Title: Finding a Generalizable Method for Source-Free Domain Adaptation in AI
Deep learning has made great strides in solving various problems, but there are still challenges when deploying models in unseen domains. Source-free domain adaptation (SFDA) aims to adapt pre-trained models to new domains using only unlabeled data. This is crucial as training large-scale models is computationally expensive and harmful to the environment. Transfer learning and SFDA are areas of research that can leverage existing models and address real-world applications where labeled examples are unavailable.
The Importance of SFDA in Bioacoustics:
SFDA research has primarily focused on simple distribution shifts in image classification tasks. However, in the field of bioacoustics, distribution shifts are common and present challenges for practitioners. By studying SFDA in bioacoustics, we can understand the generalizability of existing methods, identify research gaps, and aid biodiversity preservation efforts.
Distribution Shifts in Bioacoustics:
Bioacoustics, which involves the study of sounds produced by living organisms, experiences natural distribution shifts. In the bioacoustics field, practitioners aim to analyze passive recordings called “soundscapes” obtained through omnidirectional microphones instead of focalized recordings. Soundscapes are more challenging due to lower signal-to-noise ratios, multiple vocalizing birds, and environmental noise. Moreover, different soundscapes come from different locations, resulting in extreme label shifts. This introduces a multi-label classification problem, unlike the single-label image classification typically studied in SFDA.
Benchmarking SFDA Models in Bioacoustics:
Six state-of-the-art SFDA methods were benchmarked in bioacoustics, and surprisingly, none consistently outperformed the source model on all target domains. Existing methods like Tent, SHOT, and AdaBN struggled to handle the distribution shifts and multi-label scenario. For instance, Tent collapsed when faced with the complexity of bioacoustics tasks.
Introducing NOTELA for Improved Adaptation:
However, there is a promising approach called Noisy Student, which encourages the model to reconstruct its own predictions using random noise. In bioacoustics, we propose a variant called Dropout Student (DS) that limits the influence of individual neurons or filters during predictions. Although DS faces model collapse issues, we believe this occurs because the source model lacks confidence in the target domains. To address this, we introduce NOisy student TEacher with Laplacian Adjustment (NOTELA), which utilizes the feature space directly to refine the adaptation process.
Evaluating SFDA methods solely on common datasets limits our understanding of their performance and generalizability. To fulfill their promise, SFDA methods should be tested on a wider range of distribution shifts, including naturally-occurring shifts in high-impact applications like bioacoustics. By studying SFDA in bioacoustics, we can bridge the gap between existing methods and real-world challenges, benefiting both researchers and practitioners in the field, and contributing to biodiversity preservation efforts.