Quality Adaptive Angular Margin Learning for Respiratory Sound Classification
This work addresses the challenge of limited feature generalizability in respiratory sound classification caused by variations in recording quality and class imbalance. To this end, the authors propose QLung, a novel framework that introduces, for the first time, a no-reference audio quality assessment metric based on spectral entropy and root-mean-square energy. This metric dynamically adjusts the angular margin in a normalized angular classifier and is combined with a log-scaling strategy to enhance intra-class compactness and inter-class separability, thereby stabilizing training. Evaluated on the ICBHI dataset, QLung achieves a 2.46% improvement over the cross-entropy baseline and demonstrates state-of-the-art out-of-distribution generalization performance on the SPRSound dataset.