A guest post by Dante.
Wonderful Freeman invited me to write up a math/computer science post, and so here it is. Math seems like common sense, and if you only think of it you can understand it. So here is a little puzzle you can think about to explain a common phenomenon: why is it that if you are in a shower, or on a treadmill, it's really hard to hear someone call out to you, even though they can hear you.
I have three (impulsive) boys, and as such I encountered this often. The answer is pretty simple, and with a couple of concepts, you can puzzle it out for yourself.
The first concept is Signal to Noise Ratio (SNR). Here, voice is the signal, and noise is anything generating sound that isn't part of the signal (like the shower or treadmill). In general, to decipher a signal, it has to be stronger than the noise. How much stronger isn't too important for the concept part of it.
The next concept is that over distance, sound (noise or signal) decreases in strength.
With these two concepts, you can use common sense to figure out what is going on.
Here's a graphic of it:
The person on the left can hear because both the noise source and the voice signal drop in strength, but the Signal to Noise Ratio stays the same (sound uses decibels, which is a logarithmic scale, not important for the concept) . They can hear. On the other hand, the person on the right has a very loud noise source to compete with a signal that has become weak. In this case, the signal has dropped below the noise, and so it becomes inaudible.
This is an example in which I think merely thinking of the problem with a couple of concepts can let you figure out what's going on. If you understand the above (not to be insensitive to those who don't, it's probably my presentation), or those who think this is so patently obvious (it can definitely be that too), but the point is that with concepts and common sense math is accessible.
This particular idea came from a startup I was working with, that had a lot of “Digital Signal Processing” experts. As I tried to get a working model in my mind to be able to make some sense of what the tiny company was trying to do, I explored some of it, though not in the rigor of my college days (on my list of things to do before I die).
This also had a practical application in a problem I was trying to solve later. There was some strange behavior in a wireless network (radios). It turned out it was the shower problem, but with Wireless Access Points (wifi, what many use in their homes). It turns out there was a noise source (interferer) from the San Jose Airport. Same problem. The Aps near the airport could not hear Aps farther away, but vice versa worked. The RF engineer got stumped by it.
It also solved the problem in my own family of people thinking they were intentionally being ignored. Once they understood this, they realized it wasn't something intentional, and the conflicts went away.
Meanwhile, this is a very basic concept useful to a booming discipline, Information Theory, that has broad application across a wide range of fields. Dr. Claude E. Shanon developed information Theory. The people I know who are more intimate with this consider Shanon a modern day Einstein.
45 comments:
The dog can smell you in the shower but you can't smell the dog.
The shower door effect, where you can see the person in the shower but they can't see you.
In short showers cut you off from the world in every sense except hunger.
Re: "The shower door effect"
I Can't Help But Think of Kentucky Fried Movie's "Catholic High School Girls in Trouble."
Now THAT was a Shower Door.
The world can see you though. That's the show in shower.
You don't see the meteors in meteor showers. You see the shower doors.
Blame makes its way inward through shower doors.
It's like electric theory, having chosen the wrong sign on the charge so everything goes backwards.
Avoid antimatter showers, door or not, even though there blame works out correctly.
Fish gotta swim, birds gotta fly, showers gotta elucidate.
Anybody besides me ever go to the library, and you pick up your materials, and you're walking back to your car, and it suddenly dawns on you that you were flirting with the librarian behind the counter, and she was flirting back, and she's really, really cute, and nothing will ever come of it because you're married and, hell, you might be old enough to be her father, anyway?
No?
Didn't think so.
But it just happened to me not a half-hour ago and, boy, am I all discombobulated.
How the hell is it even possible to flirt without knowing it?
I must be nuts.
Show me your nuts!
(betamax3000 gets it.)
Blame works like the greek theory of sight.
You see stuff because seeing eminates from your eye and hits the apple seen.
That explains why if you put your hand in the way, you see your hand instead, if anybody ever asks.
It has trouble with the modern turning the lights on effect, but modern has perverted everything.
Re: "modern has perverted everything"
Post-Modern Has Deconstructed the Perversion and Reassembled it as Society.
Kings do not touch shower doors.
@rh: Your shower analogy is golden!
Blame is a particle, not a wave.
Otherwise piling on could not be explained.
Blame piles in a stable cone owing to a critical instability. Avalanches at the critical point keep the shape constant.
There are also blame hour glasses, used to measure time.
This survives as a time out.
Nobody knows what governs the operation of an hour glass.
It seems to be a process of structural lockup and release.
Blame is probably similar.
Clocks were invented because physicists could not explain hour glasses.
Blame solved the longitude problem.
Everybody blamed the navigator.
When water is scarce you take a dry shower.
Clocks were invented because physicists could not explain hour glasses.
"Days Of Our Lives" appealed to females. You know your audience, rh.
rhhardin said...
Blame is a particle, not a wave.
