Hand-Mounted Sonar For the Blind

GeekTech.in writes "The Tacit, a wrist-mounted sonar device with haptic feedback, is like strapping a bat to your wrist to help you see. It makes use of two sonar ping sensors to measure the distance to the nearest obstacle. The relative distance to an object is then fed back to the user using two servos which apply pressure to the back of the wrist."

Comments

Bad news, good news

[ozmanjusri]

Well, the bad news is that it's an incredibly ugly watch.

The good news is that it's users will never know.

Re:Bad news, good news

[Maritz]

Humans didn't evolve in the jungle.

Worst description ever

[Anonymous Coward]

"Like strapping a bat to your wrist to help you see." Somehow that doesn't instill me with confidence in relation to using this product. That sounds like the stupidest idea I've ever heard. Not only do I not see it helping the blind to navigate, but it also sounds like it's extremely unwise :)

Re:Worst description ever

[Lysander7]

You've obviously never heard of Ben Underwood (http://en.wikipedia.org/wiki/Ben_Underwood#Ben_Underwood), whom is often listed among the top ten contemporary inspirational people. Not only was he able to "see" using echolocation via clicking noises with his tongue, he excelled at tasks such as mountain biking. And he is not the last blind person able to do so.

Re:Worst description ever

[narcc]

That kid is amazing. Not only can he ride a bike around like any sighted kid, he can also play basket ball incredibly well.

I recommend anyone unfamiliar go dig up some videos of this kid in action.

Re:Worst description ever

[jhoegl]

Yeah, a portion of blind can see via clicking. I watched a documentary on this and the pitfalls of it. Apparently clicking can only let you see on a "2d plane", clicks are only reflective off of objects within your horizon. Meaning that you will not know about sudden drop offs until you fall into them.
So, because clicking is basically sonar, I am thinking this device has the same fault.

Re:Worst description ever

[arose]

You've obviously never strapped a wild animal onto your wrist.

Re:Worst description ever

[Nyeerrmm]

I would venture that the 2d limitations of natural human sonar have more to do with the fact that our ears are in a horizontal plane and thus can't distinguish up/down variations. Except in special circumstances, the air through which the sound is travelling is not going to be stratified enough to make a difference.

Given that, this is likely to sidestep that limitation, since it appears far more directional, and mounted on a hand, which is more natural to tilt than ones head.

Re:Worst description ever

[iluvcapra]

This isn't true, your brain is able to locate the azimuth of a source using spectral differences imparted by the pinna and diffraction artifacts caused by your head and body. This is why HRTF headphones allow you to hear things "over" you and why IMAX and 10.2 speaker systems have speakers above the screen, and not just behind it.

Re:Worst description ever

[Nyeerrmm]

Are you saying that the diffraction effects allow one to determine source altitude? Azimuth I would imagine is easily distinguishable from using the ears as mere point sensors, as I mentioned in a sibling post.

Very interesting. (not saying that sarcastically).

Re:Worst description ever

[jhoegl]

I am not going to pretend to know how they see or perceive things around them, but I saw it in the documentary. They went to a small drop off, probably 10 feet, natural in that there was no concrete, and they asked the blind guy if he "saw" it through his clicking. He did not. The reason they were testing him was because they wanted him to carry a cane, something he felt would create empathy for him, something he didnt want.

Anyways, it is true in the case of the blind.

Re:Worst description ever

[Anonymous Coward]

Isn't one ear slightly higher than the other for this reason? Or am I thinking of owls?

By the same logic we shouldn't be able to distinguish between things directly ahead or directly behind. I think it's to do with how the shape of the ear affects the frequencies of different sounds, innit?

Re:Worst description ever

[vlm]

You've obviously never strapped a wild animal onto your wrist.

Falconry? At least for outdoor work I'm surprised to have never heard of any avian service animals. Its always "seeing eye dogs" never "seeing eye falcons"

http://en.wikipedia.org/wiki/Falconry

Re:Worst description ever

[jellomizer]

Yes, I saw that documentary too. While his skills were really good, the point was he still needed a cane (although it didn't want to use it, because it would show people that he was blind) Also if you have fast moving objects it could effect your view of the world a fast moving car between clicks can go from well out of your range to about to hit you.

This skill is a great enhancement to using a cane. However not a full replacement for other services out there, and (at the risk of not being politically correct) the blind person isn't fully aware of what is going on and will need help from others to survive.

