Here’s how barn owls can help advance navigation technology

Washington: While owls might not affect the human race significantly, these nocturnal species can form the basis of electronic navigation devices, a new study has revealed.

Findings of the study were published in the journal ‘Nature Communications’.

“We were already studying this type of circuitry when we stumbled across the Jeffress model of sound localisation,” said Saptarshi Das, assistant professor of engineering science and mechanics.

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The Jeffress model, developed by Lloyd Jeffress in 1948, explains how biological hearing systems can register and analyse small differences in the arrival time of sound to the ears and then locate the sound’s source.

“Owls figure out which direction the sound is coming from to within one to two degrees. They use this ability for hunting especially because they hunt at night and their eyesight isn’t all that good, “explained Das.

The ability to use sound to locate relies on the distance between the ears which is quite small in barn owls. What is more interesting is that if the owl is facing the sound’s source, both ears get the sound simultaneously. On the other hand, if the sound is coming from the right, the right ear registers the sound slightly before the left.

Speed of sound is faster than the owl’s nerves can function, so after the owl’s brain converts the sound to an electrical pulse, the pulse gets slowed down.

In this study, Das and team created an electronic circuit that can slow down the input signals and determine the coincidence point, mimicking the working of the barn owl brain.

The team created a series of split-gate molybdenum sulfide transistors to mimic the coincidence nerve network in the owl’s brain. Split-gate transistors only produce output when both sides of the gate match, so only the gate tuned to a specific length will register the sound. The biomimetic circuitry also uses a time-delay mechanism to slow down the signal.

While this proof-of-concept circuit uses standard substrates and device types, researchers believe that using 2D materials for the devices would make them more accurate and also more energy-efficient, because the number of split-gate transistors could be increased, providing more precise coincidence times.

“In effect, nature has done most of the work for us. All we have to do now is adapt these neurobiological architectures for our semiconductor devices,” said Das.

To actually navigate or locate, a device would need to know the height of the sound source as well. Saptarshi Das noted that height is a property of the intensity of sound and researchers are working on this aspect of the problem.

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