Intricate Sound Sensor Inspired by Bat Ears

Innovation: Academia

Virginia Tech

2021

Image: rigel / Unsplash / CC BY SA - Creative Commons Attribution + ShareAlike

Send Sound Signals

Many living systems send auditory signals to communicate with others, including to attract, announce, or warn. These sounds must be audible to the intended recipient in a variety of conditions, such as in wind, water, and solids. As a result, each living system has specific sounds best adapted to its environment. For example, some birds live in loud habitats, like those alongside noisy streams or in windy areas. These birds use sound frequencies that can be heard by other birds over competing environmental noises.

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Sense Sound and Other Vibrations From the Environment

For living systems, sensing sound and other vibrations is important for communicating and detecting conditions within their environment. Living systems must locate a signal’s source so that they can move toward it (such as when it is food or a potential mate) or away from it (such as when it is a predator). To prompt an appropriate response, living systems must sense these signals, recognize their amplitude or volume (which is sometimes very low), and determine their direction. Living systems must be attuned to signals relevant to them and able to distinguish these from irrelevant sounds to avoid expending unnecessary energy. For example, owls’ ears are asymmetrically placed. This enables them to detect sounds more accurately, which helps them locate small prey at night and avoid wasting energy chasing down irrelevant sounds.

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Sound sensor from Virginia Tech uses machine learning to more accurately interpret incoming sound waves.

Benefits

Reliable
Autonomous
Accurate

Applications

Medical implants
Surveillance
Security

UN Sustainable Development Goals Addressed

Goal 9: Industry Innovation & Infrastructure

The Challenge

Traditional sound sensors are often designed simplistically, to streamline the interpretation of the sensory outputs. Unfortunately, many sensors are unable to accurately identify the source of a noise because they are not good at eliminating extraneous information.

Innovation Details

The sound sensor consists of a synthetic bat ear and a microphone. The synthetic bat ear flutters as it hears a sound, funneling the sound waves toward the microphone. This microphone is connected to a system with a deep neural network, capable of learning sounds. The sensor is mounted on a rotating rig with a laser pointer, so when it “hears” a sound, it immediately rotates and points to it. The sensor can pinpoint the noise within half a degree, more accurately than humans, who are capable of pinpointing a sound within seven degrees.

Biomimicry Story

Bats use echolocation to pinpoint the location of prey and obstacles as they navigate through the air. To echolocate, bats send out sound signals from their mouth and nose. The sound signal travels through the air, bounces off the object, and returns to the bat, informing the bat of the location of the object. Essentially, bats use their ears to “see” their environment, much like how ships use sonar.

See Related Strategy

an egyptian fruit bat hangs upsidedown with open eyes

Biological Strategy

Off-Target Clicks Help Fruit Bats Find Food

Egyptian fruit bat

These fruit-eating bats home in on a meal by aiming sound waves to the side of their intended target, then adjusting their path to reduce the difference in timing between the waves bouncing back.

References

Journal article

Integration of deep learning and soft robotics for a biomimetic approach to nonlinear sensing

Nature Machine Intelligence

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