Re:Worst description ever

[turtledawn]

Most birds are amazingly stupid and (forgive the pun) flighty. You could, possibly, train a crow or raven to be a useful service animal, but even they lack the degree of control over their defecatory functions that we expect service animals to display.

Re:Worst description ever

[Sulphur]

Isn't one ear slightly higher than the other for this reason? Or am I thinking of owls?

By the same logic we shouldn't be able to distinguish between things directly ahead or directly behind. I think it's to do with how the shape of the ear affects the frequencies of different sounds, innit?

Is that why some heads get tilted? I am not thinking of owls.

Re:Worst description ever

[Sulphur]

Most birds are amazingly stupid and (forgive the pun) flighty. You could, possibly, train a crow or raven to be a useful service animal, but even they lack the degree of control over their defecatory functions that we expect service animals to display.

Use a tray. If that is too hard, wear white.

Re:Worst description ever

[arose]

More tethered than strapped, not for long, mostly on the forearm and certainly not wild. There's also a thick leather glove involved, so falconry would involve tethering a trained animal to a glove covering the hand and forearm.

Good effort nonetheless, I didn't think of that.

Hot point which summary doesn't mention..

[intellitech]

And it should've, damnit.

Keep reading for more information, build notes, parts list, schematics, and code. ...

Important Note #2: The circuit and software is released under a Creative Commons BY-NC-SA license, which I think of as a "Don't be a jerk" license. In short: Make it, learn from it, teach it, improve it, modify it. Just share what you do, give credit, and don't sell any without contacting me first.

PARTS LIST?!? CIRCUIT INFO?!? WOOOT! Now this looks like a damn fun toy.

Re:Hot point which summary doesn't mention..

[siddesu]

I did something similar for my blind dog, which it used for a year before it died earlier this year. I a circuit like this one as starting point: http://www.kerrywong.com/2011/01/22/a-sensitive-diy-ultrasonic-range-sensor, and a cheap vibration motor like this one: https://www.dealextreme.com/p/repair-parts-vibration-motor-for-iphone-4-73348, but you can use a parallax PING module or something similar.

Basically, a controller (I used an atmega chip with an arduino bootloader) that sends pings and moves the motors stronger as the obstacle is closer. Mounted it on the head of the dog, and had the two vibration motors on two sides of the chest. The dog had it figured out in less than a day.

The only "hard" part is that if you go DIY all the way, you'll need an oscilloscope to build the ultrasonic sensor thing, otherwise it is rather simple.

Re:Hot point which summary doesn't mention..

[siddesu]

I a circuit like this one

Doh ... I ACCIDENTALY a circuit like this one. The whole thing. Used, I mean.

Re:Hot point which summary doesn't mention..

[Anonymous Coward]

This is slashdot.

Normal users will skip over it, understanding exactly what you meant to say.

Grammer nazis will probably call you out on it, even if you call a safety.

And, robots, well, they'll likely panic when confronted with a missing verb.

Re:Hot point which summary doesn't mention..

[bronney]

Dude your correction made it worst now I am so confused :D I can't divide by zero!!!1

Re:Hot point which summary doesn't mention..

[anilg]

Interesting. Did you blog about this by any chance? Pics of it on the dog. I would've thought dogs wouldn't learn a whole new sense.. but they seem to corellate sensor input and the world well enough, according to what you say. I'd be interested in learning more about this..

Re:Hot point which summary doesn't mention..

[mla_anderson]

Can't speak to this device since it looks a lot more complex, but I did a similar project in school for my EE. It ended up pretty simple after considering more complex options. The device had an ultrasonic emitter, an ultrasonic receiver, a 555 timer and a speaker. The 555 drove the emitter and speaker at a given frequency of chirps. However if the receiver got the pulse early it would interrupt the 555 and cause it to transmit sooner. Thus as an object got near the frequency of chirps would go up.

Parts List: (from 15 years memory sorry)

• Ultrasonic transmitter
• Ultrasonic receiver
• Speaker (aka sonic transmitter)
• 555 Timer + R/C timing parts.
• Amplifier (transistor I think) for both the speaker and transmitter
• 9-Volt battery

This device was mounted to a pair of glasses so the user would just move their head around to scan for objects. It could catch the edge of a table, but obviously had trouble with surfaces at a significant angle. One problem during testing was the transmitter would over power the receiver when it wasn't on a user's head. Instead of keeping a handy supply of freshman heads around I tried a 2x4 and found that ultrasonically at least the human head and a 2x4 are very similar.