Otherwise piling on could not be explained.
But that doesn't explain frequency, amplitude, and interference (constructive and destructive).
Physicists welcomed women by renaming top and bottom quarks truth and beauty quarks.
This just replaced something easy to remember with something hard to remember.
I have an atomic clock on the wall right now that's precisely four hours slow, to the millisecond.
Digital timekeeping makes that mistake possible.
I think a shower is one of the greatest simple pleasures there is. It can make everything seem a little better.
Not when I take one, but when you do.
Physicists were afraid women would see it as a hostile workplace.
Keats and the urn had nothing to do with it.
Pipes and tumbrels.
Cosmologists have a hostile workplace no matter what they do.
We are fucked.
rh
lol
Women cosmologists do not seem happy.
It might have been a misunderstanding about the name.
In Spanish a sponge bath is called - baño de Ave Maria.
db is usually written dB in engineering to prevent doodling.
Althouse had a post about regularly changing the shower head.
its a bacteria hang out or something.
My sister had an odd way with her boys when they were small.
She yelled at them and they ignored her. In their world she was part of the noise. So she yelled more and they ignored more. Until she blew up and doubled the volume and they responded appropriately like the good boys they are.
She had to reach a level of intensity or they flat did not respond.
As observer, I wonder, why not skip the first four regular yells and get directly to the double volume yell? And having achieved that, why not a soft instruction instead with the force of a double-volume yell? So much better all aro...
pardon me I must put the president on mute -- annoying cadence annoys --
...better all around.
She was the opposite of the dog trainers at the dog training club, all of them knew better than that.
It works on the premise that the dog's hearing is acute and they are paying attention.
They have to learn to pick out your instructions, and that comes from consistency. Complete reliable consistency all around and that is where people fail.
My sister consistently gave three or four of the same suggestion before imposing it as demand.
Goes like this, "Kids, hold it down in there, we're trying to talk and you are being too noisy."
Next noise, bang, drag the kid out of the room without another cross word or angry fuss. "You'll have to stay in this room by yourself on account of the noise you keep making, until the big hand goes around five times and the little hand goes from there to there. Then you can come back out and join the others."
And the dog owners who show in obedience as a generality do have the most well-behaved children. Not because they treat them like dogs, but because they learned to be reliably consistent with them.
Lem, in cooking, a water-bath is bain-marie, for baking to keep the heat even and low surrounding something in a separate pan placed into the bath, as cheesecake and such.
You can keep a dog from shaking dry after a shower by giving it a dumbbell to hold, and saying "Hold."
You will have taught the hold as part of the fetch, and it means hold this until I take it from you.
The shake-dry starts at the head and works to the tail.
With a dumbbell, the shake can't start.
Take the dog outside, and say give. Then the dog shakes dry.
I noticed the hourglass tattoo on the arm of the bird who exposed the Anthony Weiner debacle is half done. That seems a statement about time passing, and the sand in the tattoo is half passed. Maybe she sleeps with her arm up in the hope of extending her life.
I also found that if you want the dog to shake but they just stand there staring at you, you can shake yourself and that usually does it, but personally I start my shake at the tail. It makes me feel a little randy. I have a number of psycho-behavioral alternatives to testosterone replacement and this is one.
This post came in handy today when I was outside using a loud electric air pump.
I bake my cheesecakes in a water bath or at very low temps. Works beautifully.
Dante, it's intriguing how you linked the concept to interpersonal behavior. I'm going to ponder that. Great post.
Blogger Mitchell the Bat said...
Anybody besides me ever go to the library, and you pick up your materials, and you're walking back to your car, and it suddenly dawns on you that you were flirting with the librarian behind the counter, and she was flirting back, and she's really, really cute, and nothing will ever come of it because you're married and, hell, you might be old enough to be her father, anyway?
No?
Didn't think so.
But it just happened to me not a half-hour ago and, boy, am I all discombobulated.
How the hell is it even possible to flirt without knowing it?
I must be nuts.
July 27, 2013 at 11:50 AM
Who says the library is boring?
Reading is fundamental!
Mitchell the Bat, this one is for you...
I wonder if another factor is the ear's non-linear response to frequency. Depending on the sex of the person nagging you when working out or taking a shower, the fundamental frequency of the voice will range from 85 Hz to 250 Hz. In telephony, the voice frequency band ranges from 300 Hz to over 3000 Hz. The non-linear response characteristics of the human ear permit us to hear harmonics and imply the underlying fundamental tones, even if we don't really hear them.
The sound characteristics of water are surprisingly complex, but I image it's in the 5000 Hz range.
Machinery sounds can easily exceed 25 kHz.
Since the ear responds to the higher frequencies better than the lower frequencies (probably on the same logarithmic scale), it is not surprising that we can more easily ignore the nagging human voice, the owner of which doesn't understand the concept of leave-me-alone-can't- you-see-I'm- busy.
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