A world of silhouettes: Seeing with sound
How do some people use sound to see? Georgia Mills spoke to Lore Thaller and J Steele-Louchert about how human echolocation works...
J - I’m J Steele-Louchart. I’m an orientation and mobility instructor with World Access for the Blind, and I specialise with perceptual mobility techniques, teaching blind people to see through sound and using their cane.
I went blind when I was 12 years old and I had a tiny bit of vision left, by not really any to be functional. I knew about echolocation and other kinds of perceptual techniques from a Discovery Channel special that had been aired in the United States, so I just kind of grew up with it in the back of my mind. And then when I went blind it seemed obvious; I remembered the tongue click, and I remembered a couple of main features of it and I thought well, I don’t have my eyes but I do have my ears and both shut off from a distance perception.
So I started clicking around and experimenting and teaching myself what different distances and textures and things sounded like. Then, when I was 14, about a year and a half later, I went to a conference of this person named Daniel Kish. I started working with Daniel; he started teaching me and, eventually, I became one of his instructors.
Georgia - Could you describe what it’s like to me?
J - It’s like freedom. When I click, I make a really small tongue click, so I might say ‘click, click.’ And what happens is the sound goes out in a cone shape, it tries to wrap around objects and it tries to go through objects, and then it flashes back to me. As I turn my head and I make that noise; I make it every few seconds at most, usually not that often, it gives me all these different pictures of the physical structures around me. I might describe as the world made of mannequins or silhouettes, and I can see all the physical structures. Everything from fences and hedges all the way to buildings, cars, trees, lamp posts, and they all have a very specific dimensionality, texture, density. It is really the world made up of sound.
So, effectively, I’m a low vision person moving through the world even though I’m totally blind. I’ve been totally blind for about five years now and I see with my brain. I see everything that’s around me even though I’m not receiving the information visually.
Georgia - Oh, wow! So there is an image appearing in your head. When did this first happen and did it go straight from nothing to this vision, or did you think this sound means this and it gradually changed over time?
J - That’s a very astute question. It did gradually change over time. When I first started I got sound but not images, and it took a while for it to become true three dimensional, actual images. I remember the first time I ever got a true image, it was when I was on a college campus and I was walking past a building and I clicked, and I saw the building. I didn’t hear it I saw it. My brain filled in the light because I grew up with light and so my brain filled in a visual image in my head, but I very clearly heard all the angles. And the way in which that came about, for me in particular, although it’s a little bit different for everyone, was a long period of building what I call a “sound catalogue” where you do exactly what you described. You kind of discern what sounds go to what distances, what hardnesses and densities, of course, and you build this catalogue of sound where you can assign the sound to a variable and you build your pictures that way. But that turns into an image catalogue through the process of neuroplasticity, the brain actually begins processing these sounds through the visual cortex of the brain, and your integrated visual system creates that visual image even though it’s being processed originally through the ears.
Georgia - What was that like the first time you say this building?
J - Mind Blowing! Even though I grew up with it and knew what it was supposed to be one day. I knew what was going to happen; I’d seen the research. And then it happened and it was - I have no words. It was seeing, it was seeing as a blind person.
Georgia - How does this work? How do our ears enable us to effectively ‘see’? That’s exactly what Lore Thaller, with J’s help is trying to find out.
Lore - What we found is that when we investigate what’s happening in the brains of people who have used echolocation for a while and who are blind, we found that when they listen to these faint echo sounds the parts of the brain that typically process input through the eyes, so light, is very active, so it does seem to pick up on these echoes. At the same time, the part of the brain that processes sound, so the hearing part, is active as well.
What we’ve done then in a second step is we contrasted. Basically, let’s say a person listens to these sorts of echolocation sounds and we’re measuring what’s happening in the brain, and then let’s compare that with what’s happening in the brain when they listen to sounds that do not contain these echoes. It’s sort of still the same sound but it’s just the echoes that are missing. So when we took the difference in brain activity between these two conditions, the part that really came out as still being very responsive to the echoes was this visual part of the brain, and to us that was really surprising. It sort of suggests are they actually seeing with sound; what’s happening? So in research, which we’ve done since then, we’re trying to tease apart what it is that’s actually going on in these sorts of neural structures, and what sort of information that they respond to.
Georgia - Right. Is there some sort of rewiring of the brain going on here then?
Lore - Yes. People who are blind, their brains are organised in a different way as compared to brains of people who are sighted. And that’s just the brain being plastic and adapting to whatever it really has to deal with day to day. Even the brains of sighted people reorganise if you’re learning a new language, if you learn a new skill like playing tennis or something like this, juggling; your brain will reorganise itself. And so this change in the activity of the brain that we’ve observed in these echolocators, that’s very consistent with this knowing that the brain is a plastic organ that reorganises itself.
Georgia - What’s next? What are you looking into at the moment? What do you want to find out?
Lore - One thing we’re very keen on investigating is how this learning actually takes place and how it changes the brain. At this point, most of our work we have taken different groups of people; for example we’ve worked with people who are sighted and then they newly learnt to echolocate, or we have worked with people who are blind and then newly learnt to echolocate, and then we have worked with people who are blind and who are these echolocation experts. And we find these differences in terms of brain activity, in terms of their behaviour, and so on.
One thing we are curious about is let’s say you have a person, and they learn to echolocate, and follow them over a period of time, how does their brain change? Will this learning then actually lead to these changes which we have observed in the brains of expert echolocators/
Georgia - So while we wait to understand more about how our brains can do this, more and more people are taking up the skill. It came be taught quickly, according to J, and is completely life-changing.
J - The word I always come back to is ‘freedom’ when people ask me that question. I mean, what is it to be able to see with your brain? What is it to be able to learn a new area very quickly and efficiently with great accuracy, even from a distance, and to be able to recreate the world without your eyeballs? It’s freedom. It means that I can go anywhere I want and do anything I want. And many blind people can say that, but I can do it very quickly and very efficiently with a great deal of autonomy.
Georgia - But while this may sound, to me at least, like a superpower, J was keen to emphasise this is a skill anyone can learn.
J - It’s not special people out there who are just doing this in very small numbers. There are greater and greater numbers of people who are proving that regardless of your background, it seems very learnable and very teachable as long as you have a structured way in which to do it. I just want people to know that it’s something that they can attain.