Semi-Supervised NMF-CNN for Sound Event Detection

In this paper, a combinative approach using Nonnegative Matrix Factorization (NMF) and Convolutional Neural Network (CNN) is proposed for audio clip Sound Event Detection (SED). The main idea begins with the use of NMF to approximate strong labels for the weakly labeled data. Subsequently, using the approximated strongly labeled data, two different CNNs are trained in a semi-supervised framework where one CNN is used for clip-level prediction and the other for frame-level prediction. Based on this idea, our model can achieve an event-based F1-score of 45.7% on the Detection and Classification of Acoustic Scenes and Events (DCASE) 2020 Challenge Task 4 validation dataset. By ensembling models through averaging the posterior outputs, event-based F1-score can be increased to 48.6%. By comparing with the baseline model, our proposed models outperform the baseline model by over 8%. By testing our models on the DCASE 2020 Challenge Task 4 test set, our models can achieve an event-based F1-score of 44.4% while our ensembled system can achieve an event-based F1-score of 46.3%. Such results have a minimum margin of 7% over the baseline system which demonstrates the robustness of our proposed method on different datasets.