Towards Domain Invariant Heart Sound Abnormality Detection using Learnable Filterbanks

TL;DR

This paper introduces a learnable filterbank CNN architecture that enhances robustness in heart sound abnormality detection across different domains, improving accuracy and reliability of automated cardiac screening systems.

Contribution

It proposes a novel CNN layer with time-convolutional units that emulate FIR filters, enabling adaptive feature extraction for domain-invariant heart sound analysis.

Findings

Outperforms existing methods on multi-domain datasets

Achieves up to 11.84% relative improvement in MAcc

Demonstrates robustness to sensor and domain variability

Abstract

Cardiac auscultation is the most practiced non-invasive and cost-effective procedure for the early diagnosis of heart diseases. While machine learning based systems can aid in automatically screening patients, the robustness of these systems is affected by numerous factors including the stethoscope/sensor, environment, and data collection protocol. This paper studies the adverse effect of domain variability on heart sound abnormality detection and develops strategies to address this problem. Methods: We propose a novel Convolutional Neural Network (CNN) layer, consisting of time-convolutional (tConv) units, that emulate Finite Impulse Response (FIR) filters. The filter coefficients can be updated via backpropagation and be stacked in the front-end of the network as a learnable filterbank. Results: On publicly available multi-domain datasets, the proposed method surpasses the top-scoring systems found in the literature for heart sound abnormality detection (a binary classification task). We utilized sensitivity, specificity, F-1 score and Macc (average of sensitivity and specificity) as performance metrics. Our systems achieved relative improvements of up to 11.84% in terms of MAcc, compared to state-of-the-art methods. Conclusion: The results demonstrate the effectiveness of the proposed learnable filterbank CNN architecture in achieving robustness towards sensor/domain variability in PCG signals. Significance: The proposed methods pave the way for deploying automated cardiac screening systems in diversified and underserved communities.