Generalized blind delayed source separation model for online non-invasive twin-fetal sound separation: a phantom study.

The fetal phonocardiogram, which is the acoustic recording of mechanical activity of the fetal heart, facilitates the measurement of the instantaneous fetal heart rate, beat-to-beat differences and duration of systolic and diastolic phases. These measures are sensitive indicators of cardiac function, reflecting fetal well-being. This paper provides an algorithm to non-invasively estimate the phonocardiogram of an individual fetus in a multiple fetus pregnancy. A mixture of fetal phonocardiograms is modeled by a generalized pure delayed mixing model. Mutual independence of fetal phonocardiograms is assumed to apply blind source separation based techniques to extract the fetal phonocardiograms from their mixtures. The performance of the algorithm is verified through simulation results and on experimental data obtained from a phantom that is used to simulate a twin pregnancy.