The recent discovery that when using echolocation, dolphins actually emit two intertwined ultrasound beams at different frequencies at slightly different times, could allow scientists to develop new ultrasound and sonar equipment.
Researchers from Lund University used a mathematical algorithm to successfully disentangled and read the overlapping signals, a discovery that could inspire sharper image quality on ultrasound technology to measure the thickness of organ membranes deeper inside the body than is currently possible.
“It works almost like a magic formula! Suddenly we can see things that remained hidden with traditional methods,” Josefin Starkhammar, a researcher in biomedical engineering at Lund University, said in a statement.
The new discovery may also lead to improved sonars and echosounders—the equipment used for orientation at sea to read the undersea environment and track shoals of fish.
“Here we could copy the principle of using sound beams whose frequency content changes over the cross-section,” Starkhammar said. “As a first step, we will rebuild our own equipment which is based on the pulse-echo principle.”
Dolphins are known to be particularly skilled in the ability to orient themselves, find food and communicate with one another compared to other sea-based creatures.
The new calculations show that dolphins emit the two signals at different times, with one followed closely by the second signal. The researchers also discovered that the sound frequency is higher further up in the ultrasound beam, producing a lighter echo within the beam.
The researchers used a measuring instrument with 47 hydrophones to capture sounds in water in many different frequencies over a whole surface in Kolmården Wildlife Park in Sweden and in wildlife parks in the Bahamas, Honduras and California.
“High and low frequencies are useful for different things,” Starkhammar said. “Sounds with low frequencies spread further under water, whereas sounds with high frequencies can provide more detailed information on the shape of the object.
“In fact, it is quite strange that the dolphin emits two different beam components, as they come from the same organ,” she added. “We would very much like to find out how this particular event comes about.”
According to Starkhammar, the slightly separated signal components could enable the dolphin to quickly gauge the speed of approaching or fleeing prey because the variations in frequency provide more precise information on the position of an object. However, this is not yet confirmed.
The researchers now plan to test whether the technology can be a replacement for the destructive testing of roads by rapidly obtaining an image of what a newly built road looks like under the surface without needing to drill for samples.
Dolphins also benefit from scientists having a better understanding of their echolocation capabilities.
“With greater understanding, we can protect them from human activity which could damage, disrupt or disable this ability, such as noise from shipping, pile driving in the water, underwater blasting, powerful boat sonars and searching for oil under the sea bed using acoustic methods,” Starkhammar said.
The study was published in The Journal of the Acoustical Society of America.
