Amazing Audio Illusion!

re: Amazing Audio Illusion!

jimbobg — Tue, 06 Nov 2007 00:47:30 GMT

This is an easy one to understand, but quite difficult for me to explain. Basically, it's using octaves (doubles) of sine waves (pure tones) to create a full sound. When the sound gets to the next octave, it will be double what it was, but your ears can't distinguish that because they only have a range between 20Hz and 20,000Hz.

Example:

Starting sound contains pure tones of:

55Hz, 110Hz, 220Hz, 440Hz, 880Hz, 1760Hz, 3520Hz, 7040Hz, 14080Hz

Once it has gone through all musical notes and come to its next octave, it will contain:

110Hz, 220Hz, 440Hz, 880Hz, 1760Hz, 3520Hz, 7040Hz, 14080Hz, 28160Hz

Your ears will hear this as being the same as the original, even though it's twice the frequency. The only difference is the addition of the 28160Hz tone and the lack of the 55Hz tone. Your ears can't hear the 28160Hz tone, and can't really tell that the 55Hz tone has disappeared, so it assumes that the sound is exactly the same, because all the other frequencies are still resident in the sound.

I hope as a sound engineer and not a teacher, that I've been able to explain this clearly so everyone can understand ;)

re: Amazing Audio Illusion!

Mad_203 — Mon, 05 Nov 2007 04:47:25 GMT

Is this another left/right brain conundrum? I get both effects simultaneously, but I can't quite explain how. It's the audio equivalent of the M.C. Escher print of the impossible staircase, where it seems as if people ascend forever, but they are climbing the same series of steps over and over.

I think I would make a really lousy trial witness.

re: Amazing Audio Illusion!

illusions — Sun, 04 Nov 2007 19:46:58 GMT

When repeated, forms a variation of Bach‘s ‘Endless Rising Canon‘, a technique common in popular music! Enjoy in good health!

re: Amazing Audio Illusion!

david — Sat, 03 Nov 2007 10:22:41 GMT

I see a lot of comments on You Tube. such as "wow, Thats cool", etc. etc.

...Are these the same people/kids who are consuming vast quantites of junk food, cocacola, et al do you think?!!

...... Same kind of susceptability to illusion perhaps :)

re: Amazing Audio Illusion!

david — Sat, 03 Nov 2007 10:13:51 GMT

...Nice piece of humour Islander! :0)

re: Amazing Audio Illusion!

TomRobinson — Sat, 03 Nov 2007 07:17:50 GMT

The audio is not an ascending chromatic scale, even though that's what it sounds like. Each note is a specific combination of several frequencies, and the first note and the last note are exactly the same.

re: Amazing Audio Illusion!

Bob2_203 — Wed, 17 Oct 2007 14:33:34 GMT

Well, I guess it's supposed to create an illusion of higher pitches on the next listen, even though it's always the same audio.

Being a musician, this has zero personal effect, as this is simply an ascending chromatic pattern from B to B, which sounds exactly the same on each replay. Maybe one needs to be left-eared? :)

re: Amazing Audio Illusion!

Russ Bianchi — Tue, 16 Oct 2007 19:49:35 GMT

Dopler Effect?

re: Amazing Audio Illusion!

samurai — Tue, 16 Oct 2007 13:56:40 GMT

I don't get it. Maybe someone can help me out here? (too many Pepsi Colas in my past life or something....)