Evaluation of Respiratory Sounds Using Image-Based Approaches for Health Measurement Applications

IEEE Open J Eng Med Biol. 2022 Sep 13:3:134-141. doi: 10.1109/OJEMB.2022.3202435. eCollection 2022.

Abstract

Goal: The evaluation of respiratory events using audio sensing in an at-home setting can be indicative of worsening health conditions. This paper investigates the use of image-based transfer learning applied to five audio visualizations to evaluate three classification tasks (C1: wet vs. dry vs. whooping cough vs. restricted breathing; C2: wet vs. dry cough; C3: cough vs. restricted breathing). Methods: The five visualizations (linear spectrogram, logarithmic spectrogram, Mel-spectrogram, wavelet scalograms, and aggregate images) are applied to a pre-trained AlexNet image classifier for all tasks. Results: The aggregate image-based classifier achieved the highest overall performance across all tasks with C1, C2, and C3 having testing accuracies of 0.88, 0.88, and 0.91 respectively. However, the Mel-spectrogram method had the highest testing accuracy (0.94) for C2. Conclusions: The classification of respiratory events using aggregate image inputs to transfer learning approaches may help healthcare professionals by providing information that would otherwise be unavailable to them.

Keywords: Acoustic signal processing; audio visualization; convolutional neural network; cough classification; respiratory classification.

Grants and funding

This work was supported in part by the National Research Council of Canada through Aging in Place Challenge Program, and in part by the Natural Sciences and Engineering Research Council of Canada through Discovery Grant Program and was completed in collaboration with the AGE-WELL SAM3 National Innovation Hub. The work of Frank Knoefel was supported by the University of Ottawa Brain and Mind – Bruyère Research Institute Chair in Primary Health Care Dementia Research.