Echolocation-Reconditioning the Senses. Could this help rehabilitate the visually impaired?
Echolocation in the animal kingdom
‘Darkness cast its shadow and left me blind, to discover great wonders of the mind’. (Marcus, 2010).
“Have you ever woken up to hear, above the humdrum of the rising cacophony, the call of the morning birds, or the faint sound of the wind blowing against the window pane, and the walls around you...yes I said walls!”
This may sound bizarre, but there are a handful of people who have developed an extraordinary ability to ‘hear’ inanimate objects, such as chairs, tables, and even the walls surrounding them.
These people are not a new evolved race with special abilities, fitting our comic-book hero description, ‘Daredevil’, a man with the superhuman ability to do back-flips over objects using his innate ultrasonic hearing.
These remarkable people have developed their sense of hearing, using an initial sound stimulus (for example a palatal ‘click’ of the tongue), to locate objects in their immediate environment.
Through practice, these individuals have compensated for their loss of vision with auditory input. They have managed to interpret sound in the form of echoes to give ‘snap-shot’ ‘visual’ impressions of the world around them.
The basic science is that a sound wave deflects off a nearby object, thus resulting in a faint echo. This echo then provides the receiver with information regarding the distance, and dimensions of an object.
Using echoes like this to establish position- sense is referred to as echolocation.
As much as we may like to claim ownership of echo-technology, this technique was first used in the animal kingdom by mammals such as bats, whales and dolphins, to locate food and communicate with one another.
Mankind has adopted this technique in machinery, for example submarines, using sound navigation and radar (SONAR). It has been incorporated into the medical arena, used in pregnancy for anomaly screening and dating scans. It has also been used for echocardiograms to assess the heart muscle wall-thickness and blood flow.
The human ear is a receptive organ for sound, but it also contains fluid (endolymph) within the semi-circular canals of the cochlea in the middle ear, which is responsible for balance.
The average healthy ear detects sounds of approximately 25 decibels and greater. This could potentially be improved through conditioning or ‘fine tuning’ the ear to detect sounds of lower amplitude. However, due to the dominance of our other senses (particularly vision), they only become conditioned to course sounds.
In fairness, this does act in the best interests for a person with vision, considering that vision predominates in many areas of mobility, and if hearing was so sensitive, the brain would have excessive data to deal with, making it difficult to function.
The functional requirements can affect the reliance on the remaining senses, which is why we often comment on people who have become blind to have a super-sensory awareness, or ‘heightening’ of their senses, i.e. touch, smell and sound, to accommodate for the loss of vision.
To develop such a remarkable talent of echolocation takes time, practice and patience to perfect.
Retinoblastoma in a child
Unfortunately for most of these individuals, to have developed their natural hearing to this superhuman extent has come at a severe cost. They have been deprived of their direct vision, which has been a pressing factor in accommodating to their loss of sight.
Complete loss of vision can be dictated by multiple aetiologies. Some of the main causes can arise from cancers (e.g. retinoblastoma), micro vascular disorders (central retinal vein occlusion or retinal artery ischaemia), structural eye complications (retinal detachments), congenital (from birth) i.e. babies born without eyes (e.g. anophthalmia), degenerative (e.g. maculopathy), direct trauma, and progressive systemic causes (e.g. diabetic retinopathies).
To have been ‘robbed’ of such a dependant sense, can potentially leave people vulnerable in their surroundings.
In a more positive light, there are many aids to help adaptation, for example, guide dogs, white walking canes, electronic scanners for food products, voice activated computers, and many more inventive products to assist with daily living. There is even new technology being developed using video imagery and electronic gustatory (taste) stimulation, to assist people with blindness to mobilise independently in their immediate environment.
It essentially works by triggering the occipital cortex of the brain (responsible for vision), via an alternative route (taste receptors), influenced by changes in light, picked up by small video cameras on the head, in other words, it is ‘reprogramming’ the brain to interpret taste in a visual context.
Reconditioning sight to 'see' with the tongue!
The pathway of vision in the brain
Although, such innovation is commendable, it still is in its early phase, and will most likely take many years for these items to be available to the public to purchase.
The concept of echolocation is new to me; I stumbled upon it accidentally, when I saw clips of a few individuals online, who had developed their own method of position awareness using echolocation. The results were impressive, to an extent where you may question, “Has this person really lost their sight? How are they doing that?
One video I saw was of a young teenager who unfortunately had retinoblastoma of both eyes as a child, and had his eyes removed from infancy.
It was remarkable to see in this documentary, the switching on of new circuitry in the brain as he began to notice where buildings were, whilst being driven in his mother’s car. He could recognise changes in sound, as the car drove past buildings, emitting sound from the engine, and he heard the echo of the sound from the nearby buildings.
It showed how this boy made palatal ‘clicks’ with his tongue to assess the echo, which was his cardinal tool for progression of this new ability. This allowed him to walk independently inside and outdoors, to use daily objects (e.g. kettle, cups), and even roller-skate!
This was impressive, but it high-lighted some potential issues that could make such a skill exclusive to this child. This boy had practically been blind from near birth, and he was still a child in the learning-process of life, which is not a commonality of all people with visual impairment.
Echo-location is not an ageist technique, although due to the natural biological processes, it will favour certain age-groups more than others. It relies on the brain to learn new information and interpret it (re-conditioning), and the sense of hearing is crucial for the reception of sound. This can be portrayed in young children, for which their brains acts like a ‘sponge’ for new information. The brain is continually growing and re-conditioning itself. Evidence of this is seen using Computed Tomography (CT) scans, which show gradual enlargement of the cerebral hemispheres (2 ‘half-brain’ segments), reflecting the new ‘wiring’ of the brain as the child grows and learns information. In fact, for certain processing in the brain, for example vision, it is accomplished relatively early on in life (before 5 years). This is the rationale for when children below 5 years, have certain eye problems, for example squints; most effort is done to ensure corrective eye-patches are not used for prolonged periods, as when the child reaches the ages of 6-7 years (‘Critical age’), the vision should be completely established neurologically. If the child had no sight in either eye before this for a lengthy period, they are at the risk of permanent blindness due to the absence of electrical connections (synapses) formed in the brain.
Although, this is similar with the body’s other senses; the difference with hearing is that we can recondition our brains response to the information.
A common example of brain-reconditioning is our ability to ‘pick-out’ the calling of our name in a loud room. This is because our brains have re-wired themselves to alert our attention to our names, as we associate them with a personal significance and change, hence conditioning.
A similar feature was described in Pavlov’s dogs’ theory; whereby dogs became conditioned after hearing a bell ring (indicating time for feeding) on repeated attempts (re-conditioning), which triggered salivation. This is a programmed response.
So there is no doubt that we do have the ability to re-wire our brains essentially, and as one of the most sophisticated organs; it has become very accustomed to change and constant adaptation.
Honestly speaking, I was still sceptical regarding the potential for echolocation to be taught to other people with visual impairments, considering so few people acquired this rare skill.
It was not until I saw another video online about another man who was visually-impaired, who used echolocation in practice, as he demonstrated riding a push-bike. The other remarkable fact was that he was able to teach other people with visual impairments how to use echolocation.
This was the first point at which it made me think, ‘maybe this could actually be used to rehabilitate people with blindness’.
This man is Daniel Kish. Here is a video illustrating his use of echolocation.
Echolocation in practise
After seeing this video, I was more confident that such a skill, with use of the existing aids for the visually impaired, could potentially improve the quality of life for many such people in the community.
I e-mailed Daniel with some questions I had, regarding his experience with the use of echolocation, and this is a summary of his replies:
My questions for Daniel Kish
1. Did you always have a visual impairment? At what point in your life did you discover echolocation?
“I lost my first eye at 7 months and the second at 13 months from retinoblastoma. I've been using echolocation ever since. My earliest memories are when I was about two, and I used it to discover that there were things on the other side of a wire fence. I climbed into the neighbour's garden to investigate, and noticed things through the fence into the subsequent neighbour's garden. I don't know how many houses down I was before someone had me returned home”.
2. Have you successfully taught echolocation to people who have recently lost their sight?
“Yes, but it takes longer”.
3. Do you think echolocation would still be successful in people who are registered visually impaired, but may have some degree of visual acuity, i.e. detect light
“It depends on the type of visual impairment. Some people with field loss have found echolocation to be useful in supplementing what they can see”.
4. Do you think echolocation has a greater success rate in younger people? How old is the oldest person you have taught? How young is the youngest?
“The youngest person I taught was about 18 months and the eldest, maybe 68 years of age. The youth are usually more easily adaptable, but the real key is motivation”.
5. What about people with hearing aids? Have you attempted using a hearing aid to echolocate for experimentation? Does it affect the quality of the echo?
“It works fine, depending on the nature of the hearing loss. In the ear, aids work best, but some people have adapted to behind the ear aids as well”.
6. For a good student, how long on average would it take to develop echolocation?
“It would take about 24 hours to get the ‘ball rolling’, and maybe a few months of concerted practice to cement the skill”.
7. What main exclusion criteria would have to be set to prevent disappointment of failure? I.e. severely impaired hearing, other complex medical history (e.g. dementia in the visually impaired person)
“It is very difficult to say. Obviously, the more complex the profile, the longer it may take, or the more we need to be creative. I'd say perhaps the biggest issue would be if there are attention disruptions or deficits in the student. Echoes are fairly subtle, and the brain needs to quiet down and focus. So, attention issues, or chronic anxiety makes the process more challenging”.
8. Do you think echolocation could be used effectively to rehabilitate the visually impaired in general?
“Definitely, it’s a way to see!”
Daniel is currently in the UK. He is setting up conferences and programmes to promote and teach echolocation, with hope that these will become establishments to rehabilitate the visually impaired population.
There are international conferences planned in the future to increase awareness of echolocation, for which you can read more information on the website:
It also explains the intricacies of the FLASH SONAR PROGRAMME, and gives more information and resources on echolocation, including advice on how to become involved, or offer a donation to the cause.
There appears to be a window that has opened up in the reformation of rehabilitation for the visually impaired.
Echolocation should not substitute, but complement all the technology available to assist the visually impaired.
If this article has only increased awareness on such a relevant topic to so many peoples’ lives, then it has fulfilled its objective. I hope that it may spark some interest in some influential groups and give a new insight into the loss of sight.
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