Beginner Lesson #4 - How to Tune your Senses for Echolocation - Exercise #2

<<--Back to Exercise #1

Sensitization Exercise #2: Listening to your Computer Monitor

This exercise will actually focus on hearing and interpreting the location of objects with your eyes closed. This is the basis for all echolocation and the principles from this lesson can be applied from here on out as you hone your skills.

1. Start by making a "ssshhh" noise with your mouth. You can also use "aaahhh" or many other steady tones.
2. Bring your face to about 12 inches from your computer monitor and listen to the sound you are making.
3. Now turn your head slowly to one side and listen as the sound changes. The sound will change due to the changing angle that it is hitting the monitor at, and once you have turned your head away from the monitor, it will change due to the distance of the objects that it is being reflected off of.

This exercise assumes that you have a fairly flat computer monitor that is directly in front of you and directly facing you, and that there are objects at significantly further distances (at least 18 inches) away from your face, on either side of it. Any flat object will work for this exercise. In the next exercise I will talk about using a flat piece of cardboard or plastic which would work just as well in the above exercise.

Beginner Lesson #3 - How to Tune your Senses for Echolocation - Exercise #1

Image via WikipediaIf I haven't already said this, echolocation is not an ability that you're born with; something you either have or don't have, it is a skill that can be learned. Any hearing person can learn it if they are willing.

Your hearing senses will need to be sensitized in order to start tuning into hearing the different subtleties related to echolocation. These include phase shift, reverb, stereo effects, equalization, panning and more. These are all subtleties that musicians train themselves to be aware of, and you can do the same with the intention of using them to improve your echolocation skills.

Sensitization Exercise #1: Listening intently to music

If you listen to a lot of music, this is a good way to begin sensitizing, however, start listening more intently. Try to pick out every different instrument in a particular song. Begin noticing subtleties such as:

1. Which speaker is each instrument coming from? Or is it coming from both? This is called "panning", and often times songs will "pan" one guitar further to the left speaker and another guitar further to the right. This is done to give the effect that the guitars are in two different places on a stage. Once you've started to pick up on this effect, you should be able to point directly to where each instrument appears to be coming from, which should be somewhere in between the two speakers depending on how much it is panned one way or the other.
2. Determine how "far away" each instrument (including vocals) appears. This is basically accomplished by the recording company by adding more or less echo to the signal. If a longer echo (or reverb) is added to an instrument it will give it the effect of being in a large room and possibly far away. If a short echo (or delay) is added, it will give the effect of having very nearby walls and will be closer and more intimate. Generally vocal tracks have more delay added so that the singer seems closer and more pronounced to the listener.
3. Compare songs. Listen to how different songs compare to each other and how different recording companies like to mix songs.

Doing all of the above will help you to get started in sensitizing your ears to echolocation. This first exercise is something you can do on your own, but exercise #2, you will probably need a partner for.

Go on to Exercise #2 -->>

Echolocation Using Clicking Devices

Image via WikipediaHandheld clickers may be used for echolocation, and I have had minimal experience with this, but I will dispel all I have learned so far. You can use a Snapple-type cap, or a pet training clicker. First thing's first, you must get used to the sound of the clicker. Play with it as much as you can, every day. Eventually you will be able to recognize it easily and at this point you will have learned many of the subtleties of the sound. Clickers should be sounded around the waste level or above the head, don't click them near the ears since this will defeat the purpose. The goal, as always with echolocation, is to create a triangle between the source, object and receiver. So in this case: clicker, wall, and ear.

I find it is also helpful to create a barrier directly between the clicking source and your ear. This could be your other hand (as if saying "Stop") a notebook, or even a bag you're carrying. This will prevent the signal from going directly to your ear and will isolate the reverberating signal (which is the important part)

When using a clicker, pause for about a second between the press and the release of the button. This will give the reverberations time to subside and will avoid confusion for your subconcious.

An interesting observation on clicking... or not clicking.

Image by vinduhl via FlickrI was echolocating through the hallway at work the other day, and I noticed a lot of high frequency noise which I think has been there all along, but I hadn't really paid attention to it. I think it was either coming from the deformation of the carpet fibers under my feet, or the stretching of the fabric in my shoes because it was synchronized with my gait. It wasn't necessarily just the sound of footsteps, because it seemed like it was always present, and just increased in volume at every step.

