Non-Invasive Measure of Stenosis Severity Through Spectral Analysis

This research~focused~on spectral analysis of the sound signal produced by valve stenosis. The physical system mimicked~the measurement of~a human pulse using a stethoscope. Contact microphones attached to the outside of a pipe collected sound signals produced~when the cross-sectional area of the pipe~was reduced~to 20{\%} and 30{\%} of the~initial~cross-sectional area. Water~was pumped~at a frequency of 1Hz and a flow~velocity~of 0.45m/s to~maintain~a Reynolds number that approximates blood flow of the heart, which is about 6400. Power spectra for the 20{\%} and 30{\%} restrictions showed an increase in the energy content of the sound signal across all frequencies. In addition to the overall increase, the 30{\%} restriction power spectrum was made up of 3 peaks centered around 33Hz, 43Hz and 100Hz while the 20{\%} restriction power spectrum had four distinct peaks centered around 20Hz,48Hz, 84Hz and 165Hz. This clear difference between the three power spectra indicates a positive relationship between stenosis severity and frequency produced, and forms the basis for further study of the relationship.