Tuesday, September 30, 2008

Echolocation vs. "Facial Hearing"

Head facial nerve superfical branchesImage via Wikipedia

Echolocation is a phenomenon that is perceived in different ways by different people. Some people refer to it as a pressure felt on their face. This is referred to as "facial hearing" and is actively used by many blind people. This is not a different phenomenon than echolocation, it is simply a different perception of it. All people experience the world differently and will describe their experiences in the way that best suits them. Technically, echolocation IS a pressure on the face; it's in the form of sound waves reflected back toward you.

It's my hypothesis that physical nerve receptors in the face are much less adept at distinguishing pressure than the cochlea in the ears since the ears are naturally a very precise and delicate instrument. It's debatable whether or not this "facial hearing" is the cognition and perception of actual nerves in the face from sound pressure, or if it is just a perception based on auditory input, but regardless, I would estimate that echolocation while in the mind set of focusing attention on the hearing would be more accurate than focusing attention on the facial nerves.

I have personally noticed more of the facial pressure when objects become closer to my face. Using echolocation and focusing on hearing, I can usually distinguish walls within 10 feet. But no facial pressure becomes obvious until about 2 feet. Once I come within 2 feet of something, it quickly becomes apparent that I should watch out.

I'm certainly still just a beginner so I will be conscious of both of these perceptions to see if one evolves more than the other, or whether they can be used for different things.

Friday, September 19, 2008

Learning Echolocation on Foot

A Wall.

Image via Wikipedia

Walking around on your own and trying to echolocate is much different than driving in a car. The engine noise of a car offers a very good tone for listening to as it reflects off passing objects. I've tried a couple different methods so far for creating a noise that I can interpret. I've tried clicking, and I've tried just listening to my footsteps, and I've tried listening to my pants swish against themselves. Really, we're looking to interpret the reverb characteristics of the room or hallway.


I've got long straight hallways in my office building that have flat walls. Quite distinct as far as reverb goes. I've managed to walk down the hallway and notice when I'm approaching one of the sidewalls. But it doesn't become overly present until I'm less than a foot and a half away, at which point I can put out my hand to my side and touch the wall with decent accuracy. Obviously it's best to practice this when there aren't too many other noises around you like people talking, wind or machinery.

I think one of the things that helps with this is that the walls are directly to the side, making them a direct shot to the ear. Objects and walls directly ahead seem like they're a bit more difficult to detect. I'll have to work on that, it seems like it might be an important part...

Objects seem to be further than they sound

I find that other noises, like people walking or talking seem much closer than they actually are. This is probably because I am focusing on hearing everything and therefore everything is a bit amplified.

Sound Landmarks

There are certainly objects which do make noise. Printers, machinery, water bubblers etc. which can not be ignored. I think these objects will play a critical role in navigation. Of course, this will probably only work if you are in an environment that you are already familiar with. IE, if you know where the printer is, you probably know on which side of it you should be walking, and approximately how far from it you should be. But I think these things are certainly useful and we should be using ALL of the sounds available to us to help locate.

Thursday, September 18, 2008

Beginner Echolocation Lesson #1 - Echolocating While Riding in a Car

As I ride to work in the morning, I 've been leaving the passenger's side window open. This is a good way of directing my listening attention in one discrete direction. Also, being in the car works well, because it emits quite a bit of sound that is quite constant and covers a fairly broad spectrum of audio. And it is fairly quiet inside the car, so it makes it easy to hear the sound reflections coming in through the window. As I drive by objects on the side of the road it's apparent that they are detectable via audible variances, but I can't decipher what they might be quite yet. It seems that practicing echolocation will at first involve relating sound reflections to objects that I can otherwise identify and then relate the sound patterns to them. If we could remember these patterns we could apply them to any similar object we encounter in the future.
Here are a few things I could detect and couple of rules that seem to make sense:

Telephone Poles

Since a telephone pole is round the sound bounces off of it in all directions equally. The sound reflection pattern can be described as a "swell". As you approach the pole you can hear reflections gradually fade in and peak as you pass it and fade out evenly. This would be the same for any round object that you are passing along the direction of its curvature. The object, and this goes for all objects as far as I can tell, will have a greater magnitude of sound returning to your ear the closer you are to it. Sound degrades (or disperses) over distance so it makes sense that the closer you are the "more" sound waves you will be receiving.