After listening to this sound for a while I realized that I was actually using it quite effectively to echolocate. Possibly more effectively than clicking. And I can see where the myth of "pressure on the face" comes from. Since this sound was more omnipresent than the sporatic clicking you get a much better transition between the "presence" of different objects.

This makes me wonder, if some white noise were to be emitted at, say, the belt buckle level (somewhere away from the ears, but a source that travels with you) if that would be of great benefit for echolocation. Maybe clicking is not the way to go?

Anyone out there ever notice this phenomenon? Let me know what you think.

Getting used to a new echolocation click

Image via WikipediaI'm working on getting used to the "Blade Pop" click. (See article on "Analysis of Different Clicks") I find it is a good idea to perform the click as you walk around. When you're clicking just listen to the sound of the click. If you are seeing, then feel free to keep your eyes open, if not then observe in the best possible way, the nearest object and listen to the sound and how the sound changes as you walk around and move from object to object or from room to room.

After doing this for a while you'll start to notice the slight differences in the sound, and you'll be able to make little tweaks in order to improve it. (See article: "Properties of a good Click") Even if you don't think you're noticing, you may very well be subconsciously learning, as a great deal of echolocation is achieved by subconscious recognition. You can change the frequency by changing the shape of your mouth, and if you continually make the sound you will just get accustomed to it, and gradually it will become easier to use it for echolocation.

Waveform analysis of Tongue Clicks for use with Echolocation

For this post, I have analyzed three of the more popular methods of clicking. Using a studio recording microphone (AKG Perception 200) I recorded myself clicking to the best of my ability. The three clicks in question here are:

The "Cluck": Made by lightly pressing the tip of the tongue against the roof of the mouth and then breaking the vacuum and smacking your tongue against the floor of your mouth.

The "Giddyup": This one is made by breaking the vacuum and drawing air in between the sides of the tongue and the molars, and is commonly used to communicate with horses. This signal, by nature, is produced at the sides of the mouth, and therefore is emitted away from the sides of the head. This is interesting in that we can send the signal to either one side or the other, but it is more difficult to send the signal directly to the front with this method.

The "Blade Pop": This one is the most difficult for me, but sounds like the one used by many proficient echolocators. This requires that you suck the blade of your tongue (the big meaty part in the middle) up against the roof of your mouth until you've got a good amount of surface-to-surface contact, and then break the vacuum by pulling your tongue away. This one requires significantly more vacuum than the previous two. When executed correctly, it sounds distinctly like a bottle cap being depressed or released.

The frequency of all three clicks described above can be adjusted slightly by the shape of the mouth. Generally a wide mouth or smile will generate a higher primary frequency, as well as make you appear happy :)

Signal Analysis

Below, I've uploaded the waveform generated by each of these clicks, as well as a spectrum analysis. The waveform shows the amplitude of the sound over a certain time period (as indicated), and the spectrum analysis is a plot that lines up with the waveform and shows the distribution of frequencies that occur within the sound signal. Brighter colors meaning higher concentration of waves in that region. Higher frequencies are at the top and lower frequencies at the bottom of the spectrum analysis.

The Cluck (200ms):


The cluck waveform is neat because you can distinctly see two spikes. The first small spike is the tip of the tongue separating from the roof of the mouth, and the second spike is the tongue smacking against the bottom of the mouth. Although the latter is significantly more prominent than the former these two sounds are within 10-15 ms of one another and have the potential to cause interference to the listener. This signal could introduce ambiguity.

The spectrum analysis shows that most frequencies coming from the cluck signal are quite low. The higher the frequency, the more energy it has and it also allows for better recognition and better resolution. (See Properties of a Good Echolocation Click) A broad distribution of frequencies would theoretically give you a reliable signal since some frequencies will be absorbed by objects and others will be reflected depending on the resonant frequency of the material or object.

The spec to the right of the actual signal is not an echo, but actually a drop of saliva swishing around in my mouth as an artifact of the signal creation.

This is the signal I started with, but have not had a lot of luck using it effectively. I think this is primarily because of the concentrated low frequency and "double pop".

The Blade Pop (100ms):

Notice the sound envelope as compared to the "Giddyup" below. The "attack" (time it take for the signal to get from zero to peak amplitude) is much less for this signal. Approx. 7ms for the Giddyup, as opposed to about 1ms for the Blade Pop. This gives the signal more of a distinct "pop" which will actually impact objects better and thus be reflected better. Think of it has a "harder" signal. A superball bounces better than a sponge. In other words, the object can be absorbative making it difficult to bounce a signal off of, but the signal can also be "squishy", making it easier for the object to dampen the impact as opposed to reflecting it.