Random junk because slashdot doesn't think I'm human...however I know my head and a 2x4 look the same to ultrasonic which must prove I am human.

Re:Hot point which summary doesn't mention..

[Anonymous Coward]

You strapped something that makes noise at 24 kHz to a dog's head?

The poor thing...

Re:Hot point which summary doesn't mention..

[siddesu]

No, I don't blog and I do not distribute videos, most of them are too ... unsuitable for distribution. If you want schematics, etc. we can work something out. It wasn't rocket science thing, really, just two buzzers on the pwm outputs and some electronics to measure distance and direction. And it wasn't a "new sense", ever since the dog got deaf and nearly blind it relied mostly on smell and touch to get around anyway.

Re:Hot point which summary doesn't mention..

[siddesu]

Dogs tend go deaf when they get old. Mine went completely deaf at 14, about 5 years ago.

Re:Hot point which summary doesn't mention..

[Anonymous Coward]

if it isn't too much: could you elaborate, how are the "unsuitable for distribution" ?

Re:Hot point which summary doesn't mention..

[siddesu]

Childish or not, I am still too sad about the dog dying, and I am not really comfortable watching, editing, uploading stuff about it.

Basically an electronic cane..

[pimpsoftcom]

... Except its batteries can run out when the person is in the middle of a busy highway.

Re:Basically an electronic cane..

[Anonymous Coward]

How would a cane help in the middle of a busy highway?

Re:Basically an electronic cane..

[scottbomb]

Yeah, I sure wish those blind people would stay off the highway. They're enough of a road hazard already!

Oh, you mean crossing a street? I guess they'd just do it the old-fashioned way in that case.

Re:Basically an electronic cane..

[Anonymous Coward]

You can hide your cigars in it if the nurse doesn't let you smoke.

Re:Basically an electronic cane..

[AwesomeMcgee]

"old-fashioned way"? Crawling?

Batty acronyms

[AthanasiusKircher]

From the summary (a suggestion that sounds improbable and unadvised):

...like strapping a bat to your wrist to help you see...

From TFA:

This is a project I'm calling Tacit. No, I didn't bother making an awkward backronym for it....

I think he's not telling us everything. I'll bet the T in TACIT stands for pteropine... it's just that the 'p' is tacit......

Re:Batty acronyms

[phantomfive]

I'll bet the T in TACIT stands for pteropine... it's just that the 'p' is tacit......

lol that is hilarious.

Re:Batty acronyms

[msheekhah]

I was thinking about composing a song Tacit in D Minor...

Re:Batty acronyms

[Have Brain Will Rent]

It's more likely the he was tipping his hat to "The Tacit Dimension" by Polanyi - a very dense book to read. See:

http://en.wikipedia.org/wiki/Michael_Polanyi

Re:Batty acronyms

[AthanasiusKircher]

It's more likely the he was tipping his hat to "The Tacit Dimension" by Polanyi - a very dense book to read.

Polanyi's writing is pretty easy going -- not to mention reasonable -- as philosophy goes, IMO (try Kant or Hegel sometime).

Regardless, I think it's more likely he's just making a reference to the basic meaning of "tacit," i.e., silent... like sonar.

Viral

[Anonymous Coward]

We should miniaturize these and put them on cats' feet. The ensuing video would be an instant meme.

When will you learn

[Anonymous Coward]

VIDEOS can not be seen by BLIND PEOPLE. Why don't you learn a few words and present it that way, then the actual target of the device might actually find out about it.

Yes, I'm an anonymous coward, because I don't feel like sharing my personal information with idiots.

Re:When will you learn

[Anonymous Coward]

Yo don hav t shar yo ar bi asshol lik goatsec gu

Re:When will you learn

[_4rp4n3t]

I came across an interesting advert targeted at the deaf community today - on the radio.

Re:When will you learn

[turtledawn]

Well, I present a radio show for the blind and disabled, so at least some of the targets will be hearing about it next week. Meh.

http://www.uky.edu/Libraries/ckre/
http://tunein.com/radio/CKRE-s69088/

Re:Golden Girls!

[Anonymous Coward]

you're a pal and a cosmonaut.

Confidant. The word you're looking for is confidant.

human echolocation

[phantomfive]

Blind humans can do a better job of echolocation just with there ears. Check it out (An amazing more complete version, but it's long).

