Dave, UR - Understanding sound propagation

People are critical of sound effects in sci-fi films, because sound isn't propagated through a vacuum. After all, there is no atmosphere to conduct sound waves forward from their source. Many people take the transference of sound waves through our own atmosphere for granted, and even more people assume that sound travels through water the same way it travels through air. This is not only false, but sound actually gets conducted through water better than it does through air--farther and faster.

In the same way we breathe air and not water, this begins by understanding that water is more dense than air.  As the image on the right reflects, water density helps capture energy and transmit it much better than air, because the molecules are more tightly packed.

This is the point at which we believe that we should be able to capture much more specific signals from underwater organisms, than we could above the surface.

To that end, and in order to refrain from wasting time and materials, I am currently researching much more specific information on both the transmission of sound energy through water, as well as what attempts have been made to do so, from an engineering perspective. If you would like to follow along, I have cited the sources I am presently reading in order to refine our design idea. I have been reading largely about how sound moves through water, and what approaches have been taken towards acoustic collection, but the bottom resource also discusses how dolphins collect, and since they are our target organism, I'd prefer not to ignore nature's approach either.

Bibliography:
Vigoureux, P. (1960). Underwater Sound. Proceedings of the Royal Society of London. Series B, Biological Sciences, Vol. 152, No. 946, A Discussion on the 'Ear' Under Water (Apr. 26, 1960), pp. 49-51.  Feb 2016.

Martinez, J., et al (2011). Design and Implementation of an Underwater Sound Recording Device. Multidisciplinary Digital Publishing Institute-Sensors. 2011,11,8519-8535; doi:10.3390/s110908519

Branstetter, B. K., Mevissen, S. J., Pack, A. A., Herman, L. M., Roberts, S. R., & Carsrud, L. K. (2007). Dolphin (Tursiops truncatus) echoic angular discrimination: Effects of object separation and complexity. Journal Of The Acoustical Society Of America, 121(1), 626-635. doi:10.1121/1.2400664