The Connecticut River Estuary is highly stratified, strongly influenced by fresh water discharge and tides, and characterized by hydrographic features such as dynamic fronts, plumes, internal waves, shear instability, and the incoming salt-wedge. An experiment was conducted to measure the impact of these hydrographic features on the propagation of high-frequency sound, and to use the path-averaged acoustic fields to infer properties of salinity microstructure. Two 120 kHz, 4-element arrays, each element with reciprocal transmission capabilities, were deployed for 5 days mid-water-column, spanning multiple tidal cycles and a range of discharge conditions. Extensive environmental data were collected, including ADCP profiles, CTD profiles, salinity microstructure at various depths, and broadband acoustic backscatter (100-600 kHz). Results from this experiment show that 1) shear instabilities dominated the structure of the sound propagation during the ebb tide and were coherent features across the propagation...