A sensing assemblage (1) for capturing a transit time, phase, or frequency of energy waves propagating through a medium is disclosed to measure a parameter of the muscular-skeletal system. The sensing assemblage (1) comprises a transducer (2) and a waveguide (3). The transducer (2) is coupled to the waveguide (3) at a first location. A second transducer (11) can be coupled to the waveguide (3) at a second location. An interface material that is transmissive to acoustic energy waves can be placed between transducers (402, 404) and a waveguide (414) to improve transfer. The interface material (408, 410) can affix the transducers (402, 404) to the waveguide (414). Alternatively, a reflecting feature (5) can be placed at a second location of the waveguide (3) to reflect acoustic waves back to the transducer (2) where transducer (2) emits energy waves into the medium and detects propagated energy waves.