Development of an Electronic Stethoscope

An electronic stethoscope is designed and implemented for the diagnosis of some cardiac ailments. Graphs of the diagnosis are plotted using the electronic stethoscope, as well as results obtained for the purposes of inferences and analysis. With these inferences, the diagnosis of chest sounds can be easily carried out. With the results of this graph, early diagnoses can be realized, which can hinder cardiological ill health. With the electronic stethoscope, the auscultation of the chest becomes an effective and basic method for the diagnosis of some cardiological problems. An example of these cardiac issues is heart valve malfunction, which leads to heart murmurs. The electronic stethoscope can diagnose grade one and two heart murmurs and auscultation tachycardia patients, which leads to the detection of all kinds of chest sounds that the manual or conventional stethoscope may not be able to detect. In this work, the electret microphone capsule is connected to the microphone amplifier module (LM 386). The LM 386 has built-in automatic gain control (AGC), which is suitable for capturing a wide range of sound levels. The experimental analysis was conducted using multiple subjects to evaluate the system's accuracy, consistency, and noise-filtering capabilities. The device was tested on four subjects. The results are summarized as follows: a normal heart rate of 72 beats and normal heart sounds with a high signal clarity for subject one, and a heart rate of 85 and high noise interference with low signal clarity for subject four. Ten subjects were tested for the Phonocardiogram (PCG), which includes S1, S2, and murmurs. The parameters visualized in the system and plotted in the graph are time ((0.2s, 15db) and (0.5s, -12db)) (in seconds), amplitude (15db, high; -12db, low) (sound intensity in decibels), frequency ((125Hz, 15db) and (100, -12db)) (in hertz), and heart rate variability (HRV) ((68, 0.5s) and (80, 0.5s)).