Acoustic Spreading…what's that?

Well the Beam Reach students are about to figure that out. It’s amazing to me how quickly students learn in this hands on program. The instructors provide them with an introduction, show them how things work and why, and then help the students in the field. Some of the students know almost nothing about acoustics when they arrive and leave knowing how to gather acoustical data, interpret it, and use it to draw conclusions.

I’ve been a part of Beam Reach for a little over two years now (I’m in the office) and, while some of this rings familiar, it is still so complicated to me because I’m not a scientist and I haven’t gotten to do the program. (I’m finding it more and more difficult to get away for a week, much less ten of them!)

So it is with true joy and amazement that I watch our students absorb this information and become confident in their abilities. Here’s a sample from a beginning exercise they do. To some of you out there this will make sense, to the rest of us, well we can only be grateful that somebody understands it.


Dear students,

Congratulations on making it through the calibration and spreading sessions
on the dock this morning, as well as the very brief Matlab tutorial.

For your exercise that you should hand in before 5:30 this afternoon (via
email) you should include the following information:

The metadata for the two experiments.
The calibration factor for each of the 4 hydrophones and an explanation of
how you calculated it.
The received level (in dB re 1 microPascal) of each hydrophone for the
spreading experiment.
A plot of those received levels vs the log of the distance from the source.
A regression line through those data points with the slope, R-squared value
and the source level (in dB re 1 microPascal @ 1 m).

Just in case your confused; the following channels correspond to the
following wav files:

Calibration ex:
A01_1.wav       Ch 1
A01_2.wav       Ch 2
C01_1.wav       Ch3
C01_2.wav       Ch4

Spreading ex:
A03_1.wav       Ch1 (the farthest hydrophone from the speaker)
A03_2.wav       Ch2
C03_1.wav       Ch3
C03_2.wav       Ch4 (the closest hydrophone from the speaker)

Also as a reminder, the energy exercise is Due at 8:30 on the
16th.  Because we will be off island this weekend and again on Tues to pick
up food for our adventures at sea, you should plan on collecting the data
that is needed for the energy exercise today or on Monday (look back at the
excel sheet that Val gave you for a reminder).

I'll post next week's syllabus in S1 so you have an idea of what will be

Good luck


Jason Wood, PhD, Instructor
Beam Reach,
Marine Science and Sustainability School

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