Notice that there is fairly good distribution of the signal although there is a blank spot, and there could be more in the high end which would make for a better signal. If you look at the spot about 70% through the spectrogram, you'll see a faint echo of the higher frequencies. This is approximately 70ms from the generated signal and probably corresponds to the shape of the signal bounce pattern in the room. A 70ms delay would mean approximately 70 feet of signal travel, so this signal is more like an echo after the signal has bounced around the room a while as opposed to the instant ricochet off of the nearest wall.

This being the sound that I am struggling with, it may be that, with practice, I could distribute the signal over a wider range of frequencies and become more accustomed to its sound.

The Giddyup (300ms):

The signal itself has a 7ms attack as discussed above, and the signal itself is about 25ms as opposed to 12ms for the Blade Pop.

Good distribution of the signal, a little ricochet at about 70ms on the higher frequencies. As mentioned above, this one is directed away from the sides of the face, which may or may not be a good thing. It's nice that it is more inline with the ears, but then you have to turn your head slightly in order to notice objects directly in front of you.

This is the signal that currently gives me the most accuracy. I am accurate within 1/2 inch or so of flat walls whereas the Blade Pop only gives me accuracy down to 6 inches or a foot. I will need to play with that signal a bit more and report back, because I do like the distiction of it. It is much more "poppy" than the Giddyup.


I will need a more sound proof room and more controlled environment in order to directly observe the reflexive properties of certain objects with these clicks. It's a good thing the human brain is faster, smarter and more acute than any computer, otherwise we'd still need our eyeballs to see things.

Properties of a good Echolocation Click Signal

If I try out different clicks and postulate which click I think works best that would be extremely subjective and I’m sure that different clicks work better for different practitioners. However, there are many fundamental qualities of a click signal that make the signal better suited for echolocation:

Signal Frequency. The frequency of a signal governs the resolution, in that a shorter wavelength (higher frequency) will give you more definition as to what it has bounced off of. Low frequency waves, since they have a longer wavelength are not as distinct. It has been said that the region of 3kHz is a good place to be for echolocating.

It is my hypothesis that a broad distribution of frequencies would be desirable (above a certain value) so that if some frequencies are absorbed by an object, others will be reflected by it.

Signal volume. The sound must be loud enough to stand out over ambient noise. 40 dB is about the level of quiet speech from a few feet away.

Clarity. This is probably one of the most, if not the most important property of the sound. It is critical that after the sound is made, there are no artifacts of the signal source still emitting sound. In other words, the sound must stop abruptly so that the reverberations can be clearly heard. If the sound were to taper off at all, this small amount of sound would easily cover up the reverberations, or at least create a confusing blend of signals.

Directional. If the signal is omni-directional, IE, if it is the same volume in all directions from the source, it will be difficult to know the direction from which it is being reflected, and thus where the object is that is doing the reflecting. Think of it like a flashlight. You can point a flashlight at one object and see what it is. Whereas, if you switch on a light bulb you are able to see everything in the room and there is more information to take in. When echolocating, we want to eliminate as much excess information as possible.

Passive Echolocation Signals

Passive signaling during echolocation involves listening to the ambient noises in the room and interpreting them. It has it's pros, such as not being intrusive or noticeable, but it is not the best method for accurate echolocation. These sounds can be:

• People talking
• A running fan
  
• Footsteps
• Clothes rubbing against each other
• Hands rubbing together
• Breathing
• or other omni-directional sound sources.

One of the downfalls of these sounds is the fact that their source is undefined, and therefore any sound that is reflected to the listener has the potential to be bouncing from any direction and can not easily be used to identify the shape of objects.

These sounds can however be used to make broad observations such as the size of a room or proximity to a flat wall. Other estimations may be possible depending on the actual content, level and clarity of the sound and any other distracting sounds that also exist, noticeable or unnoticeable.

