Do we really need a segmentation step in heart sound classification algorithms?
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Updated: Oct 10, 2025

Semi-automated Optical Heartbeat Analysis of Small Hearts
Published on: September 16, 2009
Insights
Heart sound segmentation is crucial for cardiovascular disease detection. Advanced models like GRU and CNN can identify heart murmurs without segmentation, while SVM and RF require it for optimal performance.
Area of Science:
- Cardiology
- Biomedical Signal Processing
- Machine Learning in Healthcare
Background:
- Cardiac auscultation is a primary method for detecting cardiovascular diseases (CVDs).
- Automated CVD detection relies on analyzing heart sounds, with segmentation (heart sound boundary detection) being a critical step.
- The necessity of a dedicated heartbeat alignment step within the signal classification pipeline is currently debated.
Purpose of the Study:
- To evaluate the impact of a heartbeat alignment step on the performance of various machine learning algorithms for cardiovascular disease detection.
- To determine if advanced algorithms can effectively detect heart murmurs without explicit segmentation.
Main Methods:
- Comparison of machine learning algorithms, including deep learning models (Gate Recurrent Unit Network, Convolutional Neural Network) and traditional methods (Support Vector Machine, Random Forest).
- Evaluation of algorithm performance with and without a preceding heartbeat alignment/segmentation step.
- Assessment of the ability to detect heart murmurs and heart sounds.
Main Results:
- Gate Recurrent Unit (GRU) Network and Convolutional Neural Network (CNN) demonstrated robustness, accurately detecting heart murmurs even without a heartbeat alignment step.
- Support Vector Machine (SVM) and Random Forest (RF) algorithms showed a performance decrease of approximately 5% when the explicit segmentation step was omitted.
- These findings indicate that advanced deep learning models may obviate the need for traditional segmentation in certain cardiac auscultation analysis tasks.
Conclusions:
- Deep learning models like GRU and CNN offer a more streamlined approach to heart sound analysis for CVD screening, potentially reducing computational steps.
- Traditional machine learning models (SVM, RF) still benefit significantly from precise heart sound segmentation for accurate murmur detection.
- The study highlights the evolving role of segmentation in automated cardiac auscultation, suggesting a shift towards segmentation-free analysis with advanced AI.
Abstract:
Cardiac auscultation is the key screening procedure to detect and identify cardiovascular diseases (CVDs). One of many steps to automatically detect CVDs using auscultation, concerns the detection and delimitation of the heart sound boundaries, a process known as segmentation. Whether to include or not a segmentation step in the signal classification pipeline is nowadays a topic of discussion. Up to our knowledge, the outcome of a segmentation algorithm has been used almost exclusively to align the different signal segments according to the heartbeat. In this paper, the need for a heartbeat alignment step is tested and evaluated over different machine learning algorithms, including deep learning solutions. From the different classifiers tested, Gate Recurrent Unit (GRU) Network and Convolutional Neural Network (CNN) algorithms are shown to be the most robust. Namely, these algorithms can detect the presence of heart murmurs even without a heartbeat alignment step. Furthermore, Support Vector Machine (SVM) and Random Forest (RF) algorithms require an explicit segmentation step to effectively detect heart sounds and murmurs, the overall performance is expected drop approximately 5% on both cases.
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