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. 2021 May 26;23(6):667. doi: 10.3390/e23060667

Table 1.

Deep learning-based methods for heart sounds classification.

S. No Reference Method Input Features Segment Optimizer Categories Performance on Test Dataset MAcc, Se, Sp, Acc
CNN-Based Methods
1 Maknickas et al., 2017
[25]
2D-CNN MFSC No RMSprop N, A 84.15, 80.63, 87.66, *
2 Tarik Alafif et al., 2020 [26] 2D-CNN + transfer learning MFCC NO SGD N, A *, *, *, 89.5%
3 Deng et al., 2020 [24] CNN + RNN Improved MFCC No Adam N, A 0.9834, 0.9866, 0.9801, *
4 Abduh et al., 2019 [27] 2D-DNN MFSC No * N, A 93.15, 89.30, 97.00, 95.50
5 Chen et al., 2018 [28] 2D-CNN Wavelet transform + Hilbert–Huang features No * N, M, EXT 93.25, 98, 88.5, 93
6 Rubin et al., 2016 [29] 2D-CNN MFCC Yes Adam N, A 83.99, 72.78, 95.21, *
7 Nilanon et al., 2016 [30] 2D-CNN Spectrograms No SGD N, A 81.11, 76.96, 85.27, *
8 Dominguez et al., 2018 [31] 2D-CNN Spectrograms No * N, A 94.16, 93.20, 95.12, 97.05
9 Bozkurt et al., 2018 [32] 2D-CNN MFCC + MFSC Yes * N, A 81.5, 84.5, 78.5, 81.5
10 Chen et al., 2019 [33] 2D-CNN MFSC No Adam N, A 94.81, 92.73, 96.90, *
11 Cheng et al., 2019 [34] 2D-CNN Spectrograms No * N, A 89.50, 91.00, 88.00, *
12 Fatih et al., 2019 [35] 2D-CNN Spectrograms No * N, M, EXT 0.80 (Accuracy on dataset A)
0.79 (Accuracy on dataset B)
13 Ryu et al., 2016 [36] 1D-CNN 1D time-series signals No SGD N, A 78.69, 66.63, 87.75, *
14 Xu et al., 2018 [37] 1D-CNN 1D time-series signals No SGD N, A 90.69, 86.21, 95.16, 93.28
15 Xiao et al., 2020 [38] 1D-CNN 1D time-series signals No SGD N, A 90.51, 85.29, 95.73, 93.56
16 Humayun et al., 2020
[39]
tConv-CNN (1D-CNN) 1D time-series signals Yes Adam N, A 81.49, 86.95, 76.02, *
17 Humayun et al., 2018
[40]
1D-CNN 1D time-series signals Yes SGD N, A 87.10, 90.91, 83.29, *
18 Li et al., 2019 [41] 1D-CNN Spectrograms No * N, A *, *, *, 96.48
19 Li et al., 2020 [42] 1D-CNN 497 features from time, amplitude, high-order statistics, cepstrum, frequency cyclostationary and entropy domains Yes Adam N, A *, 0.87, 0.721, 0.868
20 Xiao et al., 2020 [43] 1D-CNN 1D time-series signals No N, A *, 0.86, 0.95, 0.93
21 Shu Lih Oh et al., 2020
[44]
1D-CNN WaveNet 1D time-series signals NO Adam N, AS, MS, MR, MVP 0.953, 0.925, 0.981, 0.97
22 Baghel et al., 2020 [45] 1D-CNN 1D time-series signals No SGD N, AS, MS, MR, MVP *, *, *, 0.9860
RNN-Based Methods
23 Latif et al., 2018 [46] RNN (LSTM, BLSTM, GRU, BiGRU) MFCC Yes * N, A 98.33, 99.95, 96.71, 97.06 (LSTM)
98.61, 98.86, 98.36, 97.63 (BLSTM)
97.31, 96.69, 97.93, 95.42 (GRU)
97.87, 98.46, 97.28, 97.21 (BiGRU)
24 Khan et al., 2020 [47] LSTM MFCC No * N, A *, *, *, 91.39
25 Yang et al., 2016 [48] RNN 1D time-series signals No * N, A 80.18, 77.49, 82.87, *
26 Raza et al., 2018 [49] LSTM 1D time-series signals No Adam N, M, EXT *, *, *, 80.80
27 Westhuizen et al., 2017 [50] Bayesian LSTM LSTM 1D time-series signals No N, A 0.798, 0.707, 0.889, 0.798
0.7775, 0.675, 0.880, 0.778
Hybrid Methods
28 Wu et al., 2019 [51] Ensemble CNN pectrograms + MFSC + MFCC No * N, A 89.81, 91.73, 87.91, *
29 Noman et al., 2019 [52] Ensemble CNN (1D time-series signals + MFCC) Yes Scikit N, A 88.15, 89.94, 86.35, 89.22
30 Tschannen et al., 2016 [53] 2D-CNN+SVM Deep features Yes * N, A 81.22, 84.82, 77.62, *
31 Potes et al., 2016 [23] AdaBoost + 1D-CNN Time and frequency features, MFCC Yes * N, A 86.02, 94.24, 77.81, *
32 Gharehbaghi et al., 2019 [54] STGNN + MTGNN Time-series signal No * N, A *, 82.8, *, 84.2
33 Deperlioglu et al., 2020 [55] AEN 1D time-series signals No * N, M, EXT 0.9603 (Accuracy for normal), 0.9191 (Accuracy for extrasystole), 0.9011 (Accuracy for murmur)

* Abbreviations—N: normal heart sounds, M: murmur heart sounds, EXT: extrasystole heart sounds, AS: aortic stenosis, MS: mitral stenosis, MR: mitral regurgitation, MVP: mitral valve prolapse, MS: mitral stenosis, Acc: accuracy, MAcc: mean of specificity, Sp: specificity, Se: sensitivity.