There's even a school that helps teach echolocation to blind people, based in California, I believe. Wikipedia has a basic writeup on it.

Seriously it's pretty amazing to think that a human can develop echolocation ability. But we can.

Re:human echolocation

[Anonymous Coward]

Not all blind people can echolocate with their ears. I'm registered blind (though I can still see) but I'm also hard of hearing. Some people with hearing problems can learn to echolocate but a lot can't, I personally found that my hearing-aids don't allow for enough subtlety? to get very far with it. Incidentally, I met Dan Kish and Brian Bushway at a seminar and their echolocation feats on stage were impressive, however, I also saw them arriving and leaving and at those times they were simply being guided by their carers and using their canes. Perhaps it's too tiring to do it all the time, or maybe film editing make it look a lot more impressive than it really is, but I came away with the impression that it can be a useful tool but it isn't a general solution. An electronic device seems to me to have more potential, it doesn't get tired, it works for those of us with poor hearing and it doesn't have to be stuck at head level - I know that I'd like them to be at knee/shoe level because that's where I get hurt most.

Re:human echolocation

[Weedhopper]

For two separate, month long periods about a year apart, I spent 30-45 minutes a day practicing echolocation.

Do NOT start practicing in a carpeted room/house.
DO start in a room with relatively hard surfaces first.
DO start with your hands cupping your ears. The hardest part of this will be getting the consistency of your hand cups, but you'll come to recognize the tone of the rushing blood in your ears for consistent positioning.

I never got very good, but did get to a point where in a dark room, I can get an idea of the general shape and size of the large, hard objects (tables, chairs, shelves, etc). I have a harder time telling where soft objects are, particularly in carpeted rooms. For example, my "echolocation sense" doesn't work very well in typical hotel rooms.

Re:human echolocation

[phantomfive]

Sweet! I love hearing this kind of story! I was wondering what it would take for a non-blind person to get the hang of this. How long did it take before you started to get anything?

Hack a day covered this a couple days ago...

[Anonymous Coward]

http://hackaday.com/2011/08/19/the-hand-mounted-haptic-feedback-sonar-obstacle-avoidance-asstance-device-or-the-tacit/

For one, not every blind human can handle that.

[intellitech]

The augmented sensitivity of hearing doesn't immediately happen when you go blind, it's something that improves over time, as an individual's senses are forced to compensate. I can see this being very useful for somebody who just lost their sight, or a blind individual who doesn't feel like attending a class.

It's another option on the table, and that's exactly what I believe it was intended to be.

Re:For one, not every blind human can handle that.

[phantomfive]

Are you one of those people who, when they find something new, cannot resist the urge to say why it is wrong? 'Blind people who don't feel like attending a class?' What?

Re:For one, not every blind human can handle that.

[Anonymous Coward]

Are you one of those people who think they are the only ones to know of fairly well known things? It hasn't eliminated canes yet, so no it just might not be for everyone.

Re:For one, not every blind human can handle that.

[DJHeRobotExVV]

Are you one of those people who, when they find something new, cannot resist the urge to say why it is wrong? 'Blind people who don't feel like attending a class?' What?

Troll. You dropped a textual deuce all over the device listed in the article, then when someone pointed out more than one use case in which the device listed in the article could be useful, suddenly the other person is the one who "cannot resist the urge to say why it is wrong". Piss off.

Re:For one, not every blind human can handle that.

[phantomfive]

Oh yeah? How big exactly is the set of people who are blind, don't like to go to classes, and want to learn how to use a hand sonar? You may call me a troll, but you aren't thinking clearly.

Re:For one, not every blind human can handle that.

[phantomfive]

Good point.

Re:For one, not every blind human can handle that.

[Anonymous Coward]

I also know someone who is both blind and deaf, for whom finally getting a working cochlear implant was a triumph of my very, very stubborn engineering. (The normal design couldn't give enough voltage and current for their very damaged inner ears: I rebuilt that thing 3 times, using a lot of my own time and investing my own money in some of the custom designed components.)

Giving that person or people like tiem some additional awareness of their surroundings could be very valuable.

Re:For one, not every blind human can handle that.

[Antique Geekmeister]

All of the blind people who use public restrooms, perhaps? Have you ever tried to find the toilet paper in a public restroom when the bulb has failed, or when the light switch is difficult to find?

