Amazing auditory illusion


Here is a terrific auditory illusion called a Shepard scale. Listen to the video, then replay it. Again. And again. And again. From Wikipedia: A Shepard tone, named after Roger Shepard, is a sound consisting of a superposition of sine waves separated by octaves. When played with the base pitch of the tone moving upwards or downwards, it is referred to as the Shepard scale. This creates the auditory illusion of a tone that continually ascends or descends in pitch, yet which ultimately seems to get no higher or lower. Shepard tone illusion (YouTube, via Mind Hacks)

Previously on BB:
Fun auditory illusions

44

  1. I wasn’t expecting to be that impressed until I rewound it and my mouth fell open. That is so cool and weird and I’m almost mad at my brain for not being able to…not be illusion-ed by it.

  2. That has to be one of the worst demonstrations of the Shepard tone I’ve heard; the fact that you have to intervene kind of destroys the illusion.

    My own subjective perception of the discrete Shepard scale, which some others have shared, is there is a point in the scale at which the dominant tone seems to drop an octave. The continuous glissando, of which there’s a sample on the linked Wikipedia entry, is much more effective.

  3. It doesnt destroy the illusion at all for me, it works exactly as they say it will, even with having to restart it.

  4. Basically, forcing the audience to replay the video to experience the illusion reveals how it works. What happens is that the lower octave ends at the same place that the upper octave starts, so a couple of iterations look like the following (time progressing left to right, | between iterations):

    -| –
    – | –
    – | –
    – | –
    – | –
    – | –
    – |-
    – +
    -| –
    – | –
    – | –
    – | –
    – | –
    – | –
    – | –
    – +

  5. I guess the fact that you re-wind it forces you to acknowledge that you’re listening to the same notes, but I think it would be much better if it had gone around a few more times.

    I don’t get the Wikipedia version at all. It seems to waver all over the place.

  6. from the way I hear it upon replay, only the first two sets of tones pitch up, and then the lower octave takes precedence and pulls the tones back to the original mark.

    But that’s a pretty cool auditory illusion.

  7. Well, lack of spacing ruined that one well. Let’s try again:

                                -|                        –
                            -    |                    –
                        -        |                –
                    -            |            –
                -                |        –
            -                    |    –
        -                        |-
    -                            +
                                -|                        –
                            -    |                    –
                        -        |                –
                    -            |            –
                -                |        –
            -                    |    –
        -                        |-
    -                            +

  8. It’s pretty cool for the average Joe. For those of us who were music majors and trained to write out bass lines by ear, our brains are only fooled for a second or so before they adjust to the lower octave. :)

  9. At #8: I felt something like that too. I played it about 4 times and felt tension starting to build up in me. Like I was waiting for something to happen but it never did. I wonder how something like that would play in a film? Like a very subtle barely audible progression through a tense quiet scene.

  10. I undoubtedly still have a 3″ reel of tape that includes some of this from about 1971, when I heard them do this on KMYR and ran for my little recorder. After that, I played around with it — backwards, faster speed, really really fast speed, and so on. At reverse high speed, it was pretty clear that they were mixing octaves in and out.

    It’s still pretty neat, though. My hat’s off to whoever thought of it first. (It seems like somebody has been noticing this every couple of weeks or months lately. I’m getting really good at writing this comment.)

  11. I believe the Beatles were the first to use this in a popular music form at the trail out of I Am The Walrus. Another example would be Elvis Costello’s Just Like Candy, again at the end. The aural eqivalent of Escher’s Ascending and Descending.

  12. I heard this for the first time at an IEEE section meeting in the spring of 1966. It was used as an accompaniment to a demonstration of an early computer graphics animation done at Bell Labs. A ball was bouncing up the infinite staircase in an Escher drawing as the tone got higher and higher. Cool, really cool. But even cooler… At some point the ball reversed, bounced down the staircase, as the tone got lower and lower. I was so impressed that I remember it to this day, 42 years later. I believe that some of the people involved in the demo worked with Max Mathews a pioneer in electronic music.

  13. This is an oldy, but a goody.

    Personally, I like the continuous ‘Risset’-style better, as nprnncbl mentioned, although not necessarily the one on wikipedia. And while I agree that this demonstration model has the benefit of making you interact, therefore confronting the effect head-on, the other style (continuous) is an entirely different matter.

    Trust me, if you listen to a constantly rising tone for, say, 15 minutes, and it doesn’t reach any kind of conclusion or rise out of range, your brain starts melting (whether or not it took drugs to make you listen to the Shepard for that length of time :) ).
    On a related note, the decending Risset tone, is actually quite an emotional downer. It really is depressing. The flip side of that is, of course, that the ascending version is quite stimulating (in a manic kind of way).
    It is quite a bizarre sensation either way, you should definitely try the upwards-continuous one for a decent interval, just to approach aural-madness.. It is quite a beautiful thing, as things go.

