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Sometimes higher is lower
June 14, 2006 9:30 AM   Subscribe

An audio illusion called the tritone paradox is based on Shepard Tones, a finite self-similar sequence of tones that seem to contiually rise or fall in pitch. Diana Deutch has found that how you percieve these illusions can be strikingly different from person to person and that most people have some form of pefect pitch.
posted by ozomatli (42 comments total) 14 users marked this as a favorite

 
neat
posted by TechnoLustLuddite at 9:45 AM on June 14, 2006


Neat. I saved some of the heavy reading for later, but enjoyed listening to the MP3 found at the 3rd link. I found that if didn't actively listen to pitch, it sounded consistently descending. However, if I listened actively for "what pitch is that?" I could tell when it went high again.

The brain's a funny thing, isn't it?
posted by ivey at 9:46 AM on June 14, 2006


Try humming along. It's pretty disorienting.
posted by Brainy at 9:50 AM on June 14, 2006


Rotate the mouse around the circular "keyboard" and the illusion melts away. I suspect something about the speed and order of the tones changes the brain's interpretation.
posted by Mr. Six at 9:52 AM on June 14, 2006


That is, rotate the mouse quickly...
posted by Mr. Six at 9:52 AM on June 14, 2006


the shockwave sounds in the 4th link are even harder to distinguish.
posted by TechnoLustLuddite at 9:53 AM on June 14, 2006


This is fascinating stuff, thanks.

Here's the sticking point for me: I don't get how they get "ambiguous" tones for the stated experiment(s) unless they're playing multiple tones in different octaves. For instance, if there are two simultaneous C's an octave apart, followed by two F#s, one down a tritone from the lower C and one up a tritone from the upper C, that would be "ambiguous." But that's not described. The details of the research seem to describe using one tone at a time, and yet these are still called "ambiguous" in terms of pitch height. How can that be? I can readily believe that some people might hear them ascending and others descending. But if they're simple tones rather than groups of tones, the two notes are in fact either ascending or descending. One group of hearers is wrong, the other right. The wording "there is literally no right or wrong answer" is, um, the wrong answer.

Can anyone clarify this for me? What am I missing?
posted by soyjoy at 10:05 AM on June 14, 2006


Level 1.2, Super Mario Bros anyone?
posted by jon_kill at 10:06 AM on June 14, 2006


This is amazing. I've seen a million optical illusions in my time, but this is the first audio illusion I've encountered. I feel like it broke my brain.
posted by Faint of Butt at 10:07 AM on June 14, 2006


(Slip into water over his head)

Dude, this so reminds me of Mario Brothers.
posted by 517 at 10:10 AM on June 14, 2006


...and jinx.
posted by 517 at 10:10 AM on June 14, 2006


There used to be a demo app for the Mac years ago that featured a ball moving along an Escher staircase to Shepherd tones.
posted by plinth at 10:22 AM on June 14, 2006


I first heard Shepard tones in the intro to Macrometasomakosmos by Ubar Tmar (extended version of intro here). If you think it sounds weird when you listen to it knowing it's an audio illusion, imagine listening to it go on for 5 or so minutes without knowing it's an audio illusion. I believe my impression was somewhere along the lines of "What the hell?! This can't keep going up any higher, I'm going to blow out the speakers or wake up all the dogs in a 10 mile radius. And, wait, why the hell can I still hear it, anyway?"
posted by Bugbread at 10:26 AM on June 14, 2006


On the Deutsch page she has this mystery melody, has anyone figured out what it is? I have no clue, but I guess if someone tells me then I will be able to hear it.
posted by ozomatli at 10:27 AM on June 14, 2006


This is good.
posted by Opposite George at 10:33 AM on June 14, 2006


This is enormously good.
posted by boo_radley at 10:37 AM on June 14, 2006


Ozomatli,

The mystery melody's fun (remember a similar exercise at college when someone played Happy Birthday with all the octaves randomised).

This one's harder though, as (nearly) all the notes are the same length, so there aren't any rhythmic clues. The last two notes, in fact, are how I got it: popular tune that ends it's first phrase on two long notes; tonic then leading note?

*SPOILER*




Why yes, it's Yankee Doodle!
posted by dogsbody at 10:40 AM on June 14, 2006


I've owned her CD for several years, and it's quite interesting to break out at a party.
posted by nomisxid at 10:43 AM on June 14, 2006


Can anyone clarify this for me? What am I missing?

No, I think you're right, at least if the explanation on this page applies.
posted by cillit bang at 10:47 AM on June 14, 2006


Funny, depending on which "part" of the second sound I concentrate on (at the tritone paradox) I can "choose" to hear either a descending or an ascending tone. Anyone else?
posted by vertriebskonzept at 10:49 AM on June 14, 2006


soyjoy, I'm not getting that from the link. They seem to be using the word "tone" to apply to a waveform consisting of many octaves of a particular note: "The tones that are used to create the tritone paradox are so constructed that their note names (C, C#, D and so on) are clearly defined, but they are ambiguous with respect to which octave they are in. For example, one tone might clearly be a C, but in principle it could be middle C, or the C an octave above, or the C an octave below. This ambiguity is built into the tones themselves."

vertriebskonzept, I too found I could force myself to hear them either way.