Re:For one, not every blind human can handle that.

[DJHeRobotExVV]

Oh, goodie, another idiotic troll to pick apart! Hey, Captain Asperger's, did it occur to you that maybe the guy to whom you were replying mis-used the term "don't feel like going to classes" for the more understandable "lack the time or money to be able to go to a class"? I'm curious, are you volunteering to pay all the legally-blind people in the world with day jobs and busy schedules to attend the class? If not, shut the fuck up, you pathetic trolling piece of shit.

Re:For one, not every blind human can handle that.

[Riceballsan]

I would have to assume a very large percentage of blind people are on disability. Someone who has just turned blind almost certainly is on disability (Not many people have jobs that can be done blind these days, can you name 3 jobs that don't involve navigating thin hallways, operating a computer (obviously not your computer so it hasn't been specially adapted for the blind), handling money etc.... Secondly money and experience, I'm sure the basics of the hand sonar will not take long, but actually using it efficiently for many tasks isn't necessarily going to be easy or an instant gain of knowledge, nor is the device itself going to be cheap or free. Not to say this idea doesn't have advantages, particularly if their isn't a location for the echolocation schools nearby and so on. Both methods have advantages and disadvantages.

Re:For one, not every blind human can handle that.

[phantomfive]

Have you ever tried to find the toilet paper in a public restroom when the bulb has failed, or when the light switch is difficult to find?

No actually, have you? Because it doesn't sound that hard.....it sounds like all you have to do is reach around touching the walls until you find it. I mean, I'm sure finding toilet paper is a thing that might be helpful for blind people, but are you sure this device would help very much with that task?

Re:For one, not every blind human can handle that.

[Anonymous Coward]

Haha you really want to reach around in a rest room until you find the toilet paper? Personally, no thanks.

And yes there are people who wont want to go to class, just like there are people who deal with a major teams (rape, death of someone, etc) that don't want to go to support groups, meetings, counsoling, etc.

And like the poster above posted, while the device may work great, the natural ability to do the locating comes with time as your hearing compensates for the loss of vision. But you'll still have people who wont want to use the device, just as Tue person mention way up in the comments didn't want a cane because he felt it would bring potty.

Re:For one, not every blind human can handle that.

[Anonymous Coward]

Haha you really want to reach around in a rest room until you find the toilet paper? Personally, no thanks.

Any true geek always has a torch (flashlight, if you prefer) with them. I used to have a pocket LED torch on my keys, now my phone does a good enough job. Of course, a large percentage of geeks wouldn't use a public restroom in the first place :)

Cool, but it could be cooler

[93 Escort Wagon]

I think they really should have included that old submarine sonar ping.

Also, having watched the video... that's not going to work very well in a crowded room - the blind guy could be hit with a lot of sexual harassment complaints. It might make more sense built into some sort of headgear.

Re:Cool, but it could be cooler

[cavePrisoner]

It was originally mounted on headgear, but presented problems. Aside from looking goofy, a version based around the head misses most obstacles, since they are generally near the ground.

definition of

[Anonymous Coward]

flamebait?

Re:Golden Girls!

[Xaositecte]

I like his version better.

dual use

[Black Parrot]

And when someone hassles you too much, you just set it on 'stun' and give them a blast with it.

Re:dual use

[Yamioni]

The version I saw deals 1d4 sonic damage.

Good idea...

[frosty_tsm]

But if it's only sound-based, it's doomed to fail.

Back in college (which wasn't exactly eons ago) I was programming robots to maneuver spaces using 1) a camera and 2) sonar and 3) infrared. As cool as sonar was, it had two major drawbacks. First, it could only check distance about once a second (partly due to the fact that there were 12 of them, but you get the idea). Second, the sound was very prone to being absorbed (fabric on a cube wall) or dispersed (angles). This resulted in some amusing thumps as the bot would get a no-response from the cube wall, think that it was wide open, turn to it, and floor it.

Add some EM sensors and then you'll have something that makes the life of a blind man easier.

wow, what insight...

[mevets]

I always wondered why I looked to the horizon when I heard what I thought was an aeroplane....

Have you ever actually stepped outside? The variation in sound is amazing once you step away from that techno-crap....

Re:wow, what insight...

[Nyeerrmm]

Easily justified by the presence of a priori information. You know what an airplane sounds like and that unless you're at an airport, one would hope that it's in the air.

