Table 8.
Summary of the proposed features.
| Index | Domain | Num. of features | Motivation |
|---|---|---|---|
| 1 | Time interval | 20 | The time interval of each state has physiological meaning based on heart physiology. |
| 2 | Frequency spectrum of state | 308 | To reflect the frequency spectrum within state. |
| 3 | State amplitude | 12 | The amplitude is related to the heart hemodynamics. |
| 4 | Energy | 47 | To reflect energy distribution with respect to frequency band |
| 5 | Frequency spectrum of records | 27 | To reflect frequency spectrum within records |
| 6 | Cepstrum | 65 | To reflect the acoustic properties. |
| 7 | Cyclostationary | 4 | To reflect the degree of signal repetition. |
| 8 | High-order statistics | 16 | To reflect the skewness and kurtosis of each signal state. |
| 9 | Entropy | 16 | To reflect the PCG signal inherent complexity. |
| Total | - - | 515 | - - |