Coupling a hydrophone

[h.r.baillie-johnson]

I'm waterproofing a small microphone for use as a hydrophone. it will
need to be very waterproof, so I thought of encapsulating it in either
epoxy or silicon sealant. The former is hard, the latter rubbery. Can
anyone suggest which would be the better material to use to achieve
efficient acoustic coupling? I am recording audio frequencies.
Thanks for any advice, -h.
--
h.r.baillie-johnson

[William R. Penrose]

This brings to mind a very old article in Scientific American's Amateur
Scientist column, maybe in the '70's. The hydrophone was sealed in a bottle
of silicone vacuum pump oil, which apparently makes a reasonable
low-attenuation coupling with water, even through glass.

Bill

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