The unique characteristic sounds produced by urine as it impacts the surface of the water in a toilet are used to monitor men's urinary flow pattern and its dynamics. By detecting the intensity at selected acoustic frequencies, it is possible to accurately and precisely measure the urine flow rate. Techniques for analyzing urine flow and its dynamics employ sound levels that are detected at two or more distinct frequency regions or channels of the sound spectrum. One frequency region that is designated the measurement channel is where the sound measurement intensity strongly depends on urine flow levels. Another frequency region that is designated the reference channel is where the sound measurement intensity is not dependent on urine flow levels. By using a combination of measurements from the measurement channel and the reference channel, the urine-flow monitoring apparatus compensates for variations in operating conditions and other factors during use.