Towards Cross-Corpora Generalization for Low-Resource Spoken Language Identification

Low-resource spoken language identification (LID) systems are prone to poor generalization across unknown domains. In this study, using multiple widely used low-resourced South Asian LID corpora, we conduct an in-depth analysis for understanding the key non-lingual bias factors that create corpora mismatch and degrade LID generalization. To quantify the biases, we extract different data-driven and rule-based summary vectors that capture non-lingual aspects, such as speaker characteristics, spoken context, accents or dialects, recording channels, background noise, and environments. We then conduct a statistical analysis to identify the most crucial non-lingual bias factors and corpora mismatch components that impact LID performance. Following these analyses, we then propose effective bias compensation approaches for the most relevant summary vectors. We generate pseudo-labels using hierarchical clustering over language-domain-gender constrained summary vectors and use them to train adversarial networks with conditioned metric loss. The compensations learn invariance for the corpora mismatches due to the non-lingual biases and help to improve the generalization. With the proposed compensation method, we improve equal error rate up to 5.22% and 8.14% for the same-corpora and cross-corpora evaluations, respectively.