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Three Auditory Illusions

By omnibrain on April 19, 2007.

i-0c9833b5a4ac9e1ac2c96dac036bfcd8-peacock.jpgUsually we feature visual illusions since they seem to be the easiest to make and of course nearly a third to a half of our brain is dedicated to vision so we may just be more interested. In any case here are three auditory illusions from Mighty Optical Illusions.

Shepard's ascending tones (MP3) - This is a recording of Shepard's paradox synthesized by Jean-Claude Risset. Pairs of chords sound as if they are advancing up the scale, but in fact the starting pair of chords is the same as the finishing pair. If you loop this sample seamlessly then it should be impossible to tell where the sample begins and ends.

Falling bells (MP3) - This is a recording of a paradox where bells sound as if they are falling through space. As they fall their pitch seems to be getting lower, but in fact the pitch gets higher. If you loop this sample you will clearly see the pitch jump back down when the sample repeats. This reveals that the start pitch is obviously much lower than the finishing pitch.

Quickening Beat (MP3) - This recording is subtle. A drum beat sounds as if it is quickening in tempo, but the starting tempo is the same as this finishing tempo.

Enjoy!
(via boingboing)

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Woah, the Shepard's paradox one is cool. Does this work just because we pick up on one octave--the note within a particular frequency range--as the prevailing tone? (I'm avoiding the word 'dominant' here.)

By ThePolynomial (not verified) on 19 Apr 2007 #permalink

Might I ask what that picture is of? (The illusions are nifty. The falling bells is strange),

Neat!

One of my favorite composers, Steve Reich, uses effects similar to the last one... especially in his percussion music. Check out "Drumming" for a really fantastic example.

"Might I ask what that picture is of?"
That is some random guy with a bunch of speakers inset in a big piece of plastic... I don't know why he did it though.

By The Omnibrain (not verified) on 20 Apr 2007 #permalink

Ahh, I was hoping for a story :P.

Do you have any research on auditory illusions of the brain in regards to sounds of wind or fans being misinterpreted as voices? If so, could I possible get some info?

Much Thanks, Lisa

By Lisa Emery (not verified) on 09 Oct 2007 #permalink