I was struck when I noticed the difference between telephone poles and mailboxes. The response curve of a mailbox is generally slightly smaller due to it's size (of course they are usually closer to the road than poles) but the interesting thing was that since they have a flat
face (the door) the response curve is more of a square wave than a sinusoid (like the telephone pole). In other words, the amplitude of the sound reflection increases quickly when you are
exactly perpendicular to the flat face, and then drops off quickly once you pass. So they have a much more brief presence.

Parked Cars

Of course moving cars are easy, they emit their own sound! But parked cars are unique in that you can recognize the metallic material they are made of because of the higher frequencies they reflect. For some reason it seems that wooden fences, tree clusters, and trash cans don't reflect these higher frequencies. This is probably due to there more absorbative properties. When frequencies start getting absorbed, usually the higher once are first to go since low frequencies, by nature, travel greater distances.


Flat fencing is generally fairly distinct, switching "on" quickly when you approach and "off" quickly when it ends, and generally remains very constant when you are passing it. Wooden fencing doesn't generally reflect the higher tones.
Metal fencing, in particular, the "3"-shaped metal extrusion gaurd rails that you see everywhere, is different in that it seems to reflect the lower frequencies and the higher frequencies (probably due to the non-absorbative material) but there doesn't seem to be a lot of
mid-range tones being reflected. I don't have an explanation for that, and I may be wrong about it. Maybe I'll record some of these and do some analysis.
I plan to continue my findings here as I discover them. If anyone has anything to add to help me out I would much appreciate it if you left comments!

Wednesday, September 17, 2008

A Brief Introduction to Human Echolocation

Echolocation is the method of interpreting sound that reflects off of surrounding objects in order to distinguish where and even what they are. It's like what dolphins, bats and whales use, but their frequencies are different than the ones we can detect. Sound is very similar to light in that it is a wave of energy that bounces off objects and reflects some properties of the object in the way that it bounces. We have detectors, called "ears", that interpret all of the sounds around us, however, most of us have not put to use our ability to "echolocate" using them. Many blind people utilize this tactic via listening to the reverberations of their own footsteps, or by making a clicking sound with their mouth.

What would be the good of having taste buds and just not bothering to use them?

Here's a pretty remarkable story of one kid, Ben Underwood, who is excellent at echolocation.

There is another man by the name of Daniel Kish who has done a lot of work to encourage blind people to use echolocation more effectively for navigation in everyday life. He has started a non-profit organization called World Access for the Blind, and promotes a "No Limits" approach to life for the blind. He leads blind people on hiking expeditions and even mountain biking. You can check out the website for the World Access for the Blind for more information.

Imagine if we all had the ability to echolocate. This is a big step towards putting one of our senses to greater use. What would be the good of having taste buds and just not bothering to use them? Isn't this what we've done? We have this power to use our ears as a backup to our eyes should we ever be in the dark, or end up without the use of our eyes.

I've been trying to learn this a bit myself and I'll keep a list of my findings here. I'm not sure how easy it will be for seeing people to accomplish this, but like anything, it's only a matter of desire to learn, dedication and practice.

Keep reading the rest of the articles for summaries of my findings and learnings as I go. Feel free to leave comments if you have any tips or want to share anything.

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Free 10-Minute Audio Lesson: Learn the Echolocation Click

Learn echolocation clicks with a free audio lesson
Learning how to click is one of the first steps to becoming an effective echoloator. This lesson provides clicking samples of a variety of different clicks and descriptions of when they might be most useful. This lesson has been used by O&M instructors all over the world.

Despite popular belief, it's easy to make your clicking quite subtle or unnoticeable even in quiet settings. There are many different clicks for different situations. I explain all of these in great detail and give examples of where, why and when they can and should be used.

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