Echolocation in Terms of "Reverb"

Image by Northeast Indiana via FlickrLet's look for a second, at echolocation as it would be viewed by a musician. Every different room, every environment, indoor, outdoor or otherwise has it's own acoustical properties. These would be known to musicians as that room's reverberant properties, or it's "reverb". Certain rooms are said to have a certain type of reverb. Rooms with hard flat parallel walls generally have what is considered to be "a lot" of reverb, where rooms with softer (more absorbant) walls that are oddly mishapen are said to have less reverb, meaning that the sound is not as likely to bounce around as much. A highly reverberant room is labelled such because the sound waves are likely to bounce off of the walls, sometimes several times before making their way to the listener. This gives the effect that one short tone is stretched out over a longer period of time. Essentially, the reverb is made up of many very quick echoes from nearby structures.

You have undoubtedly experienced and are familiar with certain reverb characteristics. For example, if you are in a quiet environment and you close your eyes and snap your fingers, you will immediately be able to tell if you are in a bathroom, car or auditorium. If you thought about it a little longer you could probably guess if the floor was carpeted and what the walls were made of.

Since the exact shape of any room give it it's reverb, this is essentially the same thing as echolocation. Save for one small detail, movement of the source and reciever (sound source and your ears). A room can have reverberant qualities and you may be able to make generic assumptions about the make-up of the room by listening to a sound, but without moving the source and reciever you would be hard pressed to tell the shape of the room or identify any objects in it.

Once we move, we gain another dimension of information. The "echoes" which are making up the reverb we are listening to as we click to echolocate, are changing direction as we move our head. It is not one click that gives us the information we require, but rather the difference between one click and the next which tells us how objects are moving with respect to us, and therefore how we are moving with respect to these objects.

If you have watched people echolocate, you will notice that they move their heads from side to side, tilt their ears and walk around objects in order to distinguish what they are. They are taking the information differential between clicks and piecing it together like pieces of a puzzle. It may take several clicks before someone is comfortable in their surroundings or can identify an object. I would think it to be nearly impossible to gather much environmental information with just one click no matter how good versed you are in echolocation.

Beginner Lesson #2 - The Basics of Echolocation - How to Know What to Listen For

Image via WikipediaIf you've never tried to echolocate before and don't really know what it is, then read this article, it will give you an idea of what to listen for.

One of the first times I noticed the effects of echolocation, I was sitting at my desk at work, and listening to the radio. The speakers were biased to one side of my head, and I raised a hand up on the opposite side of my head - maybe one foot away - and found that the sound reflected off my hand and into the ear that was getting less music. Try this, and now move your hand around a listen for the sound reflections. If it's not obvious enough with just your hand, try a folder or binder (something larger, flatter, and more rigid will be a better reflector). The image above illustrates why flatter surfaces make better reflectors. Sound reflects off of objects similar to the way light does.

Now try twisting your hand or binder back and forth, but keeping it in one place so that you're reflecting the sound away from your ear, and then directly at your ear, and then away in the other direction. It should appear as if the sound source is passing by, while really, it is just the shape of the reflecting object creating different effects.

The effects you will hear from this exercise are quite a bit more pronounced than the effects you will see when you start using clicking to echolocate, but this should give you a good idea of what kind of effects can be observed when sound reflects directly off of a small object.

Echolocating Through a Doorway

Image via Wikipedia

To get a feel for echolocating you can try this quick exercise in an inside doorway.

1. Stand 3-4 feet in front of a doorway. If possible the door should be positioned in a flat wall and it should be fairly clear of obstructions on either side. Make sure there are not too many distracting noises surrounding you, it’s certainly easier if it’s a very quiet environment. Oh yeah, it’s also important that the doorway does not have a threshold, this will be a dead give-away later on.
2. Close your eyes and listen. Take notice of any ambient noise around you. Notice how these ambient noises change as you turn your head. Address the doorway and make the clicking noise of your choosing. Turn your head back and forth to click in the direction of both sides of the doorway. Step forward toward the doorway and observe the changes.
3. Finding the door. Step all the way through the door and notice the changes in sounds from one room to the next. Try to hear when you are exactly inside the door jam. Try to hear if you are closer to one side than the other, remember to keep turning your head. Focus on one ear at a time, what are the differences? If you think you’ve made it, open your eyes or grab onto the door jam to see how you’ve done. If you’d like you could try turning 90 degrees and approaching one of the sides of the door jam and see how close you can get your nose to it without touching it. While clicking, make your estimate before you verify your success.

