Language Modeling for Code-Switching: Evaluation, Integration of Monolingual Data, and Discriminative Training
This addresses the problem of limited data and evaluation for code-switched language modeling in ASR, though it is incremental in improving existing methods.
The paper tackles language modeling for code-switched English-Spanish in ASR by proposing an evaluation setup decoupled from ASR systems and demonstrating that discriminative training outperforms generative modeling, with effective training using large monolingual data and fine-tuning on small code-switched data.
We focus on the problem of language modeling for code-switched language, in the context of automatic speech recognition (ASR). Language modeling for code-switched language is challenging for (at least) three reasons: (1) lack of available large-scale code-switched data for training; (2) lack of a replicable evaluation setup that is ASR directed yet isolates language modeling performance from the other intricacies of the ASR system; and (3) the reliance on generative modeling. We tackle these three issues: we propose an ASR-motivated evaluation setup which is decoupled from an ASR system and the choice of vocabulary, and provide an evaluation dataset for English-Spanish code-switching. This setup lends itself to a discriminative training approach, which we demonstrate to work better than generative language modeling. Finally, we explore a variety of training protocols and verify the effectiveness of training with large amounts of monolingual data followed by fine-tuning with small amounts of code-switched data, for both the generative and discriminative cases.