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Updated: Nov 8, 2025

Semi-automated Optical Heartbeat Analysis of Small Hearts
Published on: September 16, 2009
[Recognition of S1 and S2 heart sounds with two-stream convolutional neural networks]
Yujing Shen1, Xun Wang2, Min Tang1
1Center of Arrhythmia, Fuwai Hospital, Chinese Academy of Medical Sciences, Beijing 100037, P.R.China.
Insights
This study presents a novel method for classifying the first (S1) and second (S2) heart sounds using a two-stream convolutional neural network. The approach achieves high accuracy, aiding in precise heart sound segmentation for diagnosing cardiac conditions.
Area of Science:
- Cardiology
- Biomedical Engineering
- Artificial Intelligence in Medicine
Background:
- Auscultation of heart sounds is crucial for diagnosing cardiac conditions.
- Precise segmentation of heart sounds, specifically identifying the first (S1) and second (S2) heart sounds, is essential for accurate diagnosis.
- Existing methods may rely on cardiac cycle duration, which this study aims to bypass.
Purpose of the Study:
- To develop and evaluate a method for classifying S1 and S2 heart sounds based on their spectral properties.
- To improve the accuracy and efficiency of heart sound segmentation for clinical diagnosis.
- To avoid manual feature extraction in heart sound analysis.
Main Methods:
- Heart sounds (S1 and S2) were transformed into spectra using short-time Fourier transform.
- A two-stream convolutional neural network was employed for classification.
- The method focused on spectral properties, excluding cardiac cycle duration.
Main Results:
- The classification accuracy for S1 and S2 sounds reached 91.135% on the test dataset.
- Achieved a maximum sensitivity of 91.156% and specificity of 92.074%.
- The proposed method effectively avoids artificial feature extraction.
Conclusions:
- The developed method accurately distinguishes S1 and S2 heart sounds using spectral analysis and a convolutional neural network.
- This approach offers a computationally efficient and effective solution for real-time heart sound analysis.
- The findings support the potential for improved automated cardiac diagnosis through precise heart sound segmentation.
Abstract:
Auscultation of heart sounds is an important method for the diagnosis of heart conditions. For most people, the audible component of heart sound are the first heart sound (S1) and the second heart sound (S2). Different diseases usually generate murmurs at different stages in a cardiac cycle. Segmenting the heart sounds precisely is the prerequisite for diagnosis. S1 and S2 emerges at the beginning of systole and diastole, respectively. Locating S1 and S2 accurately is beneficial for the segmentation of heart sounds. This paper proposed a method to classify the S1 and S2 based on their properties, and did not take use of the duration of systole and diastole. S1 and S2 in the training dataset were transformed to spectra by short-time Fourier transform and be feed to the two-stream convolutional neural network. The classification accuracy of the test dataset was as high as 91.135%. The highest sensitivity and specificity were 91.156% and 92.074%, respectively. Extracting the features of the input signals artificially can be avoid with the method proposed in this article. The calculation is not complicated, which makes this method effective for distinguishing S1 and S2 in real time.
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