Figure 3

Flow diagram illustrating the training of the acoustic models.
The second heart sounds were extracted from the recordings as shown in Fig. 1. The process described in Fig. 2 obtained the Mel-Frequency Cepstral Coefficients (MFCC) feature vectors. The MFCC feature vectors for the subjects with PH (mean PA pressure ≥25 mmHg) were combined into one matrix, and the feature vectors for the subjects with normal PA pressures (mean PA pressure <25 mmHg) were combined into another matrix. A Gaussian Mixture Model (GMM) is fitted to the feature vector matrices, resulting in one model for all subjects with PH and one for all subjects without PH.