The Duration of Normal Heart Sounds

Signal Processing and Extensive Characterization Method of Heart Sounds Based on Wavelet Analysis

“…8). The result of Table I for the normal subject was similar to Luisada et al [8]. Their experimental results that the average t dur of S 1 was 0.146 s (at the apex) and 0.140 s (at the aortic area) of the subjects with the age above 10 years old, also the average t dur of S 2 in the same conditions was 0.097 s and 0.104 s, respectively.…”

“…The S 1 sound is produced of compound in nature by three stages [8], [9]: firstly, low-frequency beginning, due to myocardial tension. Secondly, higher-frequency central stage, due to valvular events; the central stage contains at least four vibrations that correlate with the motion of the four valves in the following order: mitral (M 1 ) closing, tricuspid (T 1 ) closing, pulmonic (P 2 ) opening, and aortic (A 2 ) opening.…”

“…The S 2 sound is generated of three stages as well as the S 1 sound [8], [9]: firstly, low-frequency beginning, due to eddies preceding the valvular closure. Secondly, central stage of higher-frequency, due to closing of the semilunar valves (A 2 and P 2 ).…”

On Cardiovascular Sound

“…At least partial explanation is provided for the frequent failure of conventional phonocardiography to demonstrate the typical diamond-shape of "ejection stenosis" murmurs, the crescendo character of the presystolic murmur of mitral stenosis or the decrescendo of aortic regurgitation: the contribution of the higher frequencies is not recorded because of lack of sensitivity in that range. 5. Since artefacts such as borborygmi, breath sounds, hiccoughs, electrical interference, speech sound can be identified in the spectral phonocardiogram, they are less likely to occasion confusion.…”

Non Invasive Foetal Monitoring with a Combined ECG - PCG System

“…The proposed algorithms provide all the required information; the occurrence of PEP can be estimated by means of the QRS wave detection while the timing of the other events can be estimated by the detection of S1 and S2. In both S1 and S2, the main part of the complex consists of large vibrations, due to the movements of the valves (Luisada et al, 1949). Therefore, division of each S1 and S2 into different phases which correspond to different valvular events (mitral valve closure and opening and aortic valve closure) is relatively easy (Fleming et al, 1986).…”