Making a map of the ocean floor with sound seems almost counterintuitive. Sound, not light, radar, or cameras. Pulses of vibration are sent down through dark, pressurized water. They hit sediment and rock and bounce back up, carrying information about a world that most people will never see. The Danish acoustic technology company RESON, which is now part of Teledyne Marine, has built its whole fifty-year history around this idea. The company has been around for fifty years this February. It is a quiet event, but people in the marine science world seem to feel it.
When RESON was started in Denmark in 1976, it wasn’t because of a lot of hype. As with most long-lasting engineering firms, it grew by helping people in tough environments solve real, specific problems. These are real customers: hydrographic surveyors, offshore engineers, naval operators, and dredging crews. They are professionals who work in places where broken equipment can really hurt people. RESON has made more than 20,000 echosounders for mapping the seabed over the past fifty years. That number doesn’t seem important until you think about what it stands for: coastline after coastline, ocean trench after ocean trench, slowly turned into data that someone, somewhere, could use.
It’s important to take a moment to think about the science behind this technology, since it’s easy to forget how strange and beautiful it is. Light doesn’t move very well through water. Once you get below fifty meters, it’s hard to see. There is no sunlight below 1,000 meters, which means that cameras aren’t very useful for taking pictures of the deep ocean. Sound, on the other hand, acts in a very different way. Every second, loudspeakers underwater shake a million times, sending waves through the water until they hit the bottom of the ocean and bounce back. By measuring the return time and the strength of each echo, scientists can figure out what’s below and how it looks and feels. It works a lot like how bats have used echolocation for millions of years. RESON just figured out how to do it reliably, with engineering precision, in depth, on a large scale, and with great accuracy.
RESON was different from the start because it promised to keep all of its research, development, production, and service in Denmark under one roof. This seems to still be a big part of the company’s culture. That kind of integration doesn’t happen very often anymore. It creates a certain kind of institutional knowledge that is hard to put into a spreadsheet. These engineers built many of RESON’s early systems and many of them are still there or have been there long enough to pass on their hard-won knowledge. Teledyne Marine Europe has been led by Ole Søe-Pedersen since 2011. At the anniversary, he made it clear: “What has never changed is our focus on building acoustic and sonar technologies that solve real operational needs.” There’s something very old-fashioned about that sentence. However, the performance in the field speaks for itself—RESON hydrophones that were put in place more than thirty years ago are still working.
The technology’s uses have grown in ways that most people probably couldn’t have imagined in 1976. The SeaBat platform, which is RESON’s most popular multibeam sonar system, has pretty much become the standard in its field. Researchers have used similar tools to find the underwater landslide that caused the 1755 Lisbon tsunami, which was very destructive. Other groups have used acoustic sensing to look inside rusting chemical weapons barrels that were dumped in the Baltic Sea after World War II in order to figure out how dangerous they are without touching them. These aren’t small steps forward. These are really new features that come from fifty years of improving the sound.
There’s another bigger point to make here. The surface of Venus is more interesting to us than the ocean floor on Earth. About three quarters of the Earth’s surface is water, and large parts of that are still not mapped at a useful level of detail. RESON’s work fills in that gap, but it does so in a way that keeps it from getting too big. Every echosounder that is used, every survey that is finished, and every seabed image that is made with more accurate details is a small fix for a very big problem. Celebrating that with a bucket hat challenge is a strange idea. For its anniversary, RESON also started this challenge, asking people to take pictures of themselves in strange places while wearing their RESON hats. As a company that makes sonar, it seems a bit silly. That could be the point, though.
Several of the company’s new products will be shown for the first time at Oceanology International in London in March. There aren’t many details out there yet because the company still thinks that a reveal means something. It will be interesting to see where fifty years of experience with sound takes us next.
