利用动物实验改进超声波技术

Sonar and ultrasound, which use sound as a navigational device and to paint accurate pictures of an environment, are the basis of countless¹ technologies, including medical ultrasound machines and submarine navigation systems. But when it comes to more accurate sonar and ultrasound, animals' "biosonar" capabilities² still have the human race beat. But not for long. In a new project that studies bats, dolphins, and mole³ rats, Prof. Nathan Intrator of Tel Aviv University's Blavatnik School of Computer Science, in collaboration⁴ with Brown University's Prof. Jim Simmons, is working to identify what gives biosonar the edge over human-made technologies. Using a unique method for measuring how the animals interpret the returning signals, Prof. Intrator has determined⁵ that the key to these animals' success is superior, real-time data processing. "Animal 'echolocations' are done in fractions of milliseconds, at a resolution so high that a dolphin can see a tennis ball from approximately 260 feet away," he says, noting that the animals are able to process several pieces of information simultaneously⁶（同时地） .

Their research, which has been reported in the Journal of the Acoustical⁷（听觉的） Society of America and presented at the 2010 and 2011 MLSP conferences, could lead to cutting-edge navigation systems and more accurate medical imaging.

Detecting "shape" from sound

Biosonar animals send ultrasonic⁸ sounds called "pings" into the environment. The shape of the returning signals, or echoes, determines how these animals "see" their surroundings, helping⁹ them to navigate¹⁰ or hunt for prey¹¹. In a matter of tens of milliseconds, the neurons in the animal's brain are capable of a full-scale analysis of their surroundings represented in three dimensions, with little energy consumption. Even with the aid of a supercomputer, which consumes thousands of times more energy, humans cannot produce such an accurate picture, Prof. Intrator says. With echolocation, a bat can tell the difference between a fly in motion or at rest, or determine which of two fruits is heavier by observing their movements in the wind.

Intrigued¹²（好奇） by the quality of the natural world's biosonar over its human-made equivalents, Profs. Intrator and Simmons set out to study how biosonar animals perform echo location so quickly and accurately¹³. Using an electronic system, they altered the frequency and noise levels of the echo returned to the animal.

By manipulating the echo, the researchers could determine what factors of the returning signal reduced an animal's ability to correctly analyze¹⁴ the returns. This in turn led to a better understanding of how the returning echoes are represented and analyzed¹⁵ in the animal's brain.