Late-night acoustic propagation modeling

The ASA conference session yesterday on acoustic propagation modeling really sparked my interest.  And since I can’t sleep right now, I decided to download Bellhop, and play around with it.  It’s been a long time since I’ve used Bellhop, so I am sort of re-learning the input file format.

I’m working with the Matlab wrapper for bellhop.  It’s not as fast as running the fortran code directly, but it’s easier to configure.  Just for fun, I grabbed the sample Munk sound speed profile, and chopped it off at 2000 meters depth.  I set up the .env file to compute the transmission loss over ranges up to 20 km away.

Here are those results, for 20hz.

I picked this range and depth and frequency to get an idea of the losses that might happen to a fin whale call near our ocean bottom seismometer network.  Of course, this it’s completely inaccurate – I don’t have the right sound speed profile or bathymetry.  Also, I think this model approximates the transmission losses for an infinite CW signal.  Which is not a very realistic approximation of a fin whale call.

Next up:  a better sound speed profile and maybe some bathymetry information.

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