    There is a freeware VST from MDA that creates Risset-style Shepard tones. You can change the rise-time and the direction, it’s simple but perfectly effective.

    If you listen long enough, your ears turn inside-out. And then drop off.

    Fact.

  14. I also have the proud distinction (whether you grant it to me or not) of seperately inventing this effect (quite a long time after Shepard, obviously).

    I had never heard of it, or been aware of it’s existence, but surmised the possibility of multiple layered-sweeps, sneaking in below our hearing range and then sneaking back out again above. I achieved it using SoundEdit16, some years before discovering the MDA plug-in mentioned above, or coming across the actual theory put forth by Shepard.

    Ah well, it wasn’t worth a million pounds, so I’ll let Shepard keep it.

  15. For those of us who were utterly spangled during the 80s & 90s, hugging a speaker cabinet in a field somewhere near the M25, it comes as no surprise. Still cool though.

  16. I was thinking about this auditory illusion during The Dark Knight, because the Joker’s theme sort of reminded me of it. Constantly building tension that doesn’t seem to break.

  17. Neatoh. Anyone have long recordings of the phenomenon Arkizzle was talking about? (I tried yours, Ark, but I’m not on Mac.)

  18. weird, it only goes up twice for me. when I click it a third time I hear it back at the “beginning”. good times.

  19. Hands down, my favorite auditory illusion. I’ve spent plenty of time coaxing different synthesizers/software to reproduce such an effect.

    Though the concept is fairly simple, getting it to sound just right can sometimes prove pretty challenging.

  20. AtP

    I was going to tell you how repellent that will make your page.. but Then I remembered you said Myspace :)

    Also, I notice the filehost I used is describing it as a ringtone.. Now that would be annoying.

  21. Anyone remember Super Mario 64? There was a staircase that looped infinitely until you got a certain number of stars, and the accompanying music was a variation on the Shepard scale.

  22. @Codeman38…I was just about to say that! Most people should be more familiar with that example.

    I love this trick. It’s also possible to boost the upper frequencies of a tone to give the illusion of more bass, because that’s just how the brain works.

  23. @ #24. Now I have 4 audio files that will never end. Thanks in advance for the padded room this will put me in. 2 minutes and I can’t take it anymore.

    @ #8. Me Too.

  24. I have to say, Arkizzle’s ascending files made it easier to hear the effect, while the YouTube link above masks it.

    The ascending files also… reminded me of a race car.

  25. I don’t know if anyone else had this experience, but within seconds of starting the first round, my dog came racing in my office whimpering for me to stop.

    Anyone know anything about what this see-saw of octaves does to a dog’s ear?

  26. If you have a Microkorg keyboard, it has a patch based around the Shepard scale, so you can play through an octave on the keys and try to tie the position of your finger with the pitch. It’s hidden under the waveform oscillator options.

  27. OK, The science behind the phenomenon may be accurate, but this video/audio is bogus. I don’t know how it’s done, but if you play about halfway thru the loop, then pull the bar back and play again, there is an “OBVIOUS” decline in the tone. That tells me it’s a programming loop of some sort and not the actual phenomenon. I say Boo! on this particular video.

    It was a nice try though…

  28. Johnny5, of course the effect doesn’t work if you stop it halfway through, the effect is produced by raising several layered frequencies (seperated by one octave) up by one octave, repeatedly.

    The start frequency of each layer is the end frequency of each subsequent layer. If you stop the rise halfway through, the effect hasn’t had time to work.

    ..it’s a programming loop of some sort and not the actual phenomenon.

    I’m not sure what the distinction is.

  29. I was pleasantly surprised to discover I can clearly hear the sweeping high-to-low transitions in the continuous tone (thanks for posting those, Arkizzle).

    I guess after a few years of radio production, listening closely to strange waveforms in various combinations (often hundreds of times over the course of cutting something together), my ears have been taught to notice this stuff.

    Very cool.

  30. For you electronic music fans, YMO (Yellow Magic Orchestra) did a track called ‘Loom’ on their album BGM that uses the shephard scale.

  31. Heh, and for those of us who are completely tone deaf, it all sounds exactly the same. It just sounded like the same thing repeated over and over, even within a single run.

  32. …Two points:

    1) “I don’t get the Wikipedia version at all. It seems to waver all over the place.”

    …That, my friend, is typical Wikipedia for you. What do you expect when they let prepubescent British schoolboys be admins? The inmates run the asylum over there, and every article should be taken with at least three grains of salt. Hell, on OMBlog I only add a “Wikilink of the Day” just for gits and shiggles.

    2) Has anyone tried jumping from one end of the clip to the other, then rewinding it? About half the time the effect will be heard, and the other half it won’t.

  33. My years as a teenage fanboy of Queen and Pink Floyd compel me to add that both the beginning of Queen’s album “A Day At the Races” and the end of Pink Floyd’s 1971 album “Meddle” feature also a Shepard scale, in an arguably more musical way than this example. It’s not *that* uncommon!

Comments are closed.