Simply put, humans are incredible sensor platforms, able to synthesize information from both simple and complex sources. Nonetheless, your ears are essentially two point sensors, so while you can distinguish quite a bit by hearing alone, azimuth by differencing the volume to each ear (of course there's a front-to-back ambiguity), distance by expected volume, and change in distance by Doppler shifts, you're still limited by basic physics. Of course if you're needing to distinguish up and down locations by sound alone, you can always cock your head and get quite a bit more that way.

Of course, I'm no expert in biology -- I'm more interested in sensor systems, thus my tendency to analyze human senses in those terms.

Re:wow, what insight...

[bronney]

Dude you ever lived in an apartment sandwiched by 2 Chinese families above and below you? When cooking time comes you can tell which one is chopping just by sitting in your living room.

Re:wow, what insight...

[Anonymous Coward]

That's why dogs and other animals have ears they can move as well as cock their heads. That's what the RCA dog was doing... not looking at the recorr player in amazement, but trying to find a higher pitch noise that was being played

Re:wow, what insight...

[Linknoid]

Yes, the human ear can distinguish vertical position as well. Ever wonder why the outer ear (the pinna) is shaped so weird? It's so it will distort sound coming from different directions differently.

Here's an demonstration I saw at the Exploratorium in San Fransisco, but you can easily reproduce this at home.

Close your eyes, and have someone standing beside you jingle a ring of keys near your ear, above, below, and adjacent. It's easy to tell where the sound is coming from.

Now bend the top cartilage over, so the shape of the ear is distorted, and repeat the previous experiment. Now the easy task of detecting direction becomes almost impossible.

Re:wow, what insight...

[spazdor]

I think he was listening to His Master's Voice.

Re:wow, what insight...

[Lord_Naikon]

It is my understanding that your brain takes both the phase difference and the volume difference between the ears in to account when determining the source of the sound. Up/down/front/back are detected by changes in wave form due to the irregular way the ear is shaped.

Ding-ding-ding

[intellitech]

And the winner is...

Sonar? I think you mean Radar

[AsmCoder8088]

Unless the blind are supposed to be using this device while submerged under water...

Re:Sonar? I think you mean Radar

[AsmCoder8088]

ah, nevermind. SOund NAvigation and Ranging. I shouldn't post past midnight.

Obligatory

[Sulphur]

Another blind side aide: http://www.seeingwithsound.com/

another component

[jlebrech]

this is one component closer to my superhero costume.

Yet more new old technology

[clickclickdrone]

OK, this has some extras but white canes with SONAR and feedback existed in the mid 70's if not earlier.

Re:Yet more new old technology

[Sockatume]

You display an astounding lack of perspective. This is a home-made gizmo that runs off a 9V battery and is only a little bulkier than a fingerless glove with a cellphone stuck to it. I think that's a legitimate advance, in much the same way that the automobile was a significant progression from the steam wagon.

Sonar?

[aglider]

Why a sonar?
Why just "aptic feedback"?
I would have also a few cameras with image recognition (a-la kinect) on a head belt and a synthesized voice to whisper indications to the bearer.
There are materials that cannot be easily detected by sonars as there are objetct not easily recognized by image analysis.
The real breakthrough would be the blind to ask the computer: "what's written on this funny slashdot comment"?
Or, what making noise on my left?

Effective Summarisation

[GodGell]

The Tacit, a wrist mounted sonar device with haptic feedback, is like strapping a bat to your wrist to help you see.

Uh... yeah. That's exactly what it's like.

What about whales?

[Anonymous Coward]

Doesn't the sonar confuse the whales and makes them beach sometimes?

haptic compass

[Ginger Unicorn]

It might be a good combo with this gizmo. Wonder if any blind people have tried the compass out?

Michael McDonald from South Park

[Palmateer]

"I've got an eye on my hand"

they learn eventually

[nten]

My uncle had a small blind dog, and it fairly quickly learned the position of all the furniture in his house and would run around like it was sighted. Course, my uncle wasn't quite right and would move things so he could watch the dog run into them at full speed...

what about the seeing eye dog?

[Anonymous Coward]

Most piezoelectric transducers are 25-40KHz, but cats and dogs can hear up to 60KHz. It will be annoying to them if not painful.

i could have used this back in my teenage years

[Anonymous Coward]

simply asking "why do we have to do this in the dark?" didn't produce the desired results. lengthy searches ensued.