Intermediate Echolocation Lesson #1 - Walking a Predetermined Path

I was visiting a friend down the road last night, and on my way home it was fairly dark and there were not a lot of people roaming around my little suburban-type town, so I was able to get in some good echolocation practice. My trip was about 1/2 mile and it is a fairly straight shot on a somewhat even sidewalk. I am still very much a beginner at this so if you already echolocate, this will probably not be news to you, I can only offer my observations of myself as I'm learning.

This was my method that seemed to be fairly fruitful:

1. Sighting your target. With your eyes open, look ahead, down the path that you are to travel. I find that somewhere between 30 and 60 feet is a good starting distance. Pick a distance that is long enough so that you will not be able to count your footsteps, but short enough that you will not get discouraged or lose track. Pick a landmark at the end of the path; a telephone pole or bush that you can end at. Familiarize yourself with the lay of the land so that you will have a starting point and some familiarity. Notice changes in terrain, bushes, parked cars, telephone poles, fire hydrants, etc. If you are blind then you'll most likely be attempting to navigate a path that you have previously used a cane for, and are familiar with the obstacles that you must avoid.
2. Setting your course. Once you know approximately where you're trying to get and what obstacles you need to avoid, it's time to set you course. Which side of the tree will you walk on? Will the fire hydrant by to your left or your right? Will you need to adjust your direction to navigate around obstacles? By doing this you will be able to break up your echolocation journey into smaller segments. (IE, after the firehydrant, vear right to avoid the overhanging bush.
3. Closing your eyes. Close your eyes. If you are blind this mean stowing your cane. You will probably be tempted to peek... it is natural, but don't, it kinda defeats the purpose..
4. Echolocating. Now to begin the echolocation journey. The first few steps you will be expecting. The immediate terrain and obstacles will be in your short term memory and you will easily navigate them without clicking. But click anyway so that you can hear and get familiar with the echoes. As you approach your first large object, maybe a car, tree or telephone pole, be aware that it is there. Listen for it and concentrate on the echoes. Obviously, the point here is not to touch anything that would give away the path, but if you are nervous about smacking your face into anything you can keep your hands up. I would suggest keeping them low and out of the path of your clicks, however.Objects that are nearer to your starting point will be easier to pinpoint. Click in the direction that you are expecting to find an object. Once you have reached a landmark, acknowledge it, try to judge it's distance, and then visualize your path with relation to it. What is the next landmark? The car on the left? Focus on the path and continue down it with a strong concentration and expectation of hearing the reverberation off the car. Once you get to it, acknowledge it. Notice the differences between the car and the telephone pole. The telephone pole, since it is round will sound the same from any direction. The car will change its reflective properties as your angle to it changes. I find that cars and metallic objects also reflect higher frequencies due to their less absorbent characteristics.
5. Reaching your goal. Once you have navigated yourself through you predetermined path, you should be at your end landmark. Be sure to stop when you have gotten to the landmark and acknowledge it. If possible, walk around the object still echolocating and clicking towards it. Remember not to touch it! Are you sure this is the correct object? Or is that thing you think is a telephone pole actually a bush? How far away from it are you?
6. Open your eyes. Take out your cane. Confirm the object that you've approached. Is there even anything there? How close did you come? Keep clicking for a little bit to understand what you are hearing. Where you hearing another echo from a nearby tree that threw you off? Did you judge the distance accurately?

Now wasn't that fun? As I'm typing it, it got a bit more involved, and I will certainly be typing up more exercises that might be easier, and as I progress, getting a little harder. Good luck with this one and don't get discouraged if you're not getting it. Just try objects that are a little closer or larger.

The Profundity of Echolocation and the Human Race

Image via Wikipedia
Echolocation is a physical ability that we possess and has been proven by many blind people. Its primary function is currently with the blind population, and while the blind are said to have more acute hearing, it has been tested (even amongst the best echolocators) to be no "better" than the average person. They have simply been given the opportunity to put more focus on it and thus have become more in tune with its subtleties.

Hundreds of thousands of years of human development are to be attributed to the fact that we use tools, brains, and all of the physical abilities at our disposal. Echolocation is an ability that has gone unacknowledged for many thousands of these years. Certainly there have been people to use it, most likely blind, (the case of James Holman stands out as notable amongst many blind people who claimed to be able to see objects via "pressure" on their face, or "facial pressure") but it has not been brought to the attention of the mainstream public until very recently.

