Urinary flow measurements via acoustic signatures with application to telemedicine

In this paper we investigate the potential of obtaining urinary flow measurements from acoustic signatures of of the urine stream produced by their impact on a liquid free surface. This hypothesis is driven by conceptually similar studies in the acoustics literature which have successfully correlated rainfall rates to sound emissions resulting from jet and droplet impacts on lakes and other large bodies of water. This approach, known as 'sonouroflowmetry' (SUF), if shown to be feasible and of sufficient accuracy could represent an attractive application for telemedicine. We report on acoustic measurements and correlation/trends obtained from controlled experimental simulations of male urination as well as limited clinical measurements. It is found that at physiological flow levels there is a general correlation between increasing flow rate and overall acoustic levels (dB). There is also a shift to lower characteristic/dominant frequencies corresponding to larger flow structures. The results, however, suggest that the interpretation in clouded by the interaction of the impacting jet with the toilet bottom surface at sufficient flow velocities and shallow toilet water levels. In general, the findings to date are supportive of this proof-of-concept, but numerous questions remains as to the eventual utility of this method as a practical measurement tool.