_final = theta_T + lambda tau_S$ (and analogous LoRA merging) and optimizes the scaling parameter $lambda$ on target validation data to improve WER. Evaluating on 21 target languages and five unseen ones in the Mozilla CV spontaneous-speech task, the approach yields consistent WER reductions, with smaller Whisper-tiny models often outperforming larger variants and higher gains when support languages are closely related. The study highlights the importance of language similarity, proxy languages, and model selection for effective cross-language transfer in low-resource ASR, pointing to more efficient and data-conscious ASR for underrepresented languages.
Abstract
The development of resource-constrained approaches to automatic speech recognition (ASR) is of great interest due to its broad applicability to many low-resource languages for which there is scant usable data. Existing approaches to many low-resource natural language processing tasks leverage additional data from higher-resource languages that are closely related to a target low-resource language. One increasingly popular approach uses task arithmetic to combine models trained on different tasks to create a model for a task where there is little to no training data. In this paper, we consider training on a particular language to be a task, and we generate task vectors by fine-tuning variants of the Whisper ASR system. For pairings of high- and low-resource languages, we merge task vectors via a linear combination, optimizing the weights of the linear combination on the downstream word error rate on the low-resource target language's validation set. We find that this approach consistently improves performance on the target languages.
