The "Miami Sound Machine" acoustic projector being readied for a test.
One group of investigators within the Applied Marine Physics (AMP) Division of the Rosenstiel School of Marine and Atmospheric Sciences (RSMAS) is concerned with the physics of sound and its use as a measurement tool for learning more about the ocean environment. We design and use underwater acoustic instrumentation that range in size from hydrophones (underwater microphones) a few centimeters long to the "Miami Sound Machine" (see photo on right) acoustic projector (underwater speaker) that is over 6 meters (18 ft) long and weighs in at 17.7 kN (6200 lb) in air. Our research ranges from basic studies of how sound behaves in the fluctuating undersea environment to the use of sound as a remote sensing tool to estimate the number of Atlantic Bluefin tuna that migrate through an area or the mass transport of the Gulf Stream. We’ve traveled to the Arctic and Pacific Oceans to conduct our research and in the coming years have plans to study regions in the Mediterranean and South China seas. We work at depths that range from a few tens of meters to 6 km (3.7 miles).
While electromagnetic radiation weakens rapidly in the ocean environment, making tools like radar difficult to use, the focusing effects of the deep ocean sound channel make it possible to send low frequency sound around the world. Sonar pulses are used by dolphins to sense the world around them, and are being used by humans in much the same fashion. We can measure the depths of the ocean, find resources like fish and oil, and even measure ocean temperature by use of relationships between the temperature of the ocean and the speed at which sound moves through it. While we’ve been studying sound for hundreds of years there are still new discoveries to be made. Computer models that predict how sound behaves in the ocean are being improved daily, but can still not explain much of what we observe in our experimental programs.
Acoustic test range being installed off the coast of Ft. Lauderdale as part of the South Florida Ocean Measurement Center (SFOMC)
Ocean Acoustic Observatory
Probe Source prototype.
The Ocean Acoustics Group conducts research funded by government agencies like the Office of Naval Reseach (ONR) and the National Oceanic and Atmospheric Administration (NOAA) and joint projects with partners from government laboratories, other universities and industry. We are currently working with the South Florida Ocean Measurement Center (SFOMC) on a major project to install arrays of underwater hydrophones (see picture on left) that will permit us to conduct shallow water acoustic research in real-time and access our data via the internet. Another project, being conducted in cooperation with Engineering Acoustics, Inc., is the development of a small acoustic projector system called the "Probe Source" (see photo) which may someday be launched from submarines and surface vessels around the world and used to learn more about our ocean environment.
A new project being proposed to the Navy, involves the expansion of our current hydrophone array installation from 96 hydrophones to several thousand hydrophones cabled to shore off the coast of Ft. Lauderdale. These passive (listen only) systems will be used to learn more about ambient noise as well as for general shallow water propagation studies. See the linked powerpoint presentations for more information:
description Powerpoint presentation comments Program Overview briefing #1 updated 6 March 2001 General system architecture briefing #2 Construction and deployment techniques briefing #3 Latest revision: 6 March 01