Fig 9. Bi-directional long short-term memory (BiLSTM) network activations extracted for five examples from COVID-19 and healthy subjects using shallow breathing recordings.

The activations were extracted from the last layer (applied on the flattened convolutional neural network (CNN) features vector) of the deep learning network (BiLSTM) for five examples from COVID-19 (a-f) and healthy (g-l) subjects.