Imagine that the human race had never realized that it was possible to hurtle one's body through the air, curl it up into a ball, flip around and land on one's feet. The first time someone successfully landed a front tuck was a revolutionary turning point in one small area of human development. Gymnastics is an incredible ability that is not necessarily feasible for everyone, but the human race has worked hard to develop it into a sport and a form of entertainment. People teach it and practice it because it is challenging and enjoyable.

This is much like echolocation. If your parents had told you that you could hear the sound reflected off of objects, and told you "Listen to where the tree is" just like they told you "Look at what color the ball is" then you probably would have grown up with at least an acknowledgment of the existence of this ability. It is human nature for people to explore their own abilities and therefore you probably would have practiced or at least noticed this sense in your development. Now, what if people had been developing this ability for the past 10,000 years, just like the abilities of speech, walking or running. Imagine where we would be. The world of darkness and blindness would be so much less foreign to us and there would be many opportunities and abilities which inherently implement echolocation that would easily become apparent should we refine this ability.

As Eric Schwitzgebel stated in his blog Echolocation and Knowledge:

...most of us, even if not wrong in quite that way, are strikingly ignorant about this aspect of our stream of experience.

We have so much room for development in the area of echolocation, and so much to learn. I'm glad that we have not reached the final plateau in learning about ourselves (although I know that would be an outright impossibility).

Working on the best Click for Echolocating

The sound emitted during echolocation is critical since it is the direct properties of the reverberations of that sound that you'll be analyzing. This means:

1. It's got to be a sound you are familiar with. You know the sound of you front door and you know the sound of a soda or beer can being cracked open. Sounds like these are powerful in that they instinctively trigger thoughts and emotions prior to you actively conceptualizing their source. The sound you use for echolocating should be similar to this so that you are familiar enough with it to recognize the very subtle variations that are necessary for echolocation.
2. It's got to be consistent. Whatever it is try not to change it up to often unless you experimenting. One sound may return different reverberant characteristics than another in the same environment.
3. You've got to be able to hear it. It doesn't make a lot of sense to make a sound that will be difficult to hear, which implies that the sound wave must have enough energy to return to your ear, and still be recognizable. Higher frequencies have a higher energy than lower frequencies and therefore will return better. They will also give you better resolution since the wavlength is shorter.

Here are a few of the different tones I've been experimenting with:

1. Car engine. This is used when driving with the passenger's side window open and echolocating passing objects. Read echolocating while driving in the car, for more, but you've got a great tone for a lot of reasons:
   
   • There are many different frequencies present.
   • It is consistent.
   • It is loud. I have been able to echolocate and determine the shape and material of objects up to about 50 feet away from the car.
   • It is not directly heard inside the car. Meaning most of the sound is outside the car and can be reflected inward making the reflected sound the dominant one as opposed to the source.
2. Footsteps. These are okay to use since they are generally distinct and high frequency, but I find that they are very inconsistent depending on the terrain and what kind of shoes you are wearing.
3. Scuffing of pant legs. Fairly consistent, but usually just not loud enough.
4. "Cluk" - The sound of the tongue smacking the bottom of the mouth as if to make a "clop" or "pop" sound. As far as I can tell this is what most practicing blind people do including Ben Underwood. It gives a nice quick defined tone that is fairly high pitched. And since the mouth is closer to the ears than say, the feet, the reverb characteristics, I would think, are more accurate.
5. "Kik" - This is a sound made on the sides of the tongue as if you were guiding a horse. It is made by sealing the tongue against the roof of the mouth and creating a negative pressure inside your mouth and then releasing your tongue's seal. It will result in a "kik". I've taken a liking to this one for a few reasons:
   
   • It's even higher pitched than the "cluk".
   • It's easier for me to make, therefore I can make it louder.
   • It emanates from the sides of the mouth rather than the front thus reflecting more of the tone directly back into the ears.

So I'm going to keep using the "Kik" method and we'll see how that goes. Another thing I wanted to try was snapping with my fingers somewhere under my chin. I will try this and report back if it is any good. The reason I say under the chin, is so that the sound source is close to my ears, but the direct signal is somewhat blocked by the underside of my face leaving me with a better perception of the sound as reflected back.

Echolocation vs. "Facial Hearing"

Image 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.

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.

Hallways

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.

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.

Mailboxes

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.

Fencing

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!

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.