Does anyone know of good equipment to measure particle motion in the water, and transferred sound vibrations/pressure through sand underwater (from playbacks)? I have read that some people recommend specific velocity sensors (I assume very expensive) while others recommend accelerometers (not sure what types, but maybe less expensive?). I was hoping someone may have experience taking these measurements and good advice especially about cheaper but reliable solutions. Any advice would be greatly appreciated.
Edit: For depth, not very deep maybe 1-2 meters at most (in a tank) for the water particle motion sensor. For detecting in the sand, it will be about 1-2 m deep and the sand will be only 15-30 cm deep on top of a concrete bottom. The in-water frequency range would be somewhere between 100 Hz - 40 kHz, while the in-sand frequencies would be lower frequencies (e.g., below 1 kHz, likely focusing around 20 - 500 Hz).