Bio-mimicry
Bio-mimicry
The many problems that plagued mankind evolution have led us to observe how these problems have been solved by nature. Animals have therefore always been an important source of inspiration for engineers (and those who preceded them). For several years, this approach has been called: Bio-mimicry.
" Learn from nature, that's where our future is. "
Leonardo DeVinci
Motivations
All animals (and so do we) have three major concerns:
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reproduce,
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escape predators,
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detect prey.
In that perspective two types of organs have developed:
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Eyes to see what is happening in the direction where you looking,
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Ears (or sound sensors) to hear what we cannot see.
All animals (as well as us) have therefore developed protective strategies:
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listening to the world around (even at night),
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Assess the situation by looking at what caused the sound just heard and that is not part of the usual environment.
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Act accordingly.
Our eyes and ears are inseparable partners for our safety. In addition, echolocation determines the direction of a source of short sounds. CCTV already uses vision, how can it leverages hearing?
Some animals have proven to be much more efficient at hearing and alerting than us: thus dogs are our best partners. Beyond exceptional hearing, which balances for mediocre vision, dogs have a remarkable capacity for learning which allows it to be self-sufficient and versatile.
Dogs are clearly conditioned by their training as well as the attitude of their masters. A dog learns to integrate into the human society around it. However, alerting is an instinctive act that must be of the reflex order to be fast enough.
Sound is basically just a variation in air pressure (or in the environment in which it propagates), it is our brain that will make it into a sound by interpreting this variation. The detection of this variation is already information and it does not depend on our culture or our habits. It is the primal and universal alert of all those who have ears.
Auditory Evoked Potentials (AEP)
The study of the functioning of the human ear has been carried out on the basis of evoked potentials, detectable in the electroencephalogram, provoked by auditory stimuli of short duration (clicks). These studies make it possible to detect flaws that may occur in the chain of acquisition and processing of sounds by the brain. These studies have led to the development of specific diagnostic equipment.
A study conducted by Bao-Trân Truong and Coralie Damenet at the ENT department of the Angers University Hospital has shown that there are different forms of AEP:
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Early latency AEP (PAEP): less than 10ms,
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Average latency AEP: between 10 and 50ms,
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Late cortical AEP: more than 50ms.
Instinctive alerting may be related to AEPs while sound interpretation is related to late cortical AEPs.
Location of sound sources and Acoustic Antennas
The design and use of acoustic antennas is the continuation of acoustic direction finding techniques implemented during the first and the beginning of the second world war for aircraft tracking. It is the notion spread of stereophony and the directionality of microphones.
Our two ears (and our adjustable head) allow us to determine the approximate direction of short sounds sources .
An acoustic antenna consists of a set of microphones (used as pressure sensors) that measures the the acoustic field amplitude perceived at a given point.
The shape of the perceived acoustic field allows:
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either to listen in a given direction,
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or to determine a sound source direction.
