Effect of Contact Force on Foetal Heart Sound Recordings

Foetal heart rate is an important parameter of the foetal well-being. Foetal phonocardiography is one of the noninvasive methods to detect the foetal heart rate by recording the foetal sounds. This is an alternative for the methods like foetal electrocardiography and foetal doppler. The aim of this paper is to compare the performance of the three sensors - two digital stethoscopes and a contact microphone, for foetal heart sound acquisition. The performance is compared based on the SNR of the data acquired by the sensors. It was found that contact force of the sensor affects the quality of the acquired data and there exists an optimum contact force for the sensors (3N for contact microphone and ~0.5N for stethoscope) at which the SNR of the signal is the highest.