This is neat stuff. Thanks ozomatli!
posted by solotoro at 11:28 AM on June 14, 2006


I could swear that this has been used in a television show... maybe a Dr. Who episode?
posted by weston at 11:31 AM on June 14, 2006


The Pink Floyd song Echoes fades out with this effect. I often wondered how they did that; now I see there's a Wikipedia page answering that and many other late night bong hit questions.
posted by bjrubble at 11:39 AM on June 14, 2006


The Queen album "A Day At The Races" starts and ends with something quite like a Shepard Tone. Brian May states that he came up with it independently while trying to emulate the endless staircases of an M.C. Escher painting.

Brian May's explanation (search for Shepard)
posted by dr. fresh at 11:41 AM on June 14, 2006


Warning: the continuous rising tone on headphones hurt my ears.
posted by sonofsamiam at 12:10 PM on June 14, 2006


This is cool, thanks.
posted by interrobang at 12:34 PM on June 14, 2006


The Doppler Effect is an auditory illusion of sorts and we hear it every time a car or siren passes by.

And this Tritone thing is neat, though I'm tired and can't really understand it fully at the moment.
posted by SmileyChewtrain at 1:00 PM on June 14, 2006


solotoro, you must be right, though it mystifies me why they would a) use the word "tone" which has a specific meaning that does not include multiple tones, and then b) never use the phrase "multiple tones" or "multiple octaves" to clarify how the tone itself could contain built-in "ambiguity." But not all the most interesting research is done by the people who write it up most clearly. Still a fascinating phenomenon.
posted by soyjoy at 1:24 PM on June 14, 2006


The Doppler Effect is an auditory illusion of sorts and we hear it every time a car or siren passes by.

That's not really an illusion that's what the sound actually sounds like when it gets to your years, whereas optical illusions are caused your visual processing systems.

Anyway, I feel like you really need to know a lot about music theory to appreciate (or even notice) these.
posted by delmoi at 3:12 PM on June 14, 2006


It's interesting to play the samples before reading the text, to see if the effect works on you. In any event, the 'Cambiata' illusion didn't work on me.
posted by delmoi at 3:17 PM on June 14, 2006


Okay, okay, I've been caught - I knew that about The Doppler Effect before posting but I wanted to test to see if the MetaFilter crowd was smart enough to catch me!

Ha-HA! You *are* smart enough! Or at least, delmoi is. delmoi, you get a cracker. I'll sit down now.

It's still a neat effect, however, that continues to mystify me even though I understand why it happens.
posted by SmileyChewtrain at 3:40 PM on June 14, 2006


Pardon my French, but what a fucking synchronicity. Just yesterday I stumbled across Deutsch's Phantom Words and Other Curiosities as I was cleaning out my CD shelf!
posted by digaman at 4:02 PM on June 14, 2006


I've been watching you digaman.......
posted by ozomatli at 4:23 PM on June 14, 2006


If SmileyChewtrain finds the Doppler Effect mystifying, he should try getting his head round the relativistic Transverse Doppler Effect (wikilink).
posted by edd at 4:43 PM on June 14, 2006


The MP3 of tritone paradox versions on the Deutsch site contains four examples. The last one is ambiguous and can be heard both as rising and as falling. This suggests a species of quantum indeterminacy, where the listener's election to hear one direction of tritonal interval change determines the phenomenon.
posted by rdone at 6:16 PM on June 14, 2006


This suggests a species of quantum indeterminacy, where the listener's election to hear one direction of tritonal interval change determines the phenomenon.

Or it just goes down:

posted by cillit bang at 8:45 PM on June 14, 2006


Shepard tones:

posted by cillit bang at 9:13 PM on June 14, 2006


cillit bang, what software is that?
posted by Bugbread at 10:02 PM on June 14, 2006


Ah, sweet, I've been thinking about plotting a frequency map of that MP3 all day....it's looks pretty much like I imagined it...

The odd thing is, the Shepard tone illlusion is, at least for me, very easy to re-create in your head...just think of an ever increasing, or decreasing tone, and you get much the same effect.

It raises an odd question, though - I'm nearly 30 now, and I've definitely lost the 20Khz+ hearing I used to have....but listening to19Khz sounds now, I'm completely unable to imagine the sounds I'm now missing - why should this be, given that I've got experince of what they sound like?
posted by Jon Mitchell at 2:09 AM on June 15, 2006


It's a free Java app called Sonogram Visible Speech.

(If it complains that it needs Java 1.5, you actually need to install Java 2 SE 5.0)
posted by cillit bang at 3:00 AM on June 15, 2006


The radio show Radiolab has a great program about this, and other, sound candy.

link
posted by sunexplodes at 8:27 AM on June 15, 2006


I love the misspelling of 'perfect' ozomatli.

*shows finger to pedants*
posted by Shave at 4:58 AM on June 16, 2006


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