Nov. 3, 2011Vol. 42, Issue 2

Listening to the Song of the Sea in Chico, California

by Kris Walker, University of California, San Diego and Jeff Mott, California State University, Chico

Pulling special microphone (long tube) through triangular, bear-resistant cage. From left to right are Jeff Mott, Heinz Wuhrmann, Joel White, Kris Walker, and Brendon Armstrong. Paul Maslin and Bruce Gallaway also assisted in the project. Photo taken October 2010.

Humans cannot hear the song of the sea. The ocean’s natural frequency is simply too low for the human ear to detect.  However, special microphones can listen to the ocean quite well. In fact, the ocean’s natural frequency is so low that these sensors can hear the ocean thousands of miles away, just as you can hear the low-frequency rumbling of thunder from distant lightning.

In October 2010 four microphones were installed at Big Chico Creek Ecological Reserve (BCCER) as part of a NOAA-funded collaboration between the University of California, San Diego and California State University, Chico (see photos at left and right). This group of microphones is part of a larger network of microphones within the western United States. The project has two goals. The first goal is to use these microphones to locate the source of the ocean sound in the eastern Pacific Ocean. Just as having two ears allows you to pinpoint the location of the ringing wine glass with your eyes closed, having more than one microphone allows scientists to locate where the ocean sound is coming from.

Completed installation of microphone shown in Figure 1. Photo taken November, 2010.

The primary source of ocean wave forecasts for the inshore and offshore Pacific is NOAA. These forecasts come from models of the ocean waves, which are created in part by the heights of waves measured by buoys. Verifying the accuracy of these models is important because commercial and recreational human activities both near the coast and hundreds of miles off the coast rely on these models to make important decisions. One could put hundreds of thousands of buoys in the ocean to verify that these models are accurate, but that would be prohibitively expensive. However, these models can predict where ocean sound will come from. Therefore, the second goal of this project is to verify that the NOAA wave models are accurate by comparing the observed sound locations to the predicted ones.

This project is a work in progress. Preliminary results were presented at the American Geophysical Union meeting in San Francisco in December 2010.

There are many people who assisted in this project. But we want to especially thank Brendon Armstrong (1987–2011). Brendon prepared BCCER for the microphones, helped install them, and was the primary caretaker. His dedication and hard work was critical to the success of this project, and we will miss him dearly.