  Lifelong audio feature extraction involves learning new sound classes
incrementally, which is essential for adapting to new data distributions over
time. However, optimizing the model only on new data can lead to catastrophic
forgetting of previously learned tasks, which undermines the model's ability to
perform well over the long term. This paper introduces a new approach to
continual audio representation learning called DeCoR. Unlike other methods that
store previous data, features, or models, DeCoR indirectly distills knowledge
from an earlier model to the latest by predicting quantization indices from a
delayed codebook. We demonstrate that DeCoR improves acoustic scene
classification accuracy and integrates well with continual self-supervised
representation learning. Our approach introduces minimal storage and
computation overhead, making it a lightweight and efficient solution for
continual learning.
