# Heart Murmur Quality Detection Using Deep Neural Networks with Attention Mechanism
## 3 Dataset  
The dataset used in this study is the publicly available set of the George B. Moody PhysioNet Challenge 2022, namely the CirCor DigiScope Phonocardiogram dataset [2; 30]. It was collected in northeast Brazil over the months of July-August 2014 and June-July 2015 [2] and contains 3163 PCG recordings from 942 patients at a sampling rate of 4000 Hz. The majority of patients have multiple PCG recordings, with most of them from the four auscultation locations: the aortic valve (AV), pulmonary valve (PV), tricuspid valve (TV), and mitral valve (MV), and a few are from other auscultation locations. As shown in Table 1, this dataset is balanced between males and females and was collected primarily from children and infants. The average lengths (\(\pm\)standard deviation) of the PCG recordings are 22.9 (\(\pm\)7.3) s with the shortest and longest lengths of 5.2 s and 64.5 s, respectively. The dataset provides segmentation labels (S1, systolic period, S2, and diastolic period) for each PCG recording and murmur locations for each patient. Significantly, it is labeled with many characteristics of murmurs including the most audible location, timing, shape, pitch, grading, and quality manually by a cardiac physiologist [30]. Specifically, the murmur grading is described as \"I/VI\", \"II/VI\", and \"III/VI\" based on Levine's scale [35]; the murmur pitch is described as \"High\", \"Medium\", and \"Low\"; the murmur timing is described as \"Early-\", \"Mid-\", and \"Late-\" systolic; and the murmur shape is described as \"Crescendo\", \"Decrescendo\", \"Diamond\", and \"Plateau\" [2]. The murmur quality is labeled as \"Blowing\", \"Harsh\", and \"Musical\", and all auscultation locations with murmurs in a single patient correspond to only one murmur quality. A \"Harsh\" murmur is described by a high-velocity blood flow from a higher to a lower pressure gradient, and a \"Blowing\" murmur is a sound caused by turbulent (rough) blood flow through the heart valves [2]. The murmur of aortic stenosis tends to be a harsh, grating murmur, whereas that of mitral regurgitation has a gentle, blowing quality [36]. However, the \"Musical\" quality is extremely rare, which may be related to some innocent murmurs [2]. Table 1 demonstrates that most murmurs are present in the systole period with very few in the diastolic period (2.8%); the majority of systolic murmur quality is determined as \"Blowing\" and \"Harsh\" with \"Musical\" murmurs being relatively rare (2.2%). Therefore, heart sounds with a systolic murmur quality described as \"Musical\" were excluded, and the study focused only on two types of heart sounds, i.e., systolic murmur quality described as \"Blowing\" and \"Harsh\". Also, not all heart sounds in all auscultation locations had murmurs for a patient diagnosed with murmurs, and the heart sounds in those auscultation locations where murmurs were present were studied only. After excluding the above, an analysis dataset of 174 patients with 604 recordings was included for analysis in the research. The details of the analysis dataset are displayed in Table 1. The average lengths (\(\pm\)standard deviation) of the PCG recordings in the analysis dataset are 22.2 (\(\pm\)7.9) s with the shortest and longest lengths of 6.4 s and 64.5 s, respectively. According to the segmentation labels, each recording was cut into segments that contain about seven cardiac cycles to have equivalent information of heart sounds. The segments have an average length (\(\pm\)standard deviation) of 4.1 (\(\pm\)0.7) s and no overlap between them. Some patients' PCGs could not be used due to the missing of their segmentation labels. The percentage of patients in murmur quality, timing, shape, grading, and pitch of analysis dataset after segmentation is given in Table 2. The number of segments for segments' murmur quality detection is 1266, with 747 labeled as \"Harsh\" and 519 labeled as \"Blowing\", while the number of patients for patients' murmur quality detection is 164 with 90 labeled as \"Harsh\" and 74 labeled as \"Blowing\".