Testing sensors for body surface vibration measurements

A system was constructed to test the performance of transducers for the detection of body surface vibrations. A phantom was manufactured of a gel that approximates properties of soft tissue and the different sensors were used to measure the vibrations at the model surface. One speaker was buried in the phantom to introduce a simulated signal, and another introduced simulated ambient room noise. The frequency-dependent sensor sensitivity to the input signal and ambient noise was investigated for six different sensor types. The laser Doppler sensor provided non-contact measurement with no surface loading, and was chosen as the reference sensor. The sensitivity of all sensors to ambient noise was satisfactory with the all-coupled sensor being most sensitive. The electronic stethoscope had the advantages of high sensitivity to the desired signal, low sensitivity